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1.
BMC Cancer ; 17(1): 836, 2017 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-29221446

RESUMO

BACKGROUND: A systematic review was conducted to assess the diagnostic test accuracy of polymerase chain reaction (PCR)-based microsatellite instability (MSI) testing for identifying Lynch syndrome in patients with colorectal cancer (CRC). Unlike previous reviews, this was based on assessing MSI testing against best practice for the reference standard, and included CRC populations that were unselected, age-limited or high-risk for Lynch syndrome. METHODS: Single- and two-gate diagnostic test accuracy studies, or similar, were identified, assessed for inclusion, data extracted and quality appraised by two reviewers according to a pre-specified protocol. Sensitivity of MSI testing was estimated for all included studies. Specificity, likelihood ratios and predictive values were estimated for studies that were not based on high-risk samples. Narrative synthesis was conducted. RESULTS: Nine study samples were included. When MSI-Low results were considered to be negative, sensitivity estimates ranged from 67% (95% CI 47, 83) to 100% (95% CI 94, 100). Three studies contributed to estimates of both sensitivity and specificity, with specificity ranging from 61% (95% CI 57, 65), to 93% (95% CI 89, 95). Good sensitivity was achieved at the expense of specificity. When MSI-L was considered to be positive (effectively lowering the threshold for a positive index test result) sensitivity increased and specificity decreased. Between-study heterogeneity in both the MSI and reference standard testing, combined with the low number of studies contributing to both sensitivity and specificity estimates, precluded pooling by meta-analysis. CONCLUSIONS: MSI testing is an effective screening test for Lynch syndrome. However, there is significant uncertainty surrounding what balance of sensitivity and specificity will be achieved in clinical practice and how this relates to specific characteristics of the test (such as the panel of markers used or the thresholds used to denote a positive test).


Assuntos
Neoplasias Colorretais Hereditárias sem Polipose/diagnóstico , Neoplasias Colorretais Hereditárias sem Polipose/genética , Instabilidade de Microssatélites , Técnicas de Diagnóstico Molecular/métodos , Técnicas de Diagnóstico Molecular/normas , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Adulto Jovem
2.
Nephrol Dial Transplant ; 32(7): 1251-1259, 2017 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-28873970

RESUMO

BACKGROUND: Immunosuppression is required in kidney transplantation to prevent rejection and prolong graft survival. We conducted an economic evaluation to support England's National Institute for Health and Care Excellence in developing updated guidance on the use of immunosuppression, incorporating new immunosuppressive agents, and addressing changes in pricing and the evidence base. METHODS: A discrete-time state transition model was developed to simulate adult kidney transplant patients over their lifetime. A total of 16 different regimens were modelled to assess the cost-effectiveness of basiliximab and rabbit anti-thymocyte globulin (rabbit ATG) as induction agents (with no antibody induction as a comparator) and immediate-release tacrolimus, prolonged-release tacrolimus, mycophenolate mofetil, mycophenolate sodium, sirolimus, everolimus and belatacept as maintenance agents (with ciclosporin and azathioprine as comparators). Graft survival was extrapolated from acute rejection rates, graft function and post-transplant diabetes rates, all estimated at 12 months post-transplantation. National Health Service (NHS) and personal social services costs were included. Cost-effectiveness thresholds of £20 000 and £30 000 per quality-adjusted life year were used. RESULTS: Basiliximab was predicted to be more effective and less costly than rabbit ATG and induction without antibodies. Immediate-release tacrolimus and mycophenolate mofetil were cost-effective as maintenance therapies. Other therapies were either more expensive and less effective or would only be cost-effective if a threshold in excess of £100 000 per quality-adjusted life year were used. CONCLUSIONS: A regimen comprising induction with basiliximab, followed by maintenance therapy with immediate-release tacrolimus and mycophenolate mofetil, is likely to be effective for uncomplicated adult kidney transplant patients and a cost-effective use of NHS resources.


Assuntos
Rejeição de Enxerto/economia , Terapia de Imunossupressão/economia , Imunossupressores/economia , Transplante de Rim/economia , Modelos Econômicos , Adulto , Análise Custo-Benefício , Inglaterra , Rejeição de Enxerto/tratamento farmacológico , Rejeição de Enxerto/etiologia , Sobrevivência de Enxerto , Humanos , Imunossupressores/uso terapêutico , Transplante de Rim/efeitos adversos , Masculino , Pessoa de Meia-Idade , Programas Nacionais de Saúde , Anos de Vida Ajustados por Qualidade de Vida
3.
BMC Cancer ; 15: 313, 2015 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-25910169

RESUMO

BACKGROUND: Lynch syndrome is an autosomal dominant cancer predisposition syndrome caused by mutations in the DNA mismatch repair genes MLH1, MSH2, MSH6 and PMS2. Individuals with Lynch syndrome have an increased risk of colorectal cancer, endometrial cancer, ovarian and other cancers. Lynch syndrome remains underdiagnosed in the UK. Reflex testing for Lynch syndrome in early-onset colorectal cancer patients is proposed as a method to identify more families affected by Lynch syndrome and offer surveillance to reduce cancer risks, although cost-effectiveness is viewed as a barrier to implementation. The objective of this project was to estimate the cost-utility of strategies to identify Lynch syndrome in individuals with early-onset colorectal cancer in the NHS. METHODS: A decision analytic model was developed which simulated diagnostic and long-term outcomes over a lifetime horizon for colorectal cancer patients with and without Lynch syndrome and for relatives of those patients. Nine diagnostic strategies were modelled which included microsatellite instability (MSI) testing, immunohistochemistry (IHC), BRAF mutation testing (methylation testing in a scenario analysis), diagnostic mutation testing and Amsterdam II criteria. Biennial colonoscopic surveillance was included for individuals diagnosed with Lynch syndrome and accepting surveillance. Prophylactic hysterectomy with bilateral salpingo-oophorectomy (H-BSO) was similarly included for women diagnosed with Lynch syndrome. Costs from NHS and Personal Social Services perspective and quality-adjusted life years (QALYs) were estimated and discounted at 3.5% per annum. RESULTS: All strategies included for the identification of Lynch syndrome were cost-effective versus no testing. The strategy with the greatest net health benefit was MSI followed by BRAF followed by diagnostic genetic testing, costing £5,491 per QALY gained over no testing. The effect of prophylactic H-BSO on health-related quality of life (HRQoL) is uncertain and could outweigh the health benefits of testing, resulting in overall QALY loss. CONCLUSIONS: Reflex testing for Lynch syndrome in early-onset colorectal cancer patients is predicted to be a cost-effective use of limited financial resources in England and Wales. Research is recommended into the cost-effectiveness of reflex testing for Lynch syndrome in other associated cancers and into the impact of prophylactic H-BSO on HRQoL.


Assuntos
Neoplasias Colorretais Hereditárias sem Polipose/diagnóstico , Idade de Início , Idoso , Neoplasias Colorretais Hereditárias sem Polipose/economia , Neoplasias Colorretais Hereditárias sem Polipose/genética , Análise Custo-Benefício , Análise Mutacional de DNA , Tomada de Decisões Assistida por Computador , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Econômicos , Técnicas de Diagnóstico Molecular/economia , Anos de Vida Ajustados por Qualidade de Vida , Risco , Sensibilidade e Especificidade
4.
Value Health ; 16(2): 288-96, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23538180

RESUMO

OBJECTIVES: To estimate the cost-effectiveness of cetuximab monotherapy, cetuximab plus irinotecan, and panitumumab monotherapy compared with best supportive care (BSC) for the third and subsequent lines of treatment of patients with Kirsten rat sarcoma wild-type metastatic colorectal cancer from the perspective of the UK National Health Service. METHODS: An "an area under the curve" cost-effectiveness model was developed. The clinical effectiveness evidence for both cetuximab and panitumumab was taken from a single randomized controlled trial (RCT) in each case and for cetuximab plus irinotecan from several sources. RESULTS: Patients are predicted to survive for approximately 6 months on BSC, 8.5 months on panitumumab, 10 months on cetuximab, and 16.5 months on cetuximab plus irinotecan. Panitumumab is dominated, and cetuximab is extended dominated. An incremental cost-effectiveness ratio (ICER) of £95,000 per quality-adjusted life-year (QALY) was estimated for cetuximab versus BSC and is likely to be relatively accurate, because the relevant clinical evidence is taken from a high-quality RCT. The estimated ICER for panitumumab versus BSC, at £187,000 per QALY, is less certain due to assumptions in the adjustment for the substantial crossing-over of patients in the RCT. The ICER for cetuximab plus irinotecan versus BSC, at £88,000 per QALY, is least certain due to substantial uncertainty about progression-free survival, treatment duration, and overall survival. Nonetheless, when key parameters are varied within plausible ranges, all three treatments always remain poor value for money. CONCLUSIONS: All three treatments are highly unlikely to be considered cost-effective in this patient population in the United Kingdom. We explain how the reader can adapt the model for other countries.


Assuntos
Anticorpos Monoclonais/economia , Camptotecina/análogos & derivados , Neoplasias Colorretais/economia , Resistencia a Medicamentos Antineoplásicos/genética , Proteínas Proto-Oncogênicas/genética , Proteínas ras/genética , Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais/uso terapêutico , Anticorpos Monoclonais Humanizados , Antineoplásicos/economia , Antineoplásicos/uso terapêutico , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/economia , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Camptotecina/administração & dosagem , Camptotecina/economia , Camptotecina/uso terapêutico , Cetuximab , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Análise Custo-Benefício , Receptores ErbB/efeitos dos fármacos , Receptores ErbB/genética , Humanos , Irinotecano , Mutação , Metástase Neoplásica , Panitumumabe , Proteínas Proto-Oncogênicas p21(ras) , Anos de Vida Ajustados por Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Terapia de Salvação/economia , Medicina Estatal/economia , Análise de Sobrevida , Reino Unido
5.
Orphanet J Rare Dis ; 16(1): 255, 2021 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-34082807

RESUMO

BACKGROUND: Progressive familial intrahepatic cholestasis is a rare, heterogeneous group of liver disorders of autosomal recessive inheritance, characterised by an early onset of cholestasis with pruritus and malabsorption, which rapidly progresses, eventually culminating in liver failure. For children and their parents, PFIC is an extremely distressing disease. Significant pruritus can lead to severe cutaneous mutilation and may affect many activities of daily living through loss of sleep, irritability, poor attention, and impaired school performance. METHODS: Databases including MEDLINE and Embase were searched for publications on PFIC prevalence, incidence or natural history, and the economic burden or health-related quality of life of patients with PFIC. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed. RESULTS: Three systematic reviews and twenty-two studies were eligible for inclusion for the epidemiology of PFIC including a total of 2603 patients. Study periods ranged from 3 to 33 years. Local population prevalence of PFIC was reported in three studies, ranging from 9.0 to 12.0% of children admitted with cholestasis, acute liver failure, or splenomegaly. The most detailed data come from the NAPPED study where native liver survival of >15 years is predicted in PFIC2 patients with a serum bile  acid concentration below 102 µmol/L following bile diversion surgery. Burden of disease was mainly reported through health-related quality of life (HRQL), rates of surgery and survival. Rates of biliary diversion and liver transplant varied widely depending on study period, sample size and PFIC type, with many patients have multiple surgeries and progressing to liver transplant. This renders data unsuitable for comparison. CONCLUSION: Using robust and transparent methods, this systematic review summarises our current knowledge of PFIC. The epidemiological overview is highly mixed and dependent on presentation and PFIC subtype. Only two studies reported HRQL and mortality results were variable across different subtypes. Lack of data and extensive heterogeneity severely limit understanding across this disease area, particularly variation around and within subtypes.


Assuntos
Colestase Intra-Hepática , Colestase , Atividades Cotidianas , Criança , Colestase Intra-Hepática/epidemiologia , Colestase Intra-Hepática/genética , Humanos , Qualidade de Vida
6.
Pharmacoeconomics ; 36(1): 39-49, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-28914440

RESUMO

The manufacturer of olaratumab (Lartruvo®), Eli Lilly & Company Limited, submitted evidence for the clinical and cost effectiveness of this drug, in combination with doxorubicin, for untreated advanced soft tissue sarcoma (STS) not amenable to surgery or radiotherapy, as part of the National Institute for Health and Care Excellence (NICE) Single Technology Appraisal process. The Peninsula Technology Assessment Group, commissioned to act as the Evidence Review Group (ERG), critically reviewed the company's submission. Clinical effectiveness evidence for the company's analysis was derived from an open-label, randomised controlled trial, JGDG. The analysis was based on a partitioned survival model with a time horizon of 25 years, and the perspective was of the UK National Health Service (NHS) and Personal Social Services. Costs and benefits were discounted at 3.5% per year. Given the available evidence, olaratumab is likely to meet NICE's end-of-life criteria. To improve the cost effectiveness of olaratumab, the company offered a discount through a Commercial Access Agreement (CAA) with the NHS England. When the discount was applied, the mean base-case and probabilistic incremental cost-effectiveness ratios (ICERs) for olaratumab plus doxorubicin versus the standard-of-care doxorubicin were £46,076 and £47,127 per quality-adjusted life-year (QALY) gained, respectively; the probability of this treatment being cost effective at the willingness-to-pay threshold of £50,000 per QALY gained, applicable to end-of-life treatments, was 0.54. The respective ICERs from the ERG's analysis were approximately £60,000/QALY gained, and the probability of the treatment being cost effective was 0.21. In August 2017, the NICE Appraisal Committee recommended olaratumab in combination with doxorubicin for this indication for use via the UK Cancer Drugs Fund under the agreed CAA until further evidence being collected in the ongoing phase III trial-ANNOUNCE-becomes available in December 2020.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Sarcoma/tratamento farmacológico , Anticorpos Monoclonais/administração & dosagem , Protocolos de Quimioterapia Combinada Antineoplásica/economia , Análise Custo-Benefício , Doxorrubicina/administração & dosagem , Humanos , Anos de Vida Ajustados por Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Sarcoma/economia , Avaliação da Tecnologia Biomédica/métodos
8.
Health Technol Assess ; 21(51): 1-238, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28895526

RESUMO

BACKGROUND: Inherited mutations in deoxyribonucleic acid (DNA) mismatch repair (MMR) genes lead to an increased risk of colorectal cancer (CRC), gynaecological cancers and other cancers, known as Lynch syndrome (LS). Risk-reducing interventions can be offered to individuals with known LS-causing mutations. The mutations can be identified by comprehensive testing of the MMR genes, but this would be prohibitively expensive in the general population. Tumour-based tests - microsatellite instability (MSI) and MMR immunohistochemistry (IHC) - are used in CRC patients to identify individuals at high risk of LS for genetic testing. MLH1 (MutL homologue 1) promoter methylation and BRAF V600E testing can be conducted on tumour material to rule out certain sporadic cancers. OBJECTIVES: To investigate whether testing for LS in CRC patients using MSI or IHC (with or without MLH1 promoter methylation testing and BRAF V600E testing) is clinically effective (in terms of identifying Lynch syndrome and improving outcomes for patients) and represents a cost-effective use of NHS resources. REVIEW METHODS: Systematic reviews were conducted of the published literature on diagnostic test accuracy studies of MSI and/or IHC testing for LS, end-to-end studies of screening for LS in CRC patients and economic evaluations of screening for LS in CRC patients. A model-based economic evaluation was conducted to extrapolate long-term outcomes from the results of the diagnostic test accuracy review. The model was extended from a model previously developed by the authors. RESULTS: Ten studies were identified that evaluated the diagnostic test accuracy of MSI and/or IHC testing for identifying LS in CRC patients. For MSI testing, sensitivity ranged from 66.7% to 100.0% and specificity ranged from 61.1% to 92.5%. For IHC, sensitivity ranged from 80.8% to 100.0% and specificity ranged from 80.5% to 91.9%. When tumours showing low levels of MSI were treated as a positive result, the sensitivity of MSI testing increased but specificity fell. No end-to-end studies of screening for LS in CRC patients were identified. Nine economic evaluations of screening for LS in CRC were identified. None of the included studies fully matched the decision problem and hence a new economic evaluation was required. The base-case results in the economic evaluation suggest that screening for LS in CRC patients using IHC, BRAF V600E and MLH1 promoter methylation testing would be cost-effective at a threshold of £20,000 per quality-adjusted life-year (QALY). The incremental cost-effectiveness ratio for this strategy was £11,008 per QALY compared with no screening. Screening without tumour tests is not predicted to be cost-effective. LIMITATIONS: Most of the diagnostic test accuracy studies identified were rated as having a risk of bias or were conducted in unrepresentative samples. There was no direct evidence that screening improves long-term outcomes. No probabilistic sensitivity analysis was conducted. CONCLUSIONS: Systematic review evidence suggests that MSI- and IHC-based testing can be used to identify LS in CRC patients, although there was heterogeneity in the methods used in the studies identified and the results of the studies. There was no high-quality empirical evidence that screening improves long-term outcomes and so an evidence linkage approach using modelling was necessary. Key determinants of whether or not screening is cost-effective are the accuracy of tumour-based tests, CRC risk without surveillance, the number of relatives identified for cascade testing, colonoscopic surveillance effectiveness and the acceptance of genetic testing. Future work should investigate screening for more causes of hereditary CRC and screening for LS in endometrial cancer patients. STUDY REGISTRATION: This study is registered as PROSPERO CRD42016033879. FUNDING: The National Institute for Health Research Health Technology Assessment programme.


Assuntos
Neoplasias Colorretais Hereditárias sem Polipose/genética , Análise Custo-Benefício , Testes Genéticos , Neoplasias Colorretais Hereditárias sem Polipose/economia , Reparo de Erro de Pareamento de DNA , Neoplasias do Endométrio , Inglaterra , Feminino , Testes Genéticos/economia , Testes Genéticos/métodos , Humanos , Instabilidade de Microssatélites , Anos de Vida Ajustados por Qualidade de Vida
9.
Health Technol Assess ; 20(61): 1-324, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27557331

RESUMO

BACKGROUND: End-stage renal disease is a long-term irreversible decline in kidney function requiring kidney transplantation, haemodialysis or peritoneal dialysis. The preferred option is kidney transplantation followed by induction and maintenance immunosuppressive therapy to reduce the risk of kidney rejection and prolong graft survival. OBJECTIVES: To systematically review and update the evidence for the clinical effectiveness and cost-effectiveness of basiliximab (BAS) (Simulect,(®) Novartis Pharmaceuticals) and rabbit antihuman thymocyte immunoglobulin (Thymoglobuline,(®) Sanofi) as induction therapy and immediate-release tacrolimus [Adoport(®) (Sandoz); Capexion(®) (Mylan); Modigraf(®) (Astellas Pharma); Perixis(®) (Accord Healthcare); Prograf(®) (Astellas Pharma); Tacni(®) (Teva); Vivadex(®) (Dexcel Pharma)], prolonged-release tacrolimus (Advagraf,(®) Astellas Pharma); belatacept (BEL) (Nulojix,(®) Bristol-Myers Squibb), mycophenolate mofetil (MMF) [Arzip(®) (Zentiva), CellCept(®) (Roche Products), Myfenax(®) (Teva), generic MMF is manufactured by Accord Healthcare, Actavis, Arrow Pharmaceuticals, Dr Reddy's Laboratories, Mylan, Sandoz and Wockhardt], mycophenolate sodium, sirolimus (Rapamune,(®) Pfizer) and everolimus (Certican,(®) Novartis Pharmaceuticals) as maintenance therapy in children and adolescents undergoing renal transplantation. DATA SOURCES: Clinical effectiveness searches were conducted to 7 January 2015 in MEDLINE (via Ovid), EMBASE (via Ovid), Cochrane Central Register of Controlled Trials (via Wiley Online Library) and Web of Science [via Institute for Scientific Information (ISI)], Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects and Health Technology Assessment (HTA) (The Cochrane Library via Wiley Online Library) and Health Management Information Consortium (via Ovid). Cost-effectiveness searches were conducted to 15 January 2015 using a costs or economic literature search filter in MEDLINE (via Ovid), EMBASE (via Ovid), NHS Economic Evaluation Databases (via Wiley Online Library), Web of Science (via ISI), Health Economic Evaluations Database (via Wiley Online Library) and EconLit (via EBSCOhost). REVIEW METHODS: Titles and abstracts were screened according to predefined inclusion criteria, as were full texts of identified studies. Included studies were extracted and quality appraised. Data were meta-analysed when appropriate. A new discrete time state transition economic model (semi-Markov) was developed; graft function, and incidences of acute rejection and new-onset diabetes mellitus were used to extrapolate graft survival. Recipients were assumed to be in one of three health states: functioning graft, graft loss or death. RESULTS: Three randomised controlled trials (RCTs) and four non-RCTs were included. The RCTs only evaluated BAS and tacrolimus (TAC). No statistically significant differences in key outcomes were found between BAS and placebo/no induction. Statistically significantly higher graft function (p < 0.01) and less biopsy-proven acute rejection (odds ratio 0.29, 95% confidence interval 0.15 to 0.57) was found between TAC and ciclosporin (CSA). Only one cost-effectiveness study was identified, which informed NICE guidance TA99. BAS [with TAC and azathioprine (AZA)] was predicted to be cost-effective at £20,000-30,000 per quality-adjusted life year (QALY) versus no induction (BAS was dominant). BAS (with CSA and MMF) was not predicted to be cost-effective at £20,000-30,000 per QALY versus no induction (BAS was dominated). TAC (with AZA) was predicted to be cost-effective at £20,000-30,000 per QALY versus CSA (TAC was dominant). A model based on adult evidence suggests that at a cost-effectiveness threshold of £20,000-30,000 per QALY, BAS and TAC are cost-effective in all considered combinations; MMF was also cost-effective with CSA but not TAC. LIMITATIONS: The RCT evidence is very limited; analyses comparing all interventions need to rely on adult evidence. CONCLUSIONS: TAC is likely to be cost-effective (vs. CSA, in combination with AZA) at £20,000-30,000 per QALY. Analysis based on one RCT found BAS to be dominant, but analysis based on another RCT found BAS to be dominated. BAS plus TAC and AZA was predicted to be cost-effective at £20,000-30,000 per QALY when all regimens were compared using extrapolated adult evidence. High-quality primary effectiveness research is needed. The UK Renal Registry could form the basis for a prospective primary study. STUDY REGISTRATION: This study is registered as PROSPERO CRD42014013544. FUNDING: The National Institute for Health Research HTA programme.


Assuntos
Imunossupressores/economia , Imunossupressores/uso terapêutico , Falência Renal Crônica/cirurgia , Transplante de Rim/métodos , Abatacepte/uso terapêutico , Anticorpos Monoclonais/economia , Anticorpos Monoclonais/uso terapêutico , Soro Antilinfocitário/uso terapêutico , Azatioprina/economia , Azatioprina/uso terapêutico , Basiliximab , Criança , Ensaios Clínicos como Assunto , Análise Custo-Benefício , Quimioterapia Combinada , Everolimo/uso terapêutico , Humanos , Imunossupressores/administração & dosagem , Imunossupressores/efeitos adversos , Modelos Econômicos , Ácido Micofenólico/uso terapêutico , Proteínas Recombinantes de Fusão/economia , Proteínas Recombinantes de Fusão/uso terapêutico , Sirolimo/uso terapêutico , Tacrolimo/economia , Tacrolimo/uso terapêutico , Avaliação da Tecnologia Biomédica
10.
Health Technol Assess ; 20(13): 1-588, v-vi, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26907163

RESUMO

BACKGROUND: Anaemia is a common side effect of cancer treatments and can lead to a reduction in quality of life. Erythropoiesis-stimulating agents (ESAs) are licensed for use in conjunction with red blood cell transfusions to improve cancer treatment-induced anaemia (CIA). OBJECTIVE: To investigate the effectiveness and cost-effectiveness of ESAs in anaemia associated with cancer treatment (specifically chemotherapy). DATA SOURCES: The following databases were searched from 2004 to 2013: The Cochrane Library, MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, Web of Science, Cumulative Index to Nursing and Allied Health Literature, British Nursing Index, Health Management Information Consortium, Current Controlled Trials and ClinicalTrials.gov. The US Food and Drug Administration and European Medicines Agency websites were also searched. Bibliographies of included papers were scrutinised for further potentially includable studies. REVIEW METHODS: The clinical effectiveness review followed principles published by the NHS Centre for Reviews and Dissemination. Randomised controlled trials (RCTs), or systematic reviews of RCTs, of ESAs (epoetin or darbepoetin) for treating people with CIA were eligible for inclusion in the review. Comparators were best supportive care, placebo or other ESAs. Anaemia- and malignancy-related outcomes, health-related quality of life (HRQoL) and adverse events (AEs) were evaluated. When appropriate, data were pooled using meta-analysis. An empirical health economic model was developed comparing ESA treatment with no ESA treatment. The model comprised two components: one evaluating short-term costs and quality-adjusted life-years (QALYs) (while patients are anaemic) and one evaluating long-term QALYs. Costs and benefits were discounted at 3.5% per annum. Probabilistic and univariate deterministic sensitivity analyses were performed. RESULTS: Of 1457 titles and abstracts screened, 23 studies assessing ESAs within their licensed indication (based on start dose administered) were included in the review. None of the RCTs were completely aligned with current European Union licenses. The results suggest a clinical benefit from ESAs for anaemia-related outcomes and an improvement in HRQoL scores. The impact of ESAs on AEs and survival remains highly uncertain, although point estimates are lower, confidence intervals are wide and not statistically significant. Base-case incremental cost-effectiveness ratios (ICERs) for ESA treatment compared with no ESA treatment ranged from £ 19,429 to £ 35,018 per QALY gained, but sensitivity and scenario analyses demonstrate considerable uncertainty in these ICERs, including the possibility of overall health disbenefit. All ICERs were sensitive to survival and cost. LIMITATIONS: The relative effectiveness of ESAs was not addressed; all ESAs were assumed to have equivalent efficacy. No studies were completely aligned with their European labelling beyond the starting dose evaluated. There is questionable generalisability given that the included trials were published >20 years ago and there have been many changes to chemotherapy as well as to the quality of supportive treatment. Trial quality was moderate or poor and there was considerable unexplained heterogeneity for a number of outcomes, particularly survival, and evidence of publication bias. Adjustments were not made to account for multiple testing. CONCLUSIONS: ESAs could be cost-effective when used closer to licence, but there is considerable uncertainty, mainly because of unknown impacts on overall survival. STUDY REGISTRATION: This study is registered as PROSPERO CRD42013005812. FUNDING: The National Institute for Health Research Health Technology Assessment programme.


Assuntos
Anemia/tratamento farmacológico , Análise Custo-Benefício , Hematínicos/uso terapêutico , Neoplasias/tratamento farmacológico , Avaliação da Tecnologia Biomédica , Anemia/economia , Anemia/etiologia , Hematínicos/economia , Humanos , Modelos Econômicos , Neoplasias/economia , Anos de Vida Ajustados por Qualidade de Vida
11.
Health Technol Assess ; 20(62): 1-594, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-27578428

RESUMO

BACKGROUND: End-stage renal disease is a long-term irreversible decline in kidney function requiring renal replacement therapy: kidney transplantation, haemodialysis or peritoneal dialysis. The preferred option is kidney transplantation, followed by immunosuppressive therapy (induction and maintenance therapy) to reduce the risk of kidney rejection and prolong graft survival. OBJECTIVES: To review and update the evidence for the clinical effectiveness and cost-effectiveness of basiliximab (BAS) (Simulect(®), Novartis Pharmaceuticals UK Ltd) and rabbit anti-human thymocyte immunoglobulin (rATG) (Thymoglobulin(®), Sanofi) as induction therapy, and immediate-release tacrolimus (TAC) (Adoport(®), Sandoz; Capexion(®), Mylan; Modigraf(®), Astellas Pharma; Perixis(®), Accord Healthcare; Prograf(®), Astellas Pharma; Tacni(®), Teva; Vivadex(®), Dexcel Pharma), prolonged-release tacrolimus (Advagraf(®) Astellas Pharma), belatacept (BEL) (Nulojix(®), Bristol-Myers Squibb), mycophenolate mofetil (MMF) (Arzip(®), Zentiva; CellCept(®), Roche Products; Myfenax(®), Teva), mycophenolate sodium (MPS) (Myfortic(®), Novartis Pharmaceuticals UK Ltd), sirolimus (SRL) (Rapamune(®), Pfizer) and everolimus (EVL) (Certican(®), Novartis) as maintenance therapy in adult renal transplantation. METHODS: Clinical effectiveness searches were conducted until 18 November 2014 in MEDLINE (via Ovid), EMBASE (via Ovid), Cochrane Central Register of Controlled Trials (via Wiley Online Library) and Web of Science (via ISI), Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects and Health Technology Assessment (The Cochrane Library via Wiley Online Library) and Health Management Information Consortium (via Ovid). Cost-effectiveness searches were conducted until 18 November 2014 using a costs or economic literature search filter in MEDLINE (via Ovid), EMBASE (via Ovid), NHS Economic Evaluation Database (via Wiley Online Library), Web of Science (via ISI), Health Economic Evaluations Database (via Wiley Online Library) and the American Economic Association's electronic bibliography (via EconLit, EBSCOhost). Included studies were selected according to predefined methods and criteria. A random-effects model was used to analyse clinical effectiveness data (odds ratios for binary data and mean differences for continuous data). Network meta-analyses were undertaken within a Bayesian framework. A new discrete time-state transition economic model (semi-Markov) was developed, with acute rejection, graft function (GRF) and new-onset diabetes mellitus used to extrapolate graft survival. Recipients were assumed to be in one of three health states: functioning graft, graft loss or death. RESULTS: Eighty-nine randomised controlled trials (RCTs), of variable quality, were included. For induction therapy, no treatment appeared more effective than another in reducing graft loss or mortality. Compared with placebo/no induction, rATG and BAS appeared more effective in reducing biopsy-proven acute rejection (BPAR) and BAS appeared more effective at improving GRF. For maintenance therapy, no treatment was better for all outcomes and no treatment appeared most effective at reducing graft loss. BEL + MMF appeared more effective than TAC + MMF and SRL + MMF at reducing mortality. MMF + CSA (ciclosporin), TAC + MMF, SRL + TAC, TAC + AZA (azathioprine) and EVL + CSA appeared more effective than CSA + AZA and EVL + MPS at reducing BPAR. SRL + AZA, TAC + AZA, TAC + MMF and BEL + MMF appeared to improve GRF compared with CSA + AZA and MMF + CSA. In the base-case deterministic and probabilistic analyses, BAS, MMF and TAC were predicted to be cost-effective at £20,000 and £30,000 per quality-adjusted life-year (QALY). When comparing all regimens, only BAS + TAC + MMF was cost-effective at £20,000 and £30,000 per QALY. LIMITATIONS: For included trials, there was substantial methodological heterogeneity, few trials reported follow-up beyond 1 year, and there were insufficient data to perform subgroup analysis. Treatment discontinuation and switching were not modelled. FUTURE WORK: High-quality, better-reported, longer-term RCTs are needed. Ideally, these would be sufficiently powered for subgroup analysis and include health-related quality of life as an outcome. CONCLUSION: Only a regimen of BAS induction followed by maintenance with TAC and MMF is likely to be cost-effective at £20,000-30,000 per QALY. STUDY REGISTRATION: This study is registered as PROSPERO CRD42014013189. FUNDING: The National Institute for Health Research Health Technology Assessment programme.


Assuntos
Imunossupressores/economia , Imunossupressores/uso terapêutico , Falência Renal Crônica/cirurgia , Transplante de Rim/métodos , Abatacepte/economia , Abatacepte/uso terapêutico , Anticorpos Monoclonais , Soro Antilinfocitário , Basiliximab , Teorema de Bayes , Análise Custo-Benefício , Everolimo/economia , Everolimo/uso terapêutico , Rejeição de Enxerto/prevenção & controle , Humanos , Imunossupressores/administração & dosagem , Imunossupressores/efeitos adversos , Modelos Econômicos , Ácido Micofenólico/economia , Ácido Micofenólico/uso terapêutico , Qualidade de Vida , Anos de Vida Ajustados por Qualidade de Vida , Ensaios Clínicos Controlados Aleatórios como Assunto , Proteínas Recombinantes de Fusão , Sirolimo/economia , Sirolimo/uso terapêutico , Tacrolimo/economia , Tacrolimo/uso terapêutico , Avaliação da Tecnologia Biomédica
12.
BMJ ; 350: h15, 2015 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-25646632

RESUMO

OBJECTIVE: To obtain summary estimates of the accuracy of a single baseline measurement of the Elecsys Troponin T high-sensitive assay (Roche Diagnostics) for the diagnosis of acute myocardial infarction in patients presenting to the emergency department. DESIGN: Systematic review and meta-analysis of diagnostic test accuracy studies. DATA SOURCES: Medline, Embase, and other relevant electronic databases were searched for papers published between January 2006 and December 2013. STUDY SELECTION: Studies were included if they evaluated the diagnostic accuracy of a single baseline measurement of Elecsys Troponin T high-sensitive assay for the diagnosis of acute myocardial infarction in patients presenting to the emergency department with suspected acute coronary syndrome. STUDY APPRAISAL AND DATA SYNTHESIS: The first author screened all titles and abstracts identified through the searches and selected all potentially relevant papers. The screening of the full texts, the data extraction, and the methodological quality assessment, using the adapted QUADAS-2 tool, were conducted independently by two reviewers with disagreements being resolved through discussion or arbitration. If appropriate, meta-analysis was conducted using the hierarchical bivariate model. RESULTS: Twenty three studies reported the performance of the evaluated assay at presentation. The results for 14 ng/L and 3-5 ng/L cut-off values were pooled separately. At 14 ng/L (20 papers), the summary sensitivity was 89.5% (95% confidence interval 86.3% to 92.1%) and the summary specificity was 77.1% (68.7% to 83.7%). At 3-5 ng/L (six papers), the summary sensitivity was 97.4% (94.9% to 98.7%) and the summary specificity was 42.4% (31.2% to 54.5%). This means that if 21 of 100 consecutive patients have the target condition (21%, the median prevalence across the studies), 2 (95% confidence interval 2 to 3) of 21 patients with acute myocardial infarction will be missed (false negatives) if 14 ng/L is used as a cut-off value and 18 (13 to 25) of 79 patients without acute myocardial infarction will test positive (false positives). If the 3-5 ng/L cut-off value is used, <1 (0 to 1) patient with acute myocardial infarction will be missed and 46 (36 to 54) patients without acute myocardial infarction will test positive. CONCLUSIONS: The results indicate that a single baseline measurement of the Elecsys Troponin T high-sensitive assay could be used to rule out acute myocardial infarction if lower cut-off values such as 3 ng/L or 5 ng/L are used. However, this method should be part of a comprehensive triage strategy and may not be appropriate for patients who present less than three hours after symptom onset. Care must also be exercised because of the higher imprecision of the evaluated assay and the greater effect of lot-to-lot reagent variation at low troponin concentrations. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration number CRD42013003926.


Assuntos
Infarto do Miocárdio/sangue , Troponina T/sangue , Biomarcadores/sangue , Serviço Hospitalar de Emergência , Humanos , Valor Preditivo dos Testes , Sensibilidade e Especificidade
13.
Health Technol Assess ; 19(2): v-xxv, 1-215, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25586547

RESUMO

BACKGROUND: In breast cancer patients, sentinel lymph node biopsy is carried out at the same time as the removal of the primary tumour to postoperatively test with histopathology for regional metastases in the sentinel lymph node. Those patients with positive test results are then operated on 2-4 weeks after primary surgery to remove the lymph nodes from the axilla (axillary lymph node dissection, ALND). New molecular tests RD-100i [one-step nucleic acid amplification (OSNA); based on messenger RNA amplification to identify the cytokeratin-19 (CK19) gene marker] (Sysmex, Norderstedt, Germany) and Metasin (using the CK19 and mammaglobin gene markers) (Cellular Pathology, Princess Alexandra Hospital NHS Trust, Harlow, UK) are intended to provide an intraoperative diagnosis, thereby avoiding the need for postoperative histopathology and, in positive cases, a second operation for ALND. OBJECTIVE: To evaluate the clinical effectiveness and cost-effectiveness of using OSNA and Metasin in the NHS in England for the intraoperative diagnosis of sentinel lymph nodes metastases, compared with postoperative histopathology, the current standard. DATA SOURCES: Electronic databases including MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, EMBASE, The Cochrane Library and the Health Economic Evaluations Database as well as clinical trial registries, grey literature and conference proceedings were searched up to July 2012. REVIEW METHODS: A systematic review of the evidence was carried out using standard methods. Single-gate studies were used to estimate the accuracy of OSNA with histopathology as the reference standard. The cost-effectiveness analysis adapted an existing simulation model of the long-term costs and health implications of early breast cancer diagnostic outcomes. The model accounted for the costs of an extended first operation with intraoperative testing, the loss of health-related quality of life (disutility) from waiting for postoperative test results, disutility and costs of a second operation, and long-term costs and disutility from lymphoedema related to ALND, adjuvant therapy, locoregional recurrence and metastatic recurrence. RESULTS: A total of 724 references were identified in the searches, of which 17 studies assessing test accuracy were included in the review, 15 on OSNA and two on Metasin. Both Metasin studies were unpublished. OSNA sensitivity of 84.5% [95% confidence interval (CI) 74.7% to 91.0%] and specificity of 91.8% (95% CI 87.8% to 94.6%) for patient nodal status were estimated in a meta-analysis of five studies [unadjusted for tissue allocation bias (TAB)]. At these values and a 20% node-positive rate, OSNA resulted in lifetime discounted cost-savings of £498 and a quality-adjusted life-year (QALY) loss of 0.048 relative to histopathology, that is, £4324 saved per QALY lost. The most favourable plausible scenario for OSNA in terms of the node-positive rate (range 10-40%), diagnostic accuracy values (91.3% sensitivity and 94.2% specificity, from three reports that adjusted for TAB), the costs of histopathology, OSNA and second surgery, and long-term costs and utilities resulted in a maximum saving per QALY lost of £10,500; OSNA sensitivity and specificity would need to be ≥ 95% for this figure to be ≥ £20,000. LIMITATIONS: There is limited evidence on the diagnostic test accuracy of intraoperative tests. The quality of information on costs of resource utilisation during the diagnostic pathway is low and no evidence exists on the disutility of waiting for a second surgery. No comparative studies exist that report clinical outcomes of intraoperative diagnostic tests. These knowledge gaps have more influence on the decision than current uncertainty in the performance of postoperative histopathology in standard practice. CONCLUSIONS: One-step nucleic acid amplification is not cost-effective for the intraoperative diagnosis of sentinel lymph node metastases. OSNA is less accurate than histopathology and the consequent loss of health benefits in this patient group is not compensated for by health gains elsewhere in the health system that may be obtained with the cost-savings made. The evidence on Metasin is insufficient to evaluate its cost-effectiveness. STUDY REGISTRATION: This study is registered as PROSPERO CRD42012002889. FUNDING: The National Institute for Health Research Health Technology Assessment programme.


Assuntos
Neoplasias da Mama/patologia , Linfonodos/patologia , Técnicas de Amplificação de Ácido Nucleico/métodos , Axila , Análise Custo-Benefício , Inglaterra , Humanos , Período Intraoperatório , Metástase Linfática , Qualidade de Vida , Anos de Vida Ajustados por Qualidade de Vida , Sensibilidade e Especificidade , Biópsia de Linfonodo Sentinela , Medicina Estatal
14.
Health Technol Assess ; 18(58): 1-406, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-25244061

RESUMO

BACKGROUND: Lynch syndrome (LS) is an inherited autosomal dominant disorder characterised by an increased risk of colorectal cancer (CRC) and other cancers, and caused by mutations in the deoxyribonucleic acid (DNA) mismatch repair genes. OBJECTIVE: To evaluate the accuracy and cost-effectiveness of strategies to identify LS in newly diagnosed early-onset CRC patients (aged < 50 years). Cascade testing of relatives is employed in all strategies for individuals in whom LS is identified. DATA SOURCES AND METHODS: Systematic reviews were conducted of the test accuracy of microsatellite instability (MSI) testing or immunohistochemistry (IHC) in individuals with CRC at risk of LS, and of economic evidence relating to diagnostic strategies for LS. Reviews were carried out in April 2012 (test accuracy); and in February 2012, repeated in February 2013 (economic evaluations). Databases searched included MEDLINE (1946 to April week 3, 2012), EMBASE (1980 to week 17, 2012) and Web of Science (inception to 30 April 2012), and risk of bias for test accuracy was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) quality appraisal tool. A de novo economic model of diagnostic strategies for LS was developed. RESULTS: Inconsistencies in study designs precluded pooling of diagnostic test accuracy results from a previous systematic review and nine subsequent primary studies. These were of mixed quality, with significant methodological concerns identified for most. IHC and MSI can both play a part in diagnosing LS but neither is gold standard. No UK studies evaluated the cost-effectiveness of diagnosing and managing LS, although studies from other countries generally found some strategies to be cost-effective compared with no testing. The de novo model demonstrated that all strategies were cost-effective compared with no testing at a threshold of £20,000 per quality-adjusted life-year (QALY), with the most cost-effective strategy utilising MSI and BRAF testing [incremental cost-effectiveness ratio (ICER) = £5491 per QALY]. The maximum health benefit to the population of interest would be obtained using universal germline testing, but this would not be a cost-effective use of NHS resources compared with the next best strategy. When the age limit was raised from 50 to 60 and 70 years, the ICERs compared with no testing increased but remained below £20,000 per QALY (except for universal germline testing with an age limit of 70 years). The total net health benefit increased with the age limit as more individuals with LS were identified. Uncertainty was evaluated through univariate sensitivity analyses, which suggested that the parameters substantially affecting cost-effectiveness: were the risk of CRC for individuals with LS; the average number of relatives identified per index patient; the effectiveness of colonoscopy in preventing metachronous CRC; the cost of colonoscopy; the duration of the psychological impact of genetic testing on health-related quality of life (HRQoL); and the impact of prophylactic hysterectomy and bilateral salpingo-oophorectomy on HRQoL (this had the potential to make all testing strategies more expensive and less effective than no testing). LIMITATIONS: The absence of high-quality data for the impact of prophylactic gynaecological surgery and the psychological impact of genetic testing on HRQoL is an acknowledged limitation. CONCLUSIONS: Results suggest that reflex testing for LS in newly diagnosed CRC patients aged < 50 years is cost-effective. Such testing may also be cost-effective in newly diagnosed CRC patients aged < 60 or < 70 years. Results are subject to uncertainty due to a number of parameters, for some of which good estimates were not identified. We recommend future research to estimate the cost-effectiveness of testing for LS in individuals with newly diagnosed endometrial or ovarian cancer, and the inclusion of aspirin chemoprevention. Further research is required to accurately estimate the impact of interventions on HRQoL. STUDY REGISTRATION: This study is registered as PROSPERO CRD42012002436. FUNDING: The National Institute for Health Research Health Technology Assessment programme.


Assuntos
Neoplasias Colorretais Hereditárias sem Polipose/diagnóstico , Idoso , Neoplasias Colorretais Hereditárias sem Polipose/economia , Neoplasias Colorretais Hereditárias sem Polipose/genética , Análise Custo-Benefício , Testes Genéticos/economia , Testes Genéticos/métodos , Humanos , Pessoa de Meia-Idade
15.
Implement Sci ; 7: 91, 2012 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-22978693

RESUMO

BACKGROUND: More than a third of people over the age of 65 years fall each year. Falling can lead to a reduction in quality of life, mortality, and a risk of prolonged hospitalisation. Reducing and preventing falls has become an international health priority. To help understand why research evidence has often not been translated into changes in clinical practice, we undertook a systematic review and synthesis of qualitative research in order to identify what factors serve as barriers and facilitators to the successful implementation of fall-prevention programmes. METHODS: We conducted a review of literature published between 1980 and January 2012 for qualitative research studies that examined barriers and facilitators to the effective implementation of fall-prevention interventions among community-dwelling older people and healthcare professionals. Two reviewers independently screened studies for inclusion, extracted data, and assessed methodological quality according to predefined criteria. Findings were synthesised using meta-ethnography. RESULTS: Of the 5010 articles identified through database searching, 19 were included in the review. Analysis of the 19 studies revealed limited information about the mechanisms by which barriers to implementation of fall-prevention interventions had been overcome. Data synthesis produced three overarching concepts: (1) practical considerations, (2) adapting for community, and (3) psychosocial. A line of argument synthesis describes the barriers and facilitators to the successful implementation of fall-prevention programmes. These concepts show that the implementation of fall-prevention programmes is complex and multifactorial. This is the first systematic review and synthesis of qualitative studies to examine factors influencing the implementation of fall-prevention programmes from the perspectives of both the healthcare professional and the community-dwelling older person. CONCLUSIONS: The current literature on barriers and facilitators to the implementation of fall-prevention programmes examines a variety of interventions. However, the ways in which the interventions are reported suggests there are substantial methodological challenges that often inhibit implementation into practice. We recommend that successful implementation requires individuals, professionals, and organisations to modify established behaviours, thoughts, and practice. The issues identified through this synthesis need to be fully considered and addressed if fall-prevention programmes are to be successfully implemented into clinical practice.


Assuntos
Acidentes por Quedas/prevenção & controle , Prevenção de Acidentes/economia , Prevenção de Acidentes/métodos , Acidentes por Quedas/economia , Idoso , Atitude Frente a Saúde , Custos e Análise de Custo , Atenção à Saúde , Acessibilidade aos Serviços de Saúde , Humanos , Equipamentos Ortopédicos , Qualidade de Vida , Autoimagem , Fatores de Tempo
16.
J Safety Res ; 42(6): 443-51, 2011 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-22152262

RESUMO

PROBLEM AND OBJECTIVE: The translation of the evidence-base for preventing falls among community-dwelling older people into practice has been limited. This study systematically reviewed and synthesised the effectiveness of methods to implement falls prevention programmes with this population. METHODS: Articles published between 1980 and May 2010 that evaluated the effects of an implementation strategy. No design restrictions were imposed. A narrative synthesis was undertaken. RESULTS: 15 studies were identified. Interventions that involved the active training of healthcare professionals improved implementation. The evidence around changing the way people who fall are managed within primary care practices, and, layperson, peer or community delivered models was mixed. IMPACT ON INDUSTRY: Translating the evidence-base into practice involves changing the attitudes and behaviours of older people, healthcare professionals and organisations. However, there is a need for further evaluation on how this can be best achieved.


Assuntos
Prevenção de Acidentes/métodos , Acidentes por Quedas/prevenção & controle , Medicina Baseada em Evidências , Vida Independente , Idoso , Idoso de 80 Anos ou mais , Humanos , Pesquisa Translacional Biomédica
17.
Environ Sci Technol ; 39(6): 1688-97, 2005 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-15819226

RESUMO

The sorption of an anionic surfactant (sodium dodecyl sulfate; SDS) and a cationic surfactant (hexadecyl trimethylammonium bromide; HDTMA) to estuarine sediment has been studied in river water and seawater. Sorption isotherms for SDS were essentially linear in both waters, suggesting a nonspecific, hydrophobic interaction between the SDS tail and particle surface. Sorption of HDTMA was considerably greater, more nonlinear, and more sensitive to water composition. These observations were attributed to a combination of both electrostatic and hydrophobic interactions between the surfactant and particle surface, the formation of admicelles, and salinity-induced structural alteration of the hydrophobic tail of the HDTMA molecule. Presence of SDS caused a reduction in the sorption of phenanthrene to estuarine sediment because of the competitive effects of the surfactant tail for hydrophobic sorption sites on the particle surface. Conversely, the presence of HDTMA caused significant enhancement in phenanthrene sequestration because of head-on sorption of surfactant molecules and a resulting, more hydrophobic particle surface. The most persistent feature of our results was an inverse dependence of unit sorption on particle concentration, and an empirical algorithm defining the effect was used to calculate the sediment-water fractionation of realistic concentrations of reactants in the estuarine water column. The results of these calculations, and the more general findings of this study, significantly improve our understanding of both the transport and fate of ionic surfactants in the estuarine environment, and the effects that these surfactants have on the partitioning of hydrophobic organic micropollutants.


Assuntos
Compostos de Cetrimônio/química , Sedimentos Geológicos/química , Fenantrenos/química , Dodecilsulfato de Sódio/química , Tensoativos/química , Adsorção , Cetrimônio , Ecossistema , Tamanho da Partícula , Água/química
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