Anticholinergic burden (prognostic factor) for prediction of dementia or cognitive decline in older adults with no known cognitive syndrome.

BACKGROUND: Medications with anticholinergic properties are commonly prescribed to older adults. The cumulative anticholinergic effect of all the medications a person takes is referred to as the 'anticholinergic burden' because of its potential to cause adverse effects. It is possible that high anticholinergic burden may be a risk factor for development of cognitive decline or dementia. There are various scales available to measure anticholinergic burden but agreement between them is often poor. OBJECTIVES: To assess whether anticholinergic burden, as defined at the level of each individual scale, is a prognostic factor for future cognitive decline or dementia in cognitively unimpaired older adults. SEARCH METHODS: We searched the following databases from inception to 24 March 2021: MEDLINE (OvidSP), Embase (OvidSP), PsycINFO (OvidSP), CINAHL (EBSCOhost), and ISI Web of Science Core Collection (ISI Web of Science). SELECTION CRITERIA: We included prospective and retrospective longitudinal cohort and case-control observational studies with a minimum of one year' follow-up that examined the association between an anticholinergic burden measurement scale and future cognitive decline or dementia in cognitively unimpaired older adults. DATA COLLECTION AND ANALYSIS: Two review authors independently assessed studies for inclusion, and undertook data extraction, assessment of risk of bias, and GRADE assessment. We extracted odds ratios (OR) and hazard ratios, with 95% confidence intervals (CI), and linear data on the association between anticholinergic burden and cognitive decline or dementia. We intended to pool each metric separately; however, only OR-based data were suitable for pooling via a random-effects meta-analysis. We initially established adjusted and unadjusted pooled rates for each available anticholinergic scale; then, as an exploratory analysis, established pooled rates on the prespecified association across scales. We examined variability based on severity of anticholinergic burden. MAIN RESULTS: We identified 25 studies that met our inclusion criteria (968,428 older adults). Twenty studies were conducted in the community care setting, two in primary care clinics, and three in secondary care settings. Eight studies (320,906 participants) provided suitable data for meta-analysis. The Anticholinergic Cognitive Burden scale (ACB scale) was the only scale with sufficient data for 'scale-based' meta-analysis. Unadjusted ORs suggested an increased risk for cognitive decline or dementia in older adults with an anticholinergic burden (OR 1.47, 95% CI 1.09 to 1.96) and adjusted ORs similarly suggested an increased risk for anticholinergic burden, defined according to the ACB scale (OR 2.63, 95% CI 1.09 to 6.29). Exploratory analysis combining adjusted ORs across available scales supported these results (OR 2.16, 95% CI 1.38 to 3.38), and there was evidence of variability in risk based on severity of anticholinergic burden (ACB scale 1: OR 2.18, 95% CI 1.11 to 4.29; ACB scale 2: OR 2.71, 95% CI 2.01 to 3.56; ACB scale 3: OR 3.27, 95% CI 1.41 to 7.61); however, overall GRADE evaluation of certainty of the evidence was low. AUTHORS' CONCLUSIONS: There is low-certainty evidence that older adults without cognitive impairment who take medications with anticholinergic effects may be at increased risk of cognitive decline or dementia.

ANTECEDENTES: A los adultos mayores se les prescriben con frecuencia fármacos con propiedades anticolinérgicas. El efecto anticolinérgico acumulado de todos los fármacos que toma una persona se denomina "carga anticolinérgica" por su potencial para causar efectos adversos. Es posible que una alta carga anticolinérgica sea un factor de riesgo para la aparición de un deterioro cognitivo o la demencia. Existen varias escalas para medir la carga anticolinérgica, pero la concordancia entre ellas suele ser mala. OBJETIVOS: Evaluar si la carga anticolinérgica, definida a nivel de cada escala individual, es un factor pronóstico de un futuro deterioro cognitivo o demencia en adultos mayores sin deterioro cognitivo. MÉTODOS DE BÚSQUEDA: Se realizaron búsquedas en las siguientes bases de datos desde su creación hasta el 24 de marzo de 2021: MEDLINE (OvidSP), Embase (OvidSP), PsycINFO (OvidSP), CINAHL (EBSCOhost) e ISI Web of Science Core Collection (ISI Web of Science). CRITERIOS DE SELECCIÓN: Se incluyeron los estudios observacionales de cohortes y de casos y controles longitudinales prospectivos y retrospectivos con un seguimiento mínimo de un año, que examinaron la asociación entre una escala de medición de la carga anticolinérgica y el futuro deterioro cognitivo o demencia en adultos mayores sin deterioro cognitivo. OBTENCIÓN Y ANÁLISIS DE LOS DATOS: Dos autores de la revisión, de forma independiente, evaluaron los estudios para su inclusión y realizaron la extracción de los datos, la evaluación del riesgo de sesgo y la evaluación GRADE. Se extrajeron los odds ratios (OR) y los cociente de riesgos instantáneos, con intervalos de confianza (IC) del 95%, y los datos lineales sobre la asociación entre la carga anticolinérgica y el deterioro cognitivo o la demencia. La intención fue agrupar cada métrica por separado; sin embargo, sólo los datos basados en el OR fueron aptos para agruparlos mediante un metanálisis de efectos aleatorios. Inicialmente se establecieron las tasas agrupadas ajustadas y no ajustadas para cada escala anticolinérgica disponible; luego, como un análisis exploratorio, se establecieron las tasas agrupadas sobre la asociación predeterminada entre las escalas. Se examinó la variabilidad según la intensidad de la carga anticolinérgica. RESULTADOS PRINCIPALES: Se identificaron 25 estudios que cumplían los criterios de inclusión (968 428 adultos mayores). Veinte estudios se realizaron en ámbitos de atención comunitaria, dos en centros de atención primaria y tres en ámbitos de atención secundaria. Ocho estudios (320 906 participantes) proporcionaron datos adecuados para el metanálisis. La escala Anticholinergic Cognitive Burden (escala ACB) fue la única escala con datos suficientes para un metanálisis "basado en la escala". Los OR no ajustados indicaron un aumento en el riesgo de deterioro cognitivo o demencia en los adultos mayores con sobrecarga anticolinérgica (OR 1,47; IC del 95%: 1,09 a 1,96) y los OR ajustados indicaron igualmente un aumento en el riesgo de sobrecarga anticolinérgica, definida según la escala ACB (OR 2,63; IC del 95%: 1,09 a 6,29). El análisis exploratorio que combina los OR ajustados entre las escalas disponibles apoyó estos resultados (OR 2,16; IC del 95%: 1,38 a 3,38) y hubo evidencia de variabilidad en el riesgo según la intensidad de la carga anticolinérgica (1 en escala ACB): OR 2,18; IC del 95%: 1,11 a 4,29; 2 en escala ACB: OR 2,71; IC del 95%: 2,01 a 3,56; 3 en escala ACB: OR 3,27; IC del 95%: 1,41 a 7,61); sin embargo, la evaluación global de la certeza de la evidencia con el método GRADE fue baja. CONCLUSIONES DE LOS AUTORES: Existe evidencia de certeza baja de que los adultos mayores sin deterioro cognitivo que toman fármacos con efectos anticolinérgicos podrían tener un mayor riesgo de deterioro cognitivo o demencia.

Propensity score methods in real-world epidemiology: A practical guide for first-time users.

Real-world epidemiology gives us the unique opportunity to observe large numbers of people, and the actions and events that characterize their encounters with healthcare providers. However, the heterogeneity and sheer diversity of the population and healthcare systems makes it impossible for researchers to compare "like with like" when attempting to draw causal inferences about interventions and outcomes. The critical issue in epidemiological datasets relates to high risk of bias due to confounders that stem from baseline differences between groups. Propensity score (PS) techniques are statistical approaches that have been used to tackle potential imbalance in the comparison groups. The PS is the estimated probability (based on measured baseline covariates) that the patient receives a particular intervention. Patients that share similar PS will most likely have the same distributions of underlying covariates included in the PS. Implementation of PS methods may achieve better balance of covariates, but there is no consensus on the best way of capturing all relevant confounders for incorporation into the PS model. Should covariates be selected by clinical or epidemiological experts, or would data-driven algorithms (machine learning) offer more efficient and reliable methods of estimating PS and controlling for confounding? The PS can be incorporated into the analysis in different ways, each with its own strengths and limitations, and researchers must choose the best fit for their study objectives. PS methods are particularly advantageous in situations where there are large numbers of measured covariates but relatively few outcome events captured in healthcare administrative databases.

Effectiveness of 80% vs 30-35% fraction of inspired oxygen in patients undergoing surgery: an updated systematic review and meta-analysis.

BACKGROUND: In 2016, the World Health Organization (WHO) strongly recommended the use of a high fraction of inspired oxygen (FiO2) in adult patients undergoing general anaesthesia to reduce the risk of surgical site infection (SSI). Since then, further trials have been published, trials included previously have come under scrutiny, and one article was retracted. We updated the systematic review on which the recommendation was based. METHODS: We performed a systematic literature search from January 1990 to April 2018 for RCTs comparing the effect of high (80%) vs standard (30-35%) FiO2 on the incidence of SSI. Studies retracted or under investigation were excluded. A random effects model was used for meta-analyses; the sources of heterogeneity were explored using meta-regression. RESULTS: Of 21 RCTs included, six were newly identified since the publication of the WHO guideline review; 17 could be included in the final analyses. Overall, no evidence for a reduction of SSI after the use of high FiO2 was found [relative risk (RR): 0.89; 95% confidence interval (CI): 0.73-1.07]. There was evidence that high FiO2 was beneficial in intubated patients [RR: 0.80 (95% CI: 0.64-0.99)], but not in non-intubated patients [RR: 1.20 (95% CI: 0.91-1.58); test of interaction; P=0.048]. CONCLUSIONS: The WHO updated analyses did not show definite beneficial effect of the use of high perioperative FiO2, overall, but there was evidence of effect of reducing the SSI risk in surgical patients under general anaesthesia with tracheal intubation. However, the evidence for this beneficial effect has become weaker and the strength of the recommendation needs to be reconsidered.

Safety of 80% vs 30-35% fraction of inspired oxygen in patients undergoing surgery: a systematic review and meta-analysis.

BACKGROUND: Evidence-based guidelines from the World Health Organization (WHO) have recommended a high (80%) fraction of inspired oxygen (FiO2) to reduce surgical site infection in adult surgical patients undergoing general anaesthesia with tracheal intubation. However, there is ongoing debate over the safety of high FiO2. We performed a systematic review to define the relative risk of clinically relevant adverse events (AE) associated with high FiO2. METHODS: We reviewed potentially relevant articles from the WHO review supporting the recommendation, including an updated (July 2018) search of EMBASE and PubMed for randomised and non-randomised controlled studies reporting AE in surgical patients receiving 80% FiO2 compared with 30-35% FiO2. We assessed study quality and performed meta-analyses of risk ratios (RR) comparing 80% FiO2 against 30-35% for major complications, mortality, and intensive care admission. RESULTS: We included 17 moderate-good quality trials and two non-randomised studies with serious-critical risk of bias. No evidence of harm with high FiO2 was found for major AE in the meta-analysis of randomised trials: atelectasis RR 0.91 [95% confidence interval (CI) 0.59-1.42); cardiovascular events RR 0.90 (95% CI 0.32-2.54); intensive care admission RR 0.93 (95% CI 0.7-1.12); and death during the trial RR 0.49 (95% CI 0.17-1.37). One non-randomised study reported that high FiO2 was associated with major respiratory AE [RR 1.99 (95% CI 1.72-2.31)]. CONCLUSIONS: No definite signal of harm with 80% FiO2 in adult surgical patients undergoing general anaesthesia was demonstrated and there is little evidence on safety-related issues to discourage its use in this population.

Hepatic late adverse effects after antineoplastic treatment for childhood cancer.

BACKGROUND: Survival rates have greatly improved as a result of more effective treatments for childhood cancer. Unfortunately, the improved prognosis has been accompanied by the occurrence of late, treatment-related complications. Liver complications are common during and soon after treatment for childhood cancer. However, among long-term childhood cancer survivors, the risk of hepatic late adverse effects is largely unknown. To make informed decisions about future cancer treatment and follow-up policies, it is important to know the risk of, and associated risk factors for, hepatic late adverse effects. This review is an update of a previously published Cochrane review. OBJECTIVES: To evaluate all the existing evidence on the association between antineoplastic treatment (that is, chemotherapy, radiotherapy involving the liver, surgery involving the liver and BMT) for childhood cancer and hepatic late adverse effects. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2018, Issue 1), MEDLINE (1966 to January 2018) and Embase (1980 to January 2018). In addition, we searched reference lists of relevant articles and scanned the conference proceedings of the International Society of Paediatric Oncology (SIOP) (from 2005 to 2017) and American Society of Pediatric Hematology/Oncology (ASPHO) (from 2013 to 2018) electronically. SELECTION CRITERIA: All studies, except case reports, case series, and studies including fewer than 10 patients that examined the association between antineoplastic treatment for childhood cancer (aged 18 years or less at diagnosis) and hepatic late adverse effects (one year or more after the end of treatment). DATA COLLECTION AND ANALYSIS: Two review authors independently performed the study selection and 'risk of bias' assessment. The 'risk of bias' assessment was based on earlier checklists for observational studies. For the original version of the review, two review authors independently performed data extraction. For the update of the review, the data extraction was performed by one reviewer and checked by another reviewer. MAIN RESULTS: Thirteen new studies were identified for the update of this review. In total, we included 33 cohort studies including 7876 participants investigating hepatic late adverse effects after antineoplastic treatment (especially chemotherapy and radiotherapy) for different types of childhood cancer, both haematological and solid malignancies. All studies had methodological limitations. The prevalence of hepatic late adverse effects, all defined in a biochemical way, varied widely, between 0% and 84.2%. Selecting studies where the outcome of hepatic late adverse effects was well-defined as alanine aminotransferase (ALT) above the upper limit of normal, indicating cellular liver injury, resulted in eight studies. In this subgroup, the prevalence of hepatic late adverse effects ranged from 5.8% to 52.8%, with median follow-up durations varying from three to 23 years since cancer diagnosis in studies that reported the median follow-up duration. A more stringent selection process using the outcome definition of ALT as above twice the upper limit of normal, resulted in five studies, with a prevalence ranging from 0.9% to 44.8%. One study investigated biliary tract injury, defined as gamma-glutamyltransferase (γGT) above the upper limit of normal and above twice the upper limit of normal and reported a prevalence of 5.3% and 0.9%, respectively. Three studies investigated disturbance in biliary function, defined as bilirubin above the upper limit of normal and reported prevalences ranging from 0% to 8.7%. Two studies showed that treatment with radiotherapy involving the liver (especially after a high percentage of the liver irradiated), higher BMI, and longer follow-up time or older age at evaluation increased the risk of cellular liver injury in multivariable analyses. In addition, there was some suggestion that busulfan, thioguanine, hepatic surgery, chronic viral hepatitis C, metabolic syndrome, use of statins, non-Hispanic white ethnicity, and higher alcohol intake (> 14 units per week) increase the risk of cellular liver injury in multivariable analyses. Chronic viral hepatitis was shown to increase the risk of cellular liver injury in six univariable analyses as well. Moreover, one study showed that treatment with radiotherapy involving the liver, higher BMI, higher alcohol intake (> 14 units per week), longer follow-up time, and older age at cancer diagnosis increased the risk of biliary tract injury in a multivariable analysis. AUTHORS' CONCLUSIONS: The prevalence of hepatic late adverse effects among studies with an adequate outcome definition varied considerably from 1% to 53%. Evidence suggests that radiotherapy involving the liver, higher BMI, chronic viral hepatitis and longer follow-up time or older age at follow-up increase the risk of hepatic late adverse effects. In addition, there may be a suggestion that busulfan, thioguanine, hepatic surgery, higher alcohol intake (>14 units per week), metabolic syndrome, use of statins, non-Hispanic white ethnicity, and older age at cancer diagnosis increase the risk of hepatic late adverse effects. High-quality studies are needed to evaluate the effects of different therapy doses, time trends, and associated risk factors after antineoplastic treatment for childhood cancer.

The development of search filters for adverse effects of medical devices in medline and embase.

BACKGROUND: Objectively derived search filters for adverse drug effects and complications in surgery have been developed but not for medical device adverse effects. OBJECTIVE: To develop and validate search filters to retrieve evidence on medical device adverse effects from ovid medline and embase. METHODS: We identified systematic reviews from Epistemonikos and the Health Technology Assessment (hta) database. Included studies within these reviews that reported on medical device adverse effects were randomly divided into three test sets and one validation set of records. Using word frequency analysis from one test set, we constructed a sensitivity maximising search strategy. This strategy was refined using two other test sets, then validated. RESULTS: From 186 systematic reviews which met our inclusion criteria, 1984 unique included studies were available from medline and 1986 from embase. Generic adverse effects searches in medline and embase achieved 84% and 83% sensitivity. Recall was improved to over 90%, however, when specific adverse effects terms were added. CONCLUSION: We have derived and validated novel search filters that retrieve over 80% of records with medical device adverse effects data in medline and embase. The addition of specific adverse effects terms is required to achieve higher levels of sensitivity.

The development of search filters for adverse effects of surgical interventions in medline and Embase.

BACKGROUND: Search filter development for adverse effects has tended to focus on retrieving studies of drug interventions. However, a different approach is required for surgical interventions. OBJECTIVE: To develop and validate search filters for medline and Embase for the adverse effects of surgical interventions. METHODS: Systematic reviews of surgical interventions where the primary focus was to evaluate adverse effect(s) were sought. The included studies within these reviews were divided randomly into a development set, evaluation set and validation set. Using word frequency analysis we constructed a sensitivity maximising search strategy and this was tested in the evaluation and validation set. RESULTS: Three hundred and fifty eight papers were included from 19 surgical intervention reviews. Three hundred and fifty two papers were available on medline and 348 were available on Embase. Generic adverse effects search strategies in medline and Embase could achieve approximately 90% relative recall. Recall could be further improved with the addition of specific adverse effects terms to the search strategies. CONCLUSION: We have derived and validated a novel search filter that has reasonable performance for identifying adverse effects of surgical interventions in medline and Embase. However, we appreciate the limitations of our methods, and recommend further research on larger sample sizes and prospective systematic reviews.

Important factors in predicting mortality outcome from stroke: findings from the Anglia Stroke Clinical Network Evaluation Study.

Background: Although variation in stroke service provision and outcomes have been previously investigated, it is less well known what service characteristics are associated with reduced short- and medium-term mortality. Methods: Data from a prospective multicentre study (2009­12) in eight acute regional NHS trusts with a catchment population of about 2.6 million were used to examine the prognostic value of patient-related factors and service characteristics on stroke mortality outcome at 7, 30 and 365 days post stroke, and time to death within 1 year. Results: A total of 2,388 acute stroke patients (mean (standard deviation) 76.9 (12.7) years; 47.3% men, 87% ischaemic stroke) were included in the study. Among patients characteristics examined increasing age, haemorrhagic stroke, total anterior circulation stroke type, higher prestroke frailty, history of hypertension and ischaemic heart disease and admission hyperglycaemia predicted 1-year mortality. Additional inclusion of stroke service characteristics controlling for patient and service level characteristics showed varying prognostic impact of service characteristics on stroke mortality over the disease course during first year after stroke at different time points. The most consistent finding was the benefit of higher nursing levels; an increase in one trained nurses per 10 beds was associated with reductions in 30-day mortality of 11­28% (P < 0.0001) and in 1-year mortality of 8­12% (P < 0.001). Conclusions: There appears to be consistent and robust evidence of direct clinical benefit on mortality up to 1 year after acute stroke of higher numbers of trained nursing staff over and above that of other recognised mortality risk factors.

Methodological review: quality of randomized controlled trials in health literacy.

BACKGROUND: The growing move towards patient-centred care has led to substantial research into improving the health literacy skills of patients and members of the public. Hence, there is a pressing need to assess the methodology used in contemporary randomized controlled trials (RCTs) of interventions directed at health literacy, in particular the quality (risk of bias), and the types of outcomes reported. METHODS: We conducted a systematic database search for RCTs involving interventions directed at health literacy in adults, published from 2009 to 2014. The Cochrane Risk of Bias tool was used to assess quality of RCT implementation. We also checked the sample size calculation for primary outcomes. Reported evidence of efficacy (statistical significance) was extracted for intervention outcomes in any of three domains of effect: knowledge, behaviour, health status. Demographics of intervention participants were also extracted, including socioeconomic status. RESULTS: We found areas of methodological strength (good randomization and allocation concealment), but areas of weakness regarding blinding of participants, people delivering the intervention and outcomes assessors. Substantial attrition (losses by monitoring time point) was seen in a third of RCTs, potentially leading to insufficient power to obtain precise estimates of intervention effect on primary outcomes. Most RCTs showed that the health literacy interventions had some beneficial effect on knowledge outcomes, but this was typically for less than 3 months after intervention end. There were far fewer reports of significant improvements in substantive patient-oriented outcomes, such as beneficial effects on behavioural change or health (clinical) status. Most RCTs featured participants from vulnerable populations. CONCLUSIONS: Our evaluation shows that health literacy trial design, conduct and reporting could be considerably improved, particularly by reducing attrition and obtaining longer follow-up. More meaningful RCTs would also result if health literacy trials were designed with public and patient involvement to focus on clinically important patient-oriented outcomes, rather than just knowledge, behaviour or skills in isolation.

Bone mineral density and incidence of stroke: European prospective investigation into cancer-norfolk population-based study, systematic review, and meta-analysis.

BACKGROUND AND PURPOSE: The prospective link between osteoporosis and future risk of stroke requires evidence from large-scale population-based long-term studies. METHODS: Calcaneum broadband ultrasound attenuation was measured in the Norfolk cohort of the European Prospective Investigation into Cancer-Norfolk between 1997 and 2000. Incident strokes were ascertained by hospital record linkage and death certificates in March 2009 and December 2011, respectively. A search of MEDLINE and EMBASE was performed to evaluate the relationship between bone mineral density and incident stroke. After data extraction of relevant studies, pooled risk of stroke was estimated using meta-analysis. RESULTS: In 14 290 participants (mean follow-up of 9.3 years; total person-years 132 574), there were 599 incident strokes. Participants in the lowest 10% of the calcaneum broadband ultrasound attenuation distribution had an increased stroke risk (hazard ratio 1.41; 95% confidence intervals, 1.02-1.94) compared with those in the top 30% of the distribution after adjustments. A decrease of ~1 standard deviation in broadband ultrasound attenuation (20 db/MHz) was associated with a 17% increase in relative risk of stroke (95% confidence intervals, 5%-30%). Meta-analysis of 4 studies (25 760 participants, 1237 cases of stroke) found that for every decrease in 1 standard deviation in bone mineral density, there was an increased risk of incident stroke among women (pooled relative risk 1.22; 95% confidence intervals, 1.09-1.37; I2=0%, 3 studies) but not in men (pooled relative risk 1.05; 95% confidence intervals, 0.94-1.17; I(2)=0%, 2 studies). CONCLUSIONS: Bone mineral density predicts total stroke risk. The evidence is stronger in women with regard to the continuous relationship.

New Adverse Drug Reaction Signals from 2017 to 2021-Genuine Alerts or False Alarms?

Spontaneous adverse events reporting systems are used internationally to flag new or unexpected adverse drug reactions (ADRs). Disproportionality analysis is a recognised technique, but false alarms may arise. We aimed to determine whether these new ADR signals had subsequently been followed-up with detailed hypothesis-testing studies. We searched PubMed to identify published studies (years 2017-2021) where the authors reported findings of new ADR signals from disproportionality analyses. We used PubMed and forward citation tracking (Google Scholar) to identify any subsequent confirmatory studies of these ADR signals. We screened 414 titles and abstracts and checked the full-text articles of 57 studies. We found signals for 56 suspected new ADRs from 24 drugs. Google Scholar showed that the ADR studies had been cited a median of seven times (range 0-61). However, none of the suspected new ADRs had undergone detailed evaluation in the citing literature. Similarly, our PubMed search did not find any confirmation studies for the 56 suspected new ADRs. Although many suspected new ADR signals have been identified through disproportionality analysis, most signals have not been further verified as being either genuine ADRs or false alarms. Researchers must focus on follow-up studies for these new signals.

Functional polymorphisms of folate metabolism and response to chemotherapy for colorectal cancer, a systematic review and meta-analysis.

OBJECTIVES: Many primary studies have considered the association of polymorphisms of folate metabolism and response to 5-fluorouracil (5-FU) and capecitabine in patients with colorectal cancer. The conclusions from these studies have been conflicting and few have considered large cohorts of patients. Therefore, we have completed a systematic review and meta-analyses to summarize some of the findings to date. We conducted searches for any studies that had addressed the prognostic value of genotype analysis of thymidylate synthetase (TYMS), Methylenetetrahydrofolate reductase (MTHFR) and dihydrofolate reductase (DHFR). METHODS: We collected data on the study designs, and completed meta-analyses to pool congruent data about treatment effect. A narrative summary is presented for 39 studies that describe three TYMS genotypes and two MTHFR genotypes associated with response to 5-FU-based chemotherapy. RESULTS: Data were synthesized from up to 2402 patients for the most commonly studied markers TYMS 5' UTR repeat polymorphism (rs45445694) and MTHFR 677 C>T (rs1801133). We found that the TYMS genotype associated with the lowest protein expression (2R/2R) was significantly associated with improved clinical benefit; the pooled risk ratio was relative risk=1.36 [1.11, 1.65]; P=0.003. Moreover, the same trend was observed for adverse effects; the pooled risk ratio was 2.04 [1.42, 2.95]; P=0.0001. CONCLUSION: There is a small but statistically significant association between treatment effect (both intended effects and adverse events) and a TYMS genotype associated with low protein expression; however, the effect size is small and therefore indicates limited clinical utility.

Risk of Clostridium difficile infection with acid suppressing drugs and antibiotics: meta-analysis.

OBJECTIVES: Several studies have raised concern regarding the possible association between proton-pump inhibitors (PPIs) and Clostridium difficile infection (CDI). We aimed to perform a systematic review of incident and recurrent CDI in PPI users, and to evaluate the relative impact of concurrent antibiotic use, or switching acid suppression to histamine-2-receptor antagonists (H2RAs). METHODS: We searched MEDLINE and EMBASE from inception to December 2011 for controlled observational studies that reported on the risk of CDI with and without PPI use. We performed random effects meta-analysis and assessed statistical heterogeneity using the I(2) statistic. RESULTS: We included 42 observational studies (30 case-control, 12 cohort) totalling 313,000 participants overall. Pooled analysis of 39 studies showed a statistically significant association between PPI use and risk of developing CDI, odds ratio (OR) 1.74 (95% confidence interval (CI) 1.47-2.85, P<0.001, I(2)=85%) compared with non-users. A pooled analysis of three studies showed a significant associated risk of recurrent CDI associated with PPIs, OR 2.51 (95% CI 1.16-5.44, P=0.005, I(2)=78%). Subgroup analysis failed to fully clarify the source of the substantial statistical heterogeneity. Adjusted indirect comparison demonstrated that use of H2RAs as an alternative carried a lower-risk OR 0.71 (95% CI 0.53-0.97) compared with PPIs. Conversely, concomitant use of PPI and antibiotics conferred a greater-risk OR 1.96 (95% CI 1.03-3.70) above that of PPIs alone. For PPI and antibiotics, the Rothman's synergy index was 1.36 and attributable proportion of risk from interaction 0.19, indicating an increased risk from interaction beyond the effects of each drug alone. CONCLUSIONS: Despite the substantial statistical and clinical heterogeneity, our findings indicate a probable association between PPI use and incident and recurrent CDI. This risk is further increased by concomitant use of antibiotics and PPI, whereas H2RAs may be less harmful.

Statins and associated risk of pneumonia: a systematic review and meta-analysis of observational studies.

PURPOSE: Statins have potential anti-inflammatory effects, but the association between statin use and lower incidence of pneumonia is unclear. We have therefore performed a systematic review on the risk of pneumonia in statin users versus non-users. METHODS: MEDLINE and EMBASE were searched in December 2010 for controlled observational studies that reported on the risk of pneumonia in statin users. We performed a random effects meta-analysis and assessed heterogeneity using the I² statistic. RESULTS: A total of 451 citations were screened, and ultimately nine studies (4 case-control, 4 retrospective cohort, 1 prospective cohort) with more than 3 million participants were included in the meta-analysis. Pooled analysis of seven studies that reported unadjusted data failed to show a significantly reduced risk of pneumonia [odds ratio (OR) 0.94, 95% confidence interval (CI) 0.84-1.06, p = 0.33, I² = 79%] in statin users as compared to non-users. However, a significant reduction in the likelihood of pneumonia associated with statin use (n = 8 studies, OR 0.85, 95% CI 0.75-0.97, p = 0.02, I² = 81%) was found in the meta-analysis of adjusted data. Both analyses were limited by substantial statistical heterogeneity. Sensitivity analysis failed to fully clarify the source of heterogeneity, but cohort studies seemed to be less heterogenous (n = 5 studies, OR 0.92, 95% CI 0.84-1.01, I² = 43%). CONCLUSION: Our findings indicate that the purported benefit of statins in preventing pneumonia is inconsistent, and of low magnitude, with upper bounds of the confidence interval being close to null. In view of the substantial statistical and clinical heterogeneity in the dataset, there is no convincing evidence to support the therapeutic application of statins for reducing the risk of pneumonia.

Bisphosphonates and atrial fibrillation: systematic review and meta-analysis.

BACKGROUND: Bisphosphonates are widely used in osteoporosis, but there have been concerns about a potential link between bisphosphonate therapy and atrial fibrillation. OBJECTIVE: We aimed to systematically evaluate the risk of atrial fibrillation associated with bisphosphonate use. METHODS: We searched MEDLINE, regulatory authority websites, pharmaceutical company trial registers and product information sheets for randomized controlled trials (RCTs) and controlled observational studies published in English through to May 2008. We selected RCTs of bisphosphonates versus placebo for osteoporosis or fractures, with at least 3 months of follow-up, and data on atrial fibrillation. For the observational studies, we included case-control or cohort studies that evaluated the risk of atrial fibrillation in patients exposed to bisphosphonates compared with non-exposure. Data on atrial fibrillation as the primary outcome, and stroke and cardiovascular mortality as secondary outcomes, were extracted. DATA SYNTHESIS/RESULTS: We calculated pooled odds ratio (OR) using random effects meta-analysis, and estimated statistical heterogeneity with the I2 statistic. Bisphosphonate exposure was significantly associated with risk of atrial fibrillation serious adverse events in a meta-analysis of four trial datasets (OR 1.47; 95% CI 1.01, 2.14; p = 0.04; I2 = 46%). However, meta-analysis of all atrial fibrillation events (serious and non-serious) from the same datasets yielded a pooled OR of 1.14 (95% CI 0.96, 1.36; p = 0.15; I2 = 0%). We identified two case-control studies, one of which found an association between bisphosphonate exposure (ever users) and atrial fibrillation (adjusted OR 1.86; 95% CI 1.09, 3.15) while the other showed no association (adjusted OR 0.99; 95% CI 0.90, 1.10). Both studies failed to demonstrate a significant association in 'current' users. We did not find a significant increase in the risk of stroke (three trial datasets; OR 1.00; 95% CI 0.82, 1.22; p = 0.99; I2 = 0%) or cardiovascular mortality (three trial datasets; OR 0.86; 95% CI 0.66, 1.13; p = 0.28; I2 = 31%). CONCLUSION: While there are some data linking bisphosphonates to serious atrial fibrillation, heterogeneity of the existing evidence, as well as paucity of information on some of the agents, precludes any definitive conclusions on the exact nature of the risk.