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1.
BMC Med Res Methodol ; 22(1): 168, 2022 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-35681120

RESUMO

BACKGROUND: In binary logistic regression data are 'separable' if there exists a linear combination of explanatory variables which perfectly predicts the observed outcome, leading to non-existence of some of the maximum likelihood coefficient estimates. A popular solution to obtain finite estimates even with separable data is Firth's logistic regression (FL), which was originally proposed to reduce the bias in coefficient estimates. The question of convergence becomes more involved when analyzing clustered data as frequently encountered in clinical research, e.g. data collected in several study centers or when individuals contribute multiple observations, using marginal logistic regression models fitted by generalized estimating equations (GEE). From our experience we suspect that separable data are a sufficient, but not a necessary condition for non-convergence of GEE. Thus, we expect that generalizations of approaches that can handle separable uncorrelated data may reduce but not fully remove the non-convergence issues of GEE. METHODS: We investigate one recently proposed and two new extensions of FL to GEE. With 'penalized GEE' the GEE are treated as score equations, i.e. as derivatives of a log-likelihood set to zero, which are then modified as in FL. We introduce two approaches motivated by the equivalence of FL and maximum likelihood estimation with iteratively augmented data. Specifically, we consider fully iterated and single-step versions of this 'augmented GEE' approach. We compare the three approaches with respect to convergence behavior, practical applicability and performance using simulated data and a real data example. RESULTS: Our simulations indicate that all three extensions of FL to GEE substantially improve convergence compared to ordinary GEE, while showing a similar or even better performance in terms of accuracy of coefficient estimates and predictions. Penalized GEE often slightly outperforms the augmented GEE approaches, but this comes at the cost of a higher burden of implementation. CONCLUSIONS: When fitting marginal logistic regression models using GEE on sparse data we recommend to apply penalized GEE if one has access to a suitable software implementation and single-step augmented GEE otherwise.


Assuntos
Modelos Estatísticos , Viés , Simulação por Computador , Humanos , Funções Verossimilhança , Modelos Logísticos
2.
Ann Surg Oncol ; 29(2): 1061-1070, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34647202

RESUMO

INTRODUCTION: Recent data suggest that margins ≥2 mm after breast-conserving surgery may improve local control in invasive breast cancer (BC). By allowing large resection volumes, oncoplastic breast-conserving surgery (OBCII; Clough level II/Tübingen 5-6) may achieve better local control than conventional breast conserving surgery (BCS; Tübingen 1-2) or oncoplastic breast conservation with low resection volumes (OBCI; Clough level I/Tübingen 3-4). METHODS: Data from consecutive high-risk BC patients treated in 15 centers from the Oncoplastic Breast Consortium (OPBC) network, between January 2010 and December 2013, were retrospectively reviewed. RESULTS: A total of 3,177 women were included, 30% of whom were treated with OBC (OBCI n = 663; OBCII n = 297). The BCS/OBCI group had significantly smaller tumors and smaller resection margins compared with OBCII (pT1: 50% vs. 37%, p = 0.002; proportion with margin <1 mm: 17% vs. 6%, p < 0.001). There were significantly more re-excisions due to R1 ("ink on tumor") in the BCS/OBCI compared with the OBCII group (11% vs. 7%, p = 0.049). Univariate and multivariable regression analysis adjusted for tumor biology, tumor size, radiotherapy, and systemic treatment demonstrated no differences in local, regional, or distant recurrence-free or overall survival between the two groups. CONCLUSIONS: Large resection volumes in oncoplastic surgery increases the distance from cancer cells to the margin of the specimen and reduces reexcision rates significantly. With OBCII larger tumors are resected with similar local, regional and distant recurrence-free as well as overall survival rates as BCS/OBCI.


Assuntos
Neoplasias da Mama , Mamoplastia , Neoplasias da Mama/cirurgia , Feminino , Humanos , Mastectomia Segmentar , Estudos Retrospectivos , Resultado do Tratamento
5.
Stat Methods Med Res ; 31(2): 253-266, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34931909

RESUMO

Poisson regression can be challenging with sparse data, in particular with certain data constellations where maximum likelihood estimates of regression coefficients do not exist. This paper provides a comprehensive evaluation of methods that give finite regression coefficients when maximum likelihood estimates do not exist, including Firth's general approach to bias reduction, exact conditional Poisson regression, and a Bayesian estimator using weakly informative priors that can be obtained via data augmentation. Furthermore, we include in our evaluation a new proposal for a modification of Firth's approach, improving its performance for predictions without compromising its attractive bias-correcting properties for regression coefficients. We illustrate the issue of the nonexistence of maximum likelihood estimates with a dataset arising from the recent outbreak of COVID-19 and an example from implant dentistry. All methods are evaluated in a comprehensive simulation study under a variety of realistic scenarios, evaluating their performance for prediction and estimation. To conclude, while exact conditional Poisson regression may be confined to small data sets only, both the modification of Firth's approach and the Bayesian estimator are universally applicable solutions with attractive properties for prediction and estimation. While the Bayesian method needs specification of prior variances for the regression coefficients, the modified Firth approach does not require any user input.


Assuntos
COVID-19 , Teorema de Bayes , Viés , Humanos , Funções Verossimilhança , SARS-CoV-2
6.
BMC Med Res Methodol ; 21(1): 199, 2021 09 30.
Artigo em Inglês | MEDLINE | ID: mdl-34592945

RESUMO

BACKGROUND: For finite samples with binary outcomes penalized logistic regression such as ridge logistic regression has the potential of achieving smaller mean squared errors (MSE) of coefficients and predictions than maximum likelihood estimation. There is evidence, however, that ridge logistic regression can result in highly variable calibration slopes in small or sparse data situations. METHODS: In this paper, we elaborate this issue further by performing a comprehensive simulation study, investigating the performance of ridge logistic regression in terms of coefficients and predictions and comparing it to Firth's correction that has been shown to perform well in low-dimensional settings. In addition to tuned ridge regression where the penalty strength is estimated from the data by minimizing some measure of the out-of-sample prediction error or information criterion, we also considered ridge regression with pre-specified degree of shrinkage. We included 'oracle' models in the simulation study in which the complexity parameter was chosen based on the true event probabilities (prediction oracle) or regression coefficients (explanation oracle) to demonstrate the capability of ridge regression if truth was known. RESULTS: Performance of ridge regression strongly depends on the choice of complexity parameter. As shown in our simulation and illustrated by a data example, values optimized in small or sparse datasets are negatively correlated with optimal values and suffer from substantial variability which translates into large MSE of coefficients and large variability of calibration slopes. In contrast, in our simulations pre-specifying the degree of shrinkage prior to fitting led to accurate coefficients and predictions even in non-ideal settings such as encountered in the context of rare outcomes or sparse predictors. CONCLUSIONS: Applying tuned ridge regression in small or sparse datasets is problematic as it results in unstable coefficients and predictions. In contrast, determining the degree of shrinkage according to some meaningful prior assumptions about true effects has the potential to reduce bias and stabilize the estimates.


Assuntos
Modelos Logísticos , Viés , Simulação por Computador , Humanos , Probabilidade
7.
Int J Surg ; 94: 106095, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34517135

RESUMO

BACKGROUND: Within the last decade numerous attempts have been reported in order to expand the donor pool and alleviate organ shortage in the setting of liver transplantation. Aim of this blinded randomized controlled trial was to evaluate the effect of donor steroid pretreatment on outcomes after liver transplantation. METHODS: We performed an international, multi-center double-blinded randomized placebo controlled trial. Donors received 1000 mg methylprednisone or placebo before organ procurement. Primary endpoint were patient and graft survival. Secondary end points were rate of BPAR and liver functions trajectories after transplantation. Follow up was 10 years. RESULTS: There was no effect of steroid pretreatment vs. placebo on overall patient survival (50% vs. 46%, p = n.s.) as well as graft survival (47% vs. 51%, p= n.s.). Further donor steroid pretreatment did not alter the rate of biopsy proven acute rejections (34% steroid group vs. 36% placebo, p = n.s.). Evaluating short term and long term graft function, steroid pretreatment had minor effect on immediate liver function trajectories within the first 2 weeks after transplantation. This was not seen in long-term follow up. CONCLUSION: In conclusion we found no evidence that donor steroid pretreatment translates in improved outcomes after liver transplantation.


Assuntos
Rejeição de Enxerto , Transplante de Rim , Aloenxertos , Seguimentos , Rejeição de Enxerto/prevenção & controle , Sobrevivência de Enxerto , Humanos , Fígado , Esteroides , Doadores de Tecidos , Resultado do Tratamento
8.
Eur J Dermatol ; 31(1): 65-74, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33648926

RESUMO

BACKGROUND: Organ transplant recipients (OTR) are at marked increased risk of skin cancer and skin infections compared to the general population. OBJECTIVES: The purpose of this study was to acquire long-term incidence data on commonly occurring skin diseases in four different transplant groups. MATERIALS & METHODS: This retrospective single-centre cohort study included 621 OTR. By counting defined malignant, inflammatory, infectious or drug-related skin conditions per patient and visit, incidence rates (IR) for the different groups of OTR were calculated as cases per 1000-patient years and cumulative incidences of non-melanoma skin cancer (NMSC), respectively. RESULTS: Overall, 2,309 non-malignant skin conditions and 340 NMSC were registered. Skin infections were most common (51.4%), followed by inflammatory skin conditions (35.6%) and sun-induced skin damage (32.9%). Kidney transplant recipients (KTR) had a 4.7-fold (95% CI: 2.7-8.0; p < 0.0001), 2.6-fold (95% CI: 1.2-5.3; p = 0.0098) and 5.4-fold (95% CI: 2.8-10.3; - < 0.0001) higher IR for oral candidiasis, oral aphthosis and herpes simplex virus infections, respectively, compared to the other OTR. Pruritus was most commonly reported in liver transplant recipients (95% CI: 1.3-5.3; p = 0.0047). KTR and lung transplant recipients (LuTR) had a 10.7-fold (95% CI:3.6-43.2; p < 0.0001) higher IR of steroid induced acne. KTR had a 1.6-fold (95% CI: 1.1-2.3; p = 0.0096) higher IR of squamous cell carcinoma compared to the other groups. The incidence of basal cell carcinoma was 2.5-fold higher (95% CI: 1.7-3.6; p < 0.0001) in LuTR, compared to the other OTR. CONCLUSION: This study provides additional organ-specific incidence data on non-malignant skin diseases and skin cancer in OTR.


Assuntos
Transplante de Órgãos , Complicações Pós-Operatórias/epidemiologia , Dermatopatias/epidemiologia , Adulto , Idoso , Estudos de Coortes , Feminino , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Fatores de Tempo
9.
Artigo em Inglês | MEDLINE | ID: mdl-31766753

RESUMO

The parameters of logistic regression models are usually obtained by the method of maximum likelihood (ML). However, in analyses of small data sets or data sets with unbalanced outcomes or exposures, ML parameter estimates may not exist. This situation has been termed 'separation' as the two outcome groups are separated by the values of a covariate or a linear combination of covariates. To overcome the problem of non-existing ML parameter estimates, applying Firth's correction (FC) was proposed. In practice, however, a principal investigator might be advised to 'bring more data' in order to solve a separation issue. We illustrate the problem by means of examples from colorectal cancer screening and ornithology. It is unclear if such an increasing sample size (ISS) strategy that keeps sampling new observations until separation is removed improves estimation compared to applying FC to the original data set. We performed an extensive simulation study where the main focus was to estimate the cost-adjusted relative efficiency of ML combined with ISS compared to FC. FC yielded reasonably small root mean squared errors and proved to be the more efficient estimator. Given our findings, we propose not to adapt the sample size when separation is encountered but to use FC as the default method of analysis whenever the number of observations or outcome events is critically low.


Assuntos
Modelos Teóricos , Projetos de Pesquisa , Tamanho da Amostra , Simulação por Computador , Humanos , Funções Verossimilhança , Modelos Logísticos
10.
Eur Surg ; 50(5): 228-231, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30294345

RESUMO

Background: In primary hyperparathyroidism (pHPT), quick intraoperative parathyroid hormone monitoring (IOPTH) is performed to predict complete excision of hyperfunctioning tissue and therefore cure. In recent years, efforts have been made to make this prediction more accurate and to shorten the duration of the test, respectively, and therefore reduce waiting and total operating time. The aim of this study was to evaluate the practicability and safety of a time-reduced criterion (decline ≥ 35% after 5 min) in a large cohort of patients. Methods: In an 11-year period, all patients operated for pHPT were analyzed. After preoperative localization studies, hyperfunctioning parathyroid tissue was removed and IOPTH monitoring was performed. Intraoperatively, a decline of ≥50% from baseline 10 min after excision of the gland predicted cure. The performance of an interpretation model, using an earlier PTH level was analyzed retrospectively (decline ≥ 35% from baseline 5 min after excision). Differences in sensitivity, specificity, positive/negative predictive value and accuracy were calculated. Results: According to the inclusion criteria, 1018 patients were analyzed. IOPTH predicted cure in 854 patients (83.9%) 10 min after gland excision with a false positive decline in 13 patients (1.5%). Applying the modified criterion (≥35% decline within 5 min), 814 patients (80%) showed an appropriate decline (false positive in 18 [2.2%]). Overall, multiple gland disease would have been missed in 7 patients. McNemar's test showed a significantly lower sensitivity, specificity and accuracy applying the "35%" criterion. Conclusions: In an endemic goiter region, a criterion, demanding a ≥ 35% decline 5 min after excision can not be recommended for IOPTH monitoring in patients with pHPT.

11.
PLoS One ; 13(1): e0191386, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29351547

RESUMO

OBJECTIVE: To demonstrate that when investigating the relevance of continuity of care for patient outcomes, different definitions can lead to contradicting results. METHODS: We used claims data from the regional public health insurer of Lower Austria covering the period from 2008 to 2011. The study sample included subjects with repeated dispensings of anti-diabetic drugs. The continuity of care index was calculated firstly based on a patient's contacts with general practitioners (primary COCI) and secondly based on contacts at all medical disciplines (total COCI). The association of the two continuity of care measures with mortality was assessed in separate univariable and multivariable Cox regression models. RESULTS: Our study sample consisted of 51,717 patients with a median observation time of 3.65 years. The data showed that a high total COCI was associated with increased mortality, while there was no association between primary COCI and mortality. CONCLUSIONS: Measures of continuity of care are highly sensitive to the type of medical disciplines taken into account. The continuity of care index calculated from contacts at all medical disciplines might measure diversity rather than continuity of care.


Assuntos
Continuidade da Assistência ao Paciente , Diabetes Mellitus/mortalidade , Diabetes Mellitus/terapia , Idoso , Áustria/epidemiologia , Estudos de Coortes , Continuidade da Assistência ao Paciente/estatística & dados numéricos , Diabetes Mellitus/tratamento farmacológico , Feminino , Humanos , Hipoglicemiantes/uso terapêutico , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Modelos de Riscos Proporcionais , Estudos Retrospectivos
12.
Clin Endocrinol (Oxf) ; 88(1): 129-138, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28906021

RESUMO

OBJECTIVE: Little is known about the natural changes in parathyroid function after successful parathyroid surgery for primary hyperparathyroidism. The association of intact parathyroid hormone (iPTH) and calcium (Ca) with "temporary hypoparathyroidism" and "hungry bone syndrome" (HBS) was evaluated. DESIGN: Potential risk factors for temporary hypoparathyroidism and HBS were evaluated by taking blood samples before surgery, intra-operatively, at postoperative day (POD) 1, at POD 5 to 7, in postoperative week (POW) 8 and in postoperative month (POM) 6. PATIENTS: Of 425 patients, 43 (10.1%) had temporary hypoparathyroidism and 36 (8.5%) had HBS. MEASUREMENTS: The discriminative ability of iPTH and Ca on POD 1 for temporary hypoparathyroidism and HBS. RESULTS: Intact parathyroid hormone (IPTH) on POD 1 showed the highest discriminative ability for temporary hypoparathyroidism (C-index = 0.952), but not for HBS. IPTH was helpful in diagnosing HBS between POD 5 and 7 (C-index = 0.708). Extending the model by including Ca resulted in little improvement of the discriminative ability for temporary hypoparathyroidism (C-index = 0.964) and a decreased discriminative ability for HBS (C-index = 0.705). Normal parathyroid metabolism was documented in 139 (32.7%) patients on POD 1 and in 423 (99.5%) 6 months postoperatively, while 2 (0.5%) patients had persistent hyperparathyroidism, one diagnosed between POD 5 and 7 and another at POW 8. No patients suffered from permanent hypoparathyroidism. CONCLUSIONS: The necessity for Ca and vitamin D3 substitution cannot be predicted with certainty before POD 5 to 7 without serial laboratory measurements. Based on the results, a routine 8-week course of Ca and vitamin D3 treatment seems reasonable and its necessity should be evaluated in a follow-up study.


Assuntos
Hiperparatireoidismo Primário/metabolismo , Glândulas Paratireoides/metabolismo , Período Pós-Operatório , Adulto , Cálcio/sangue , Cálcio/uso terapêutico , Feminino , Humanos , Hiperparatireoidismo Primário/cirurgia , Hipoparatireoidismo , Masculino , Pessoa de Meia-Idade , Hormônio Paratireóideo/sangue , Fatores de Risco , Fatores de Tempo , Vitamina D/uso terapêutico
13.
Am J Epidemiol ; 187(4): 864-870, 2018 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-29020135

RESUMO

Separation is encountered in regression models with a discrete outcome (such as logistic regression) where the covariates perfectly predict the outcome. It is most frequent under the same conditions that lead to small-sample and sparse-data bias, such as presence of a rare outcome, rare exposures, highly correlated covariates, or covariates with strong effects. In theory, separation will produce infinite estimates for some coefficients. In practice, however, separation may be unnoticed or mishandled because of software limits in recognizing and handling the problem and in notifying the user. We discuss causes of separation in logistic regression and describe how common software packages deal with it. We then describe methods that remove separation, focusing on the same penalized-likelihood techniques used to address more general sparse-data problems. These methods improve accuracy, avoid software problems, and allow interpretation as Bayesian analyses with weakly informative priors. We discuss likelihood penalties, including some that can be implemented easily with any software package, and their relative advantages and disadvantages. We provide an illustration of ideas and methods using data from a case-control study of contraceptive practices and urinary tract infection.


Assuntos
Interpretação Estatística de Dados , Projetos de Pesquisa Epidemiológica , Modelos Logísticos , Humanos , Tamanho da Amostra
14.
Clin Cancer Res ; 23(24): 7621-7632, 2017 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-28972047

RESUMO

Purpose: Most high-grade serous ovarian cancer (HGSOC) patients develop recurrent disease after first-line treatment, frequently with fatal outcome. This work aims at studying the molecular biology of both primary and recurrent HGSOC.Experimental Design: Gene expression profiles of matched primary and recurrent fresh-frozen tumor tissues from 66 HGSOC patients were obtained by RNA sequencing. Clustering analyses and pairwise comparison of the profiles between matched samples and subsequent functional alignment were used for the identification of molecular characteristics of HGSOC.Results: Both primary and recurrent HGSOC samples presented predominant gene expression differences in their microenvironment, determined by a panel of genes covering all major pathways of immune activation together with a number of genes involved in the remodeling of extracellular matrix and adipose tissues. Stratifying tumor tissues into immune active and silent groups, we further discovered that although some recurrent tumors shared the same immune status as their primary counterparts, others switched the immune status, either from silent to active or active to silent. Interestingly, genes belonging to the B7-CD28 immune checkpoint family, known for their major role as negative regulators of the immune response, were overexpressed in the immune active tumors. Searching for potential tumor antigens, CEACAM21, a member of the carcinoembryonic antigen family, was found to be significantly overexpressed in immune active tissues in comparison with the silent ones.Conclusions: The results illustrate the complexity of the tumor microenvironment in HGSOC and reveal the molecular relationship between primary and recurrent tumors, which have multiple therapeutic implications. Clin Cancer Res; 23(24); 7621-32. ©2017 AACR.


Assuntos
Antígenos de Neoplasias/genética , Cistadenocarcinoma Seroso/genética , Neoplasias Ovarianas/genética , Microambiente Tumoral/genética , Adulto , Idoso , Antígenos de Neoplasias/imunologia , Linhagem Celular Tumoral , Cistadenocarcinoma Seroso/imunologia , Cistadenocarcinoma Seroso/patologia , Feminino , Regulação Neoplásica da Expressão Gênica , Humanos , Pessoa de Meia-Idade , Gradação de Tumores , Recidiva Local de Neoplasia/genética , Recidiva Local de Neoplasia/patologia , Neoplasias Ovarianas/imunologia , Neoplasias Ovarianas/patologia , Análise de Sequência de RNA , Microambiente Tumoral/imunologia
15.
Stud Health Technol Inform ; 236: 305-310, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28508811

RESUMO

BACKGROUND: Patient adherence is an important component of an efficient therapy. For diabetes patients it may contribute to controlled glucose values and reduction of adverse outcomes. OBJECTIVES: We aim to examine a potential association of Lower Austrian diabetes patients' adherence concerning their disease monitoring and mortality. METHODS: Using a retrospective cohort study design, claims data of 55,873 diabetes patients were examined for regular HbA1c lab tests that served as a proxy for monitoring related adherence. The cumulative incidence of mortality was estimated in the total study population and separately for different levels of adherence using the product-limit method. Mortality was compared between the different levels of adherence by the log-rank test. RESULTS: The cumulative incidence of mortality after one and two years was 4.2% and 8.7%. Patients with low adherence had a significantly higher risk of mortality than patients with high adherence (p < 0.001). Further results of a multivariable analysis will be presented at the conference. CONCLUSION: According to our preliminary univariate analysis, monitoring related adherence seems to be substantially beneficial for diabetes patients in Lower Austria.


Assuntos
Diabetes Mellitus Tipo 2/mortalidade , Adesão à Medicação , Monitorização Ambulatorial , Áustria , Diabetes Mellitus Tipo 2/tratamento farmacológico , Humanos , Estimativa de Kaplan-Meier , Cooperação do Paciente , Estudos Retrospectivos
16.
Clin Endocrinol (Oxf) ; 87(1): 97-102, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28383779

RESUMO

OBJECTIVE: Normal or elevated 24-hour urinary calcium (Ca) excretion is a diagnostic marker in primary hyperparathyroidism (PHPT). It is used to distinguish familial hypocalciuric hypercalcaemia (FHH) from PHPT by calculating the Ca/creatinine clearance ratio (CCCR). The variance of CCCR in patients with PHPT is considerable. The aim of this study was to analyse the parameters affecting CCCR in patients with PHPT. DESIGN: The data were collected prospectively. Patients with sporadic PHPT undergoing successful surgery were included in a retrospective analysis. PATIENTS: The analysis covered 381 patients with pre-operative workup 2 days before removal of a solitary parathyroid adenoma. MEASUREMENTS: The impact of serum Ca and 25-hydroxyvitamin D3 (25-OH D3) on CCCR. RESULTS: The coefficient of determination (R2 ) in the multivariable model for CCCR consisting of age, Ca, 25-OH D3, 1,25-dihydroxyvitamin D3 (1,25-(OH)2 D3), testosterone (separately for males and females), intact parathyroid hormone (iPTH) and osteocalcin was 25.8%. The only significant parameters in the multivariable analysis were 1,25-(OH)2 D3 and osteocalcin with a drop in R2 of 15.4% (P<.001) and 2.4% (P=.006), respectively. Bone mineral densities at the lumbar spine, distal radius and left femoral neck were not associated with CCCR (r=-.08, r=-.10 and r=-0.09). CONCLUSIONS: In multivariable analysis, 1,25-(OH)2 D3 and osteocalcin were the only factors correlating with CCCR. Vitamin D3 replacement may therefore impair the diagnostic value of CCCR and increase the importance of close monitoring of urinary Ca excretion during treatment.


Assuntos
Cálcio/urina , Hiperparatireoidismo Primário/diagnóstico , Hiperparatireoidismo Primário/urina , Idoso , Creatinina/urina , Diagnóstico Diferencial , Feminino , Humanos , Hipercalcemia/congênito , Hipercalcemia/diagnóstico , Masculino , Pessoa de Meia-Idade , Osteocalcina/sangue , Neoplasias das Paratireoides/cirurgia , Período Pré-Operatório , Estudos Retrospectivos , Vitamina D/análogos & derivados , Vitamina D/sangue
17.
Int J Cardiol ; 235: 61-66, 2017 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-28262344

RESUMO

BACKGROUND: The beneficial use of dual antiplatelet therapy (DAPT) with acetylsalicylic acid (ASA) and P2Y12 õinhibitors has been established for patients after acute coronary syndrome (ACS). However, the optimal duration of DAPT is under debate. The aim of the present study was to investigate the long-term utilization and clinical outcome of clopidogrel, prasugrel, and ticagrelor in patients with ACS from 2009 to 2014 in Austria. METHODS: We analysed data from 13 Austrian health insurance funds for the years 2009 to 2014, on 72,676 patients with a hospital discharge diagnosis of ACS. The primary end point was recurrence of ACS or death >30days after the index event. RESULTS: 32,830 subjects received a prescription of a P2Y12 inhibitor within 30days after the index ACS. 18,640 (56.8%) subjects were discharged with clopidogrel, 6683 (20.4%) with prasugrel, and 7507 (22.9%) with ticagrelor, respectively. Data from 32,174 patients with 4975 events during a median follow-up period of 24.9months were available for survival analysis. The cumulative incidence for recurrence of ACS or death at two years was 18.7% in patients receiving clopidogrel, and 8.7% and 12.0% in those receiving prasugrel or ticagrelor, respectively. CONCLUSION: Utilization of P2Y12 inhibitors in patients with ACS was consistent with guideline recommendations. Prasugrel and ticagrelor are increasingly used in ACS patients and associated with a lower number of recurrence of ACS or death compared to clopidogrel. However, clopidogrel was predominantly used in older patients with more co-morbidities.


Assuntos
Síndrome Coronariana Aguda , Adenosina/análogos & derivados , Aspirina/uso terapêutico , Cloridrato de Prasugrel/uso terapêutico , Ticlopidina/análogos & derivados , Síndrome Coronariana Aguda/diagnóstico , Síndrome Coronariana Aguda/tratamento farmacológico , Síndrome Coronariana Aguda/epidemiologia , Adenosina/uso terapêutico , Idoso , Áustria/epidemiologia , Clopidogrel , Quimioterapia Combinada/métodos , Quimioterapia Combinada/estatística & dados numéricos , Feminino , Hospitalização/estatística & dados numéricos , Humanos , Incidência , Masculino , Conduta do Tratamento Medicamentoso/organização & administração , Conduta do Tratamento Medicamentoso/estatística & dados numéricos , Alta do Paciente/estatística & dados numéricos , Inibidores da Agregação Plaquetária/uso terapêutico , Recidiva , Análise de Sobrevida , Ticagrelor , Ticlopidina/uso terapêutico
18.
Stat Med ; 36(14): 2302-2317, 2017 06 30.
Artigo em Inglês | MEDLINE | ID: mdl-28295456

RESUMO

Firth's logistic regression has become a standard approach for the analysis of binary outcomes with small samples. Whereas it reduces the bias in maximum likelihood estimates of coefficients, bias towards one-half is introduced in the predicted probabilities. The stronger the imbalance of the outcome, the more severe is the bias in the predicted probabilities. We propose two simple modifications of Firth's logistic regression resulting in unbiased predicted probabilities. The first corrects the predicted probabilities by a post hoc adjustment of the intercept. The other is based on an alternative formulation of Firth's penalization as an iterative data augmentation procedure. Our suggested modification consists in introducing an indicator variable that distinguishes between original and pseudo-observations in the augmented data. In a comprehensive simulation study, these approaches are compared with other attempts to improve predictions based on Firth's penalization and to other published penalization strategies intended for routine use. For instance, we consider a recently suggested compromise between maximum likelihood and Firth's logistic regression. Simulation results are scrutinized with regard to prediction and effect estimation. We find that both our suggested methods do not only give unbiased predicted probabilities but also improve the accuracy conditional on explanatory variables compared with Firth's penalization. While one method results in effect estimates identical to those of Firth's penalization, the other introduces some bias, but this is compensated by a decrease in the mean squared error. Finally, all methods considered are illustrated and compared for a study on arterial closure devices in minimally invasive cardiac surgery. Copyright © 2017 John Wiley & Sons, Ltd.


Assuntos
Modelos Logísticos , Viés , Bioestatística , Procedimentos Cirúrgicos Cardíacos/efeitos adversos , Procedimentos Cirúrgicos Cardíacos/instrumentação , Procedimentos Cirúrgicos Cardíacos/estatística & dados numéricos , Simulação por Computador , Humanos , Funções Verossimilhança , Procedimentos Cirúrgicos Minimamente Invasivos/efeitos adversos , Procedimentos Cirúrgicos Minimamente Invasivos/instrumentação , Procedimentos Cirúrgicos Minimamente Invasivos/estatística & dados numéricos , Modelos Estatísticos , Probabilidade , Tamanho da Amostra , Dispositivos de Oclusão Vascular/efeitos adversos , Dispositivos de Oclusão Vascular/estatística & dados numéricos
19.
Anesthesiology ; 125(1): 256-7, 2016 07.
Artigo em Inglês | MEDLINE | ID: mdl-27326501
20.
Anesthesiology ; 124(1): 150-8, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26517858

RESUMO

BACKGROUND: Among patients with chronic low back pain (CLBP), approximately 37% show signs of a neuropathic pain component (radicular pain). Treatment of this condition remains challenging. Therefore, the current study aimed to investigate the efficacy of duloxetine in the treatment of CLBP patients with neuropathic leg pain. METHODS: The study was conducted as a prospective, randomized, placebo-controlled, double-blind crossover trial. CLBP with a visual analog scale (VAS) score greater than 5 and a neuropathic component that was assessed clinically and by the painDETECT questionnaire (score > 12) were required for inclusion. Patients were randomly assigned to either duloxetine or placebo for 4 weeks followed by a 2-week washout period before they crossed over to the alternate phase that lasted another 4 weeks. Duloxetine was titrated up to 120 mg/day. The primary outcome parameter was mean VAS score during the last week of treatment in each phase (VAS(week4)). RESULTS: Of 41 patients, 21 patients completed both treatment phases. In the intention-to-treat analysis (n = 25), VAS(week4) was significantly lower in the duloxetine phase compared with placebo (4.1 ± 2.9 vs. 6.0 ± 2.7; P = 0.001), corresponding to an average pain reduction of 32%. The painDETECT score at the end of each treatment phase was significantly lower in the duloxetine phase compared with placebo (17.7 ± 5.7 vs. 21.3 ± 3.6 points; P = 0.0023). Adverse events were distributed equally between the duloxetine (65%) and placebo phases (62%) (P = 0.5). CONCLUSION: In this crossover study, duloxetine proved to be superior to placebo for the treatment of CLBP with a neuropathic leg pain.


Assuntos
Analgésicos/farmacologia , Cloridrato de Duloxetina/farmacologia , Dor Lombar/complicações , Dor Lombar/tratamento farmacológico , Neuralgia/complicações , Neuralgia/tratamento farmacológico , Doença Crônica , Estudos Cross-Over , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Resultado do Tratamento
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