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Fixed-effect Model (fixed-effect + model)
Selected AbstractsSystematic review and meta-analysis of clinically relevant adverse events from HMG CoA reductase inhibitor trials worldwide from 1982 to present,PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 2 2007David L. McClure PhD Abstract Purpose Our objective was to determine the association of clinically relevant adverse events from a systematic review and meta-analysis of statin randomized controlled trials (RCT). Methods We performed the meta-analysis in the manner of a Cochrane Collaboration systematic review. Outcomes were discontinuances of therapy or muscle-related symptoms due to adverse events. We searched for articles from 1982 through June 2006 in MEDLINE and other databases. The main inclusion criteria were double blind, placebo controlled RCTs with a monotherapy intervention of any marketed statin and active surveillance of adverse events. We excluded studies of drug interactions, organ transplants, or exercise, or those not meeting all of the study quality criteria. The primary analysis was a statin formulation stratified fixed-effect model using Peto odds-ratios (POR). Secondary analyses explored the stability of the primary results. Results Over 86,000 study participants from 119 studies were included. Available statins were associated with a lower POR of discontinuance (overall: 0.88 [0.84, 0.93], largest effect with pravastatin: 0.79 [0.74, 0.84]), an elevated POR of rhabdomyolysis (1.59 [0.54, 4.70]) and myositis (2.56 [1.12, 5.85]), and null odds of myalgia (1.09 [0.97, 1.23]). Cerivastatin by comparison demonstrated larger PORs for discontinuances and muscle-related adverse events. Secondary analyses demonstrated the stability of the results. Conclusions Overall, discontinuation of statin therapy due to adverse events was no worse than placebo. The risks of muscle-related adverse events were in general agreement with the known risks of statins. Copyright © 2006 John Wiley & Sons, Ltd. [source] Use of tamoxifen in advanced-stage hepatocellular carcinoma,CANCER, Issue 7 2005A systematic review Abstract BACKGROUND Hepatocellular carcinoma (HCC) is the third most common cause of cancer mortality worldwide. Survival is poor for patients with advanced-stage HCC, and small trials of tamoxifen for patients with this disease have shown conflicting results. The authors conducted a systematic review of randomized clinical trials to compare the effect of a tamoxifen-containing arm with a nontamoxifen-containing arm in advanced HCC. METHODS Eligible trials were identified from the Cochrane Hepato-Biliary Group register and other databases. Studies were selected for inclusion and their methodologic quality assessed by three independent reviewers. Hazard ratios (HR) were derived for overall survival where possible. Metaanalysis was performed using a fixed-effect model. RESULTS The authors identified 10 randomized trials with a total of 1709 patients. Use of tamoxifen had no effect on median survival (HR, 1.05; 95% confidence interval, 0.94,1.16; P = 0.4) or tumor response rate. The findings were stable in sensitivity analyses and were not affected by publication bias or inclusion of low-quality studies or studies reported in abstract form only. Few adverse events or withdrawals were noted. CONCLUSIONS There was no support for the therapeutic use of tamoxifen in advanced HCC, nor for its use as a control arm in future clinical trials. Cancer 2005. © 2005 American Cancer Society. [source] Adjunctive Low Molecular Weight Heparin During Fibrinolytic Therapy in Acute ST-Segment Elevation Myocardial Infarction: A Meta-Analysis Of Randomized Control TrialsCLINICAL CARDIOLOGY, Issue 7 2009Sarabjeet Singh MD Background Recent data suggests that low molecular weight heparins (LMWHs) may be superior to unfractionated heparin (UFH) as an adjunct to fibrinolytic therapy in patients with acute ST-segment elevation myocardial infarction (STEMI). Hypothesis We evaluated cardiac outcomes and the risk of major bleeding with LMWHs vs UFH in the management of STEMI. Methods Seven randomized trials of patients with acute STEMI treated with fibrinolytic therapy and adjunctive LMWHs through the index hospitalization or weight-based UFH for at least 48 hours were identified. We analyzed both primary endpoints (death and nonfatal recurrent myocardial infarction through 30 days), and secondary endpoints (death, recurrent myocardial infarction, and major bleeding during index hospitalization at 7 days). Outcomes were computed using the Mantel-Haenszel fixed-effect model. A 2-sided alpha error of < 0.05 was considered significant. Results Compared to UFH, LMWH significantly reduced reinfarction (p < 0.001) during hospitalization at 7 days and the effect remained consistent at 30 d (p < 0.001). When analyzed for mortality at 7 days and 30 days follow-up, there were no statistically significant differences observed between the 2 groups. Additionally the LMWH group had higher risk of major bleeding (p < 0.001). Conclusions The present meta-analysis suggests in patients receiving fibrinolytic therapy for STEMI, LMWHs as an adjunctive therapy is superior to UFH in reducing reinfarction during hospitalization at 7 days and at 30 days. The mortality was not significant between the 2 groups during hospitalization at 7 days and at 30 days. However, UFH is superior to LMWHs in the reduction of major bleeding at 7 days index hospitalization. Copyright © 2009 Wiley Periodicals, Inc. [source] The Effect of State Medicaid Case-Mix Payment on Nursing Home Resident AcuityHEALTH SERVICES RESEARCH, Issue 4p1 2006Zhanlian Feng Objective. To examine the relationship between Medicaid case-mix payment and nursing home resident acuity. Data Sources. Longitudinal Minimum Data Set (MDS) resident assessments from 1999 to 2002 and Online Survey Certification and Reporting (OSCAR) data from 1996 to 2002, for all freestanding nursing homes in the 48 contiguous U.S. states. Study Design. We used a facility fixed-effects model to examine the effect of introducing state case-mix payment on changes in nursing home case-mix acuity. Facility acuity was measured by aggregating the nursing case-mix index (NCMI) from the MDS using the Resource Utilization Group (Version III) resident classification system, separately for new admits and long-stay residents, and by an OSCAR-derived index combining a range of activity of daily living dependencies and special treatment measures. Data Collection/Extraction Methods. We followed facilities over the study period to create a longitudinal data file based on the MDS and OSCAR, respectively, and linked facilities with longitudinal data on state case-mix payment policies for the same period. Principal Findings. Across three acuity measures and two data sources, we found that states shifting to case-mix payment increased nursing home acuity levels over the study period. Specifically, we observed a 2.5 percent increase in the average acuity of new admits and a 1.3 to 1.4 percent increase in the acuity of long-stay residents, following the introduction of case-mix payment. Conclusions. The adoption of case-mix payment increased access to care for higher acuity Medicaid residents. [source] Breastfeeding as obesity prevention in the United States: A sibling difference modelAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2010Molly W. Metzger In light of the growing prevalence of obesity in the United States, and the health risks associated with childhood obesity in particular, it is critical to identify avenues for obesity prevention. This study tests the hypothesis that breastfeeding serves as one protective factor against children's subsequent development of obesity. We used linear-, logistic-, and sibling fixed-effects regression models to evaluate the association between infant feeding history and body mass index (BMI) in late childhood or adolescence (9,19 years, mean = 14 years). Complete data were available for 976 participants (488 sibling pairs) in the 2002 Child Development Supplement of the Panel Study of Income Dynamics, a nationally representative survey of families in the United States. In sibling pairs in which only one sibling was breastfed, the breastfed sibling had an adolescent BMI that was 0.39 standard deviations lower than his or her sibling, controlling for child-specific factors that may have influenced parents' feeding decisions. This effect is equivalent to a difference of more than 13 pounds for a 14-year-old child of average height. Furthermore, fixed-effects logistic regressions predicting overweight and obese status showed that breastfed siblings were less likely to reach those BMI thresholds. We therefore conclude that breastfeeding in infancy may be an important protective factor against the development of obesity in the United States. The application of a sibling fixed-effects model provides stronger evidence of a causal relationship than prior research reporting similar patterns of association. Am. J. Hum. Biol. 2010. © 2009 Wiley-Liss, Inc. [source] Pricing to Market Behavior by Canadian and U.S. Agri-food Exporters: Evidence from Wheat, Pulse and ApplesCANADIAN JOURNAL OF AGRICULTURAL ECONOMICS, Issue 2 2003Richard Carew A fixed-effects model to control for time variation in marginal costs is employed to pinpoint evidence of price discriminatory behavior of Canadian and U.S. exporters of agri-food products. We test for evidence of pricing to market behavior and whether price discrimination or commodity/country characteristics may provide a plausible explanation. A distinguishing feature of our approach is to examine the time-series properties of the data by the conventional augmented Dickey-Fuller and recently developed panel unit root test. The panel data set employed in this paper consists of annual exchange rates and export prices for three agri-food products (wheat, pulse and apples) exported by Canada and the U.S. in foreign markets during 1980,98. Our fixed-effects model suggests that U.S. exporters are sensitive to exchange rate changes, while Canadian exporters in most cases raised price markups in response to a depreciated currency in overseas markets. The results highlight the differences in pricing policy that both countries employ to merchandise agri-food products in export markets. Les auteurs ont recouru à un modèle à effets fixes pour contrôler la fluctuation des coûts marginaux dans le temps et montrer que les exportateurs canadiens et américains de produits agroalimentaires se comportent différemment dans l'établissement des prix. Ils ont tenté de vérifier si ce comportement varie avec les cours en vigueur sur le marché et essayé d'établir s'il s'explique par une discrimination au niveau des prix ou par les paramètres propres au produit ou au pays. Une particularité de cette approche est qu'elle tient compte des propriétés historiques des données en recourant à la version augmentée du test classique de Dickey Fuller et au tout nouveau test de racine unitaire reposant sur les panels. Le jeu de données recueillies par panel dont les auteurs se sont servis comprend le taux du change annuel et le prix d'exportation de trois produits agroalimentaires (blé, légumineuses à graine et pommes) que le Canada et les États-Unis ont écoulés sur les marchés étrangers entre 1980 et 1998. Le modèle à effets fixes laisse croire que les exportateurs américains sont sensibles au taux du change alors que, dans la plupart des cas, leurs homologues canadiens majorent les prix davantage consécutivement à une dépréciation des devises à l'étranger. Les résultats font ressortir les divergences entre les politiques de fixation des prix qu'emploient les deux pays pour écouler leurs produits agroalimentaires sur les marchés étrangers. [source] | ||||||||||