BACKGROUND Different confounder adjustment strategies were used to estimate odds ratios (ORs) in case-control study, i.e. how many confounders original studies adjusted and what the variables are. This secondary data analysis is aimed to detect whether there are potential biases caused by difference of confounding factor adjustment strategies in case-control study, and whether such bias would i...

BACKGROUND In the absence of sufficient data directly comparing multiple treatments, indirect comparisons using network meta-analyses (NMAs) can provide useful information. Under current contrast-based (CB) methods for binary outcomes, the patient-centered measures including the treatment-specific event rates and risk differences (RDs) are not provided, which may create some unnecessary obstacl...

IMPORTANCE A persistent dilemma when performing meta-analyses is whether all available trials should be included in the meta-analysis. OBJECTIVES To compare treatment outcomes estimated by meta-analysis of all trials and several alternative analytic strategies: single most precise trial (ie, trial with the narrowest confidence interval), meta-analysis restricted to the 25% largest trials, lim...

For meta-analysis, substantial uncertainty remains about the most appropriate statistical methods for combining the results of separate trials. An important issue for meta-analysis is how to incorporate heterogeneity, defined as variation among the results of individual trials beyond that expected from chance, into summary estimates of treatment effect. Another consideration is which 'metric' t...

BACKGROUND Power and precision are greater in meta-analyses than individual study analyses. However, dichotomisation of continuous outcomes in certain studies poses a problem as estimates from primary studies can only be pooled if they have a common outcome. Meta-analyses may include pooled summaries of either or both the continuous and dichotomous forms, and potentially have a different combin...

Asymmetry in funnel plots may indicate publication bias in meta-analysis, but the shape of the plot in the absence of bias depends on the choice of axes. We evaluated standard error, precision (inverse of standard error), variance, inverse of variance, sample size and log sample size (vertical axis) and log odds ratio, log risk ratio and risk difference (horizontal axis). Standard error is like...

STUDY OBJECTIVE To quantify the increase in mailed questionnaire response attributable to a monetary incentive. DESIGN A systematic search for randomised controlled trials of monetary incentives and mailed questionnaire response was conducted. For each trial identified, logistic regression was used to estimate the odds ratio for response per 0.01 dollars incentive increase. Odds ratios were p...

BACKGROUND A diverse range of study designs (e.g. case-control or cohort) are used in the evaluation of adverse effects. We aimed to ascertain whether the risk estimates from meta-analyses of case-control studies differ from that of other study designs. METHODS Searches were carried out in 10 databases in addition to reference checking, contacting experts, and handsearching key journals and c...

Introduction. Falls are frequent in older adults and may have serious consequences but awareness of fall-risk is often low. A questionnaire might raise awareness of fall-risk; therefore we set out to construct and test such a questionnaire. Methods. Fall-risk factors and their odds ratios were extracted from meta-analyses and a questionnaire was devised to cover these risk factors. A formula to...