OBJECTIVE Shang's recently published meta-analysis on homeopathic remedies (Lancet) based its main conclusion on a subset of eight larger trials out of 21 high quality trials (out of 110 included trials). We performed a sensitivity analysis on various other meaningful trial subsets of all high quality trials. STUDY DESIGN Subsets were defined according to sample size, type of homeopathy, type...

BACKGROUND There are a variety of ways in which accuracy of clinical tests can be summarised in systematic reviews. Variation in reporting of summary measures has only been assessed in a small survey restricted to meta-analyses of screening studies found in a single database. Therefore, we performed this study to assess the measures of accuracy used for reporting results of primary studies as w...

OBJECTIVE To examine whether deviation from the standard intention to treat analysis has an influence on treatment effect estimates of randomised trials. DESIGN Meta-epidemiological study. DATA SOURCES Medline, via PubMed, searched between 2006 and 2010; 43 systematic reviews of interventions and 310 randomised trials were included. ELIGIBILITY CRITERIA FOR SELECTING STUDIES From each yea...

OBJECTIVES To determine whether exercise is more effective than usual care to reduce work disability in patients with non-acute non-specific low back pain, and if so, to explore which type of exercise is most effective. METHODS Systematic review and meta-analysis of randomized controlled trials investigating the effectiveness of exercise in non-acute non-specific low back pain, and reporting ...

One of the most frequently cited reasons for conducting a meta-analysis is the increase in statistical power that it affords a reviewer. This article demonstrates that fixed-effects meta-analysis increases statistical power by reducing the standard error of the weighted average effect size (T.) and, in so doing, shrinks the confidence interval around T.. Small confidence intervals make it more ...

BACKGROUND Genome-wide association studies identified novel breast cancer susceptibility variants that could be used to predict breast cancer in asymptomatic women. This review and modeling study aimed to investigate the current and potential predictive performance of genetic risk models. METHODS Genotypes and disease status were simulated for a population of 10,000 women. Genetic risk models...

BACKGROUND Prestigious journals select for publication studies that are considered most important and informative. We aimed to examine whether high-impact general (HIG) medical journals systematically demonstrate more favourable results for experimental interventions compared with the rest of the literature. METHODS We scrutinized systematic reviews of the Cochrane Database (Issue 4, 2009) an...

BACKGROUND Post-operative cognitive dysfunction (POCD) occurs frequently after major surgery. Hypertension is well-established as a risk factor for age-related cognitive impairment, but it is unclear whether or not it also increases the risk of POCD. OBJECTIVE To evaluate the role of hypertension in POCD risk in a systematic review and meta-analysis. METHOD PubMed, Ovid SP and the Cochrane ...

BACKGROUND Split-mouth randomized controlled trials (RCTs) are popular in oral health research. Meta-analyses frequently include trials of both split-mouth and parallel-arm designs to derive combined intervention effects. However, carry-over effects may induce bias in split- mouth RCTs. We aimed to assess whether intervention effect estimates differ between split- mouth and parallel-arm RCTs in...