The fading of reported effectiveness. A meta-analysis of randomised controlled trials.

ABSTRACT:

Background

The "real" effect size of a medical therapy is constant over time. In contrast, the effect size reported in randomised controlled trials (RCTs) may change over time because the sum of all kinds of bias influencing the reported effectiveness is not necessarily constant. As this would affect the validity of meta-analyses, we tested the hypothesis that the reported effect size decreases over time. Furthermore, we tested three hypotheses that would explain a possible change.

Methods

Because of well established outcome measures, the lipid-lowering drugs Pravastatin and Atorvastatin (serum low-density lipoprotein cholesterol, LDL-C) and the anti-glaucoma drugs Timolol and Latanoprost (intraocular pressure, IOP) were chosen for this investigation. Studies were identified

SUBMITTER: Gehr BT 

PROVIDER: S-EPMC1479361 | biostudies-literature | 2006 May

REPOSITORIES: biostudies-literature