[show abstract][hide abstract] ABSTRACT: Theory and simulation suggest that randomized controlled trials (RCTs) stopped early for benefit (truncated RCTs) systematically overestimate treatment effects for the outcome that precipitated early stopping.
To compare the treatment effect from truncated RCTs with that from meta-analyses of RCTs addressing the same question but not stopped early (nontruncated RCTs) and to explore factors associated with overestimates of effect.
Search of MEDLINE, EMBASE, Current Contents, and full-text journal content databases to identify truncated RCTs up to January 2007; search of MEDLINE, Cochrane Database of Systematic Reviews, and Database of Abstracts of Reviews of Effects to identify systematic reviews from which individual RCTs were extracted up to January 2008.
Selected studies were RCTs reported as having stopped early for benefit and matching nontruncated RCTs from systematic reviews. Independent reviewers with medical content expertise, working blinded to trial results, judged the eligibility of the nontruncated RCTs based on their similarity to the truncated RCTs.
Reviewers with methodological expertise conducted data extraction independently.
The analysis included 91 truncated RCTs asking 63 different questions and 424 matching nontruncated RCTs. The pooled ratio of relative risks in truncated RCTs vs matching nontruncated RCTs was 0.71 (95% confidence interval, 0.65-0.77). This difference was independent of the presence of a statistical stopping rule and the methodological quality of the studies as assessed by allocation concealment and blinding. Large differences in treatment effect size between truncated and nontruncated RCTs (ratio of relative risks <0.75) occurred with truncated RCTs having fewer than 500 events. In 39 of the 63 questions (62%), the pooled effects of the nontruncated RCTs failed to demonstrate significant benefit.
Truncated RCTs were associated with greater effect sizes than RCTs not stopped early. This difference was independent of the presence of statistical stopping rules and was greatest in smaller studies.
JAMA The Journal of the American Medical Association 03/2010; 303(12):1180-7. · 29.98 Impact Factor
[show abstract][hide abstract] ABSTRACT: To evaluate whether paediatric randomized clinical trials (RCTs) adopt recent guidance on Data Monitoring Committees (DMCs), interim analysis and early termination.
We reviewed paediatric RCTs that reported on DMCs, interim analysis or early termination, published in eight general medical and paediatric journals (2005-2007). We searched full-text databases for eligible trials and recorded predefined parameters on each item. Reported activities were compared with current scientific guidance.
A total of 110 of 648 paediatric trials (17%) reported on DMC, interim analysis or early stopping. Various approaches for convening a DMC were identified; information on DMC composition and independence was limited. Strict predefined statistical stopping 'rules' were reported in 10 of 23 trials, and interim analyses were more frequently performed on efficacy than on safety outcomes (39/45 vs 27/45). No adjustment for repeated testing was reported in 11 of 33 trials reporting monitoring methods and in 7 of 17 early terminated trials. Validity of results from early stopped trials was threatened by small sample sizes. Incomplete reporting hampered a full analysis.
Few paediatric trials report on DMCs' roles, interim analysis or early stopping. Heterogeneous practices and apparent shortcomings jeopardize the validity of trial results. Easily accessible guidelines for the design, conduct and reporting of paediatric DMCs are needed.
[show abstract][hide abstract] ABSTRACT: Decisions about interim analysis and early stopping of clinical trials, as based on recommendations of Data Monitoring Committees (DMCs), have far reaching consequences for the scientific validity and clinical impact of a trial. Our aim was to evaluate the frequency and quality of the reporting on DMC composition and roles, interim analysis and early termination in pediatric trials.
We conducted a systematic review of randomized controlled clinical trials published from 2005 to 2007 in a sample of four general and four pediatric journals. We used full-text databases to identify trials which reported on DMCs, interim analysis or early termination, and included children or adolescents. Information was extracted on general trial characteristics, risk of bias, and a set of parameters regarding DMC composition and roles, interim analysis and early termination.
110 of the 648 pediatric trials in this sample (17%) reported on DMC or interim analysis or early stopping, and were included; 68 from general and 42 from pediatric journals. The presence of DMCs was reported in 89 of the 110 included trials (81%); 62 papers, including 46 of the 89 that reported on DMCs (52%), also presented information about interim analysis. No paper adequately reported all DMC parameters, and nine (15%) reported all interim analysis details. Of 32 trials which terminated early, 22 (69%) did not report predefined stopping guidelines and 15 (47%) did not provide information on statistical monitoring methods.
Reporting on DMC composition and roles, on interim analysis results and on early termination of pediatric trials is incomplete and heterogeneous. We propose a minimal set of reporting parameters that will allow the reader to assess the validity of trial results.
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