OBJECTIVE: To investigate whether a single trial can provide sufficiently robust evidence to warrant clinical implementation of its results. Trial-specific factors, such as subject selection, study design, and execution strategy, have an impact on the outcome of trials. In multiple trials, they may lead to heterogeneity that can be taken into account in the (random effects) meta-analysis. Single trials lack this method of estimating the impact of such factors, and this affects the credibility of the results. STUDY DESIGN AND SETTING: To indicate how much the precision of the results of a single trial might be overestimated, we calculated the ratio of the widths of the confidence intervals when heterogeneity was taken into account and when it was not. RESULTS: The ratios of the widths of the confidence intervals with and without between-study variability were 1.15, 1.41, and 2.00, when the heterogeneity I(2) values were 0.25, 0.50, and 0.75, respectively. CONCLUSION: The results of a single trial should be interpreted with caution. When it is difficult to predict or determine how trial-specific factors influence the results, the best way to evaluate the performance of a treatment is to use multiple, possibly smaller, trials.
OBJECTIVE: To investigate whether a single trial can provide sufficiently robust evidence to warrant clinical implementation of its results. Trial-specific factors, such as subject selection, study design, and execution strategy, have an impact on the outcome of trials. In multiple trials, they may lead to heterogeneity that can be taken into account in the (random effects) meta-analysis. Single trials lack this method of estimating the impact of such factors, and this affects the credibility of the results. STUDY DESIGN AND SETTING: To indicate how much the precision of the results of a single trial might be overestimated, we calculated the ratio of the widths of the confidence intervals when heterogeneity was taken into account and when it was not. RESULTS: The ratios of the widths of the confidence intervals with and without between-study variability were 1.15, 1.41, and 2.00, when the heterogeneity I(2) values were 0.25, 0.50, and 0.75, respectively. CONCLUSION: The results of a single trial should be interpreted with caution. When it is difficult to predict or determine how trial-specific factors influence the results, the best way to evaluate the performance of a treatment is to use multiple, possibly smaller, trials.
Authors: Joseph N Liu; Michael E Steinhaus; Grant H Garcia; Brenda Chang; Kara Fields; David M Dines; Russell F Warren; Lawrence V Gulotta Journal: Knee Surg Sports Traumatol Arthrosc Date: 2017-04-13 Impact factor: 4.342
Authors: Gianni Virgili; Andrea A Conti; Lorenzo Moja; Gian Franco Gensini; Roberto Gusinu Journal: Intern Emerg Med Date: 2009-10 Impact factor: 3.397
Authors: Janus Christian Jakobsen; Jørn Wetterslev; Per Winkel; Theis Lange; Christian Gluud Journal: BMC Med Res Methodol Date: 2014-11-21 Impact factor: 4.615