Original metric vs. standardized effect sizes for meta-analysis of clinical data

Abstract

This study compared the use of the original metric effect size with the standardized effect size for clinical data in meta-analysis. The example data set included 17 controlled clinical trials dealing with the effects of progressive resistance exercise on resting diastolic blood pressure in adults. Original metric effect size showed a decrease in resting diastolic blood pressure of -2.07 mm Hg (95% confidence interval, -3.60 to -0.54). From a clinical standpoint, this is considered a "small" effect. The standardized approach showed an average effect of -0.21, 95% CI= -0.39 to -0.02. This is also considered a "small" effect. When possible, use of the original metric is preferred because it can be more clinically meaningful and will enhance interpretation of blood pressure results for a wider range of readers. © 2001 by CHF, Inc.