Quantitative data synthesis and statistical analysis
Meta-analysis was conducted using Comprehensive Meta-Analysis Software
Version 3 (Biostat, Englewood, New Jersey) [14]. Net changes in PA,
renin, potassium and systolic blood pressure were obtained as the
difference from baseline after treatment with either diuretic or
placebo. If there was no standard error of the mean change stated, it
was estimated from the p-value, number of observations and size of the
change. A random-effects model was used to compensate for between-study
heterogeneity in terms of demographic inconsistencies and different
diuretic doses [15] with calculation of the standardised mean
difference in PA and its 95% confidence interval (CI). Raw mean
differences were calculated for plasma potassium, and SBP and
standardised differences for PRA. Statistical heterogeneity was assessed
using Cochran’s Q test [16]. P < 0.05 was
considered statistically significant and all tests were 2-tailed.