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.