Data collection process
Data were extracted independently
by one author (RJM) using a standard form. This included: author, year
of publication, class of diuretic(s) and dose used, protocol (including
presence of background therapy and whether placebo controlled), sample
size, average age, sex distribution, ethnicity (if available) and
prevalence of diabetes (if available). For the outcome measurements,
mean (± standard deviation/standard error) of values for BP and
aldosterone before and during diuretic (and before and during placebo
treatment in placebo-controlled studies) and the difference between
values on and before treatment. Where available, the difference in
renin, serum potassium and systolic blood pressure (SBP) were extracted.
If standard deviations were not reported these were calculated from
standard errors, P-values or from confidence intervals. The duration of
diuretic treatment at the time of measurement was also recorded. Where
only graphical reports of measurements were available, an estimation
from the graph was taken if it was judged to be accurate to within 10%.
Units of aldosterone were converted to pmol/L for analysis if other
units were used.