Comparative effectiveness and prescribing trends of modified release versus immediate release indapamide in patients with hypertension: cohort study.

Objective: To investigate the prescribing trends of indapamide, a thiazide-like diuretic, and the long term comparative effectiveness of modified release versus immediate release indapamide.

Design: Cohort study.

Setting: IQVIA Medical Research Data UK database, incorporating data from The Health Improvement Network database, 1 January 2005 to 31 December 2020.

Participants: Of 1 904 289 patients with hypertension, 86 388 started indapamide treatment during the study period. 30 021 patients received modified release and 56 367 immediate release indapamide.

Main outcome measures: Monthly prescribing trends of modified release and immediate release indapamide are described. A pragmatic trial was emulated to compare the five year risks of composite cardiovascular events (myocardial infarction and stroke) and death between modified release and immediate release indapamide. Intention-to-treat and per protocol effects of treatment were estimated with pooled logistic regression models. Confounding and selection bias were accounted for by multivariable adjustments and inverse probability weights.

Results: 1 38 414 patients who used indapamide were identified among 1 904 289 patients with hypertension. A greater increase was seen in the proportion of users of immediate release indapamide (from 0.43% in 2005 to 2.31% in 2020) than in users of modified release indapamide (from 0.71% to 0.79%). 86 388 patients (30 021 and 56 367 who started modified release and immediate release indapamide, respectively) were eligible for the trial emulation. In the intention-to-treat analysis, no difference was found in the risk of cardiovascular events (hazard ratio 0.99, 95% confidence interval (CI) 0.90 to 1.08) or death (hazard ratio 0.97, 0.92 to 1.02) between modified release and immediate release indapamide. In the per protocol analysis, a lower risk of cardiovascular events was found with modified release indapamide than with immediate release indapamide (risk difference -0.39%, 95% CI -0.71% to -0.06%; hazard ratio 0.81, 95% CI 0.68 to 0.98), which was mainly driven by myocardial infarction (risk difference -0.36%, 95% CI -0.64% to -0.08%; hazard ratio 0.80, 95% CI 0.64 to 1.01). Similar risks of death (hazard ratio 1.03, 95% CI 0.90 to 1.17) were found for the two formulations.

Conclusions: In patients treated with indapamide for hypertension, starting treatment with modified release or immediate release indapamide had similar risks for cardiovascular events or all cause mortality. In an exploratory secondary analysis, sustained treatment with modified release preparations was associated with a lower the risk of cardiovascular events but not all cause mortality compared with immediate release preparations. These findings need to be confirmed in prospective studies.