Clinical and economic implications of therapeutic switching of Angiotensin Receptor Blockers to Angiotensin-Converting Enzyme Inhibitors: A population-based study

Objective To evaluate the clinical and cost impact of switching Angiotensin Receptor Blockers (ARBs) to Angiotensin-Converting Enzyme Inhibitors (ACEIs) in patients with hypertension. Methods This study used the UK Clinical Practice Research Datalink, linking with the Hospital Episode Statistics (April-2006 to March-2012). Adults with hypertension (n=470) were followed from the first ARBs prescription date to the switching date (pre-switching period); then from the switching date to the date when study ended, patient left the dataset or died (post-switching period). Patients were divided into ACEIs-combined (n=369) and ACEIs-monotherapy (n=101) groups by whether additional antihypertensive drugs were prescribed with ACEIs in the post-switching period. Proportion of Days Covered (PDC), clinical outcomes and costs were compared between the pre- and post-switching periods using a multilevel regression. Results Overall, in the post-switching period, there was a significant increase in the proportion of non-adherence (PDC<80%) (OR: 2.4; 95%CI: 1.6, 3.7), but a significant reduction in mean SBP (mean difference [MD]: -2.3; 95CI: -3.4, -1.2mmHg) and mean DBP (MD: -1.9; 95%CI: -2.6, -1.2mmHg). However, these results were only observed in the ACEIs-combined group. There was no post-switching significant difference in either the incidence of individual or composite HT-related complications (OR: 0.9; 95%CI: 0.4, 2.0). There was a significant reduction in the overall annual medical cost per patient by £329 (95%CI: -534, -205). Conclusions Switching of ARBs to ACEIs monotherapy appeared to be clinically-effective and a cost-saving strategy. The observed changes in the ACEIs-combined group are assumed to be related to factors other than the ARBs switching.