Trends in co-prescribing of angiotensin converting enzyme inhibitors and angiotensin receptor blockers in Ireland

center dot Renin-angiotensin-aldosterone system inhibition confers cardio-renal protection and may be achieved by monotherapy with an angiotensin enzyme converting inhibitor (ACEI) or an angiotensin-II receptor blocker (ARB). center dot Dual ACEI and ARB therapy has been examined in major clinical trials with conflicting results. center dot The prescribing pattern of dual therapy in general primary care population is not known. WHAT THIS STUDY ADDS center dot An increase in the co-prescribing of ACEIs and ARBs was observed in the Irish primary care population. center dot Co-prescribing of ACEIs and ARBs in the primary care population did not appear to be influenced by results from major clinical trials. center dot ACEIs and ARBs were more likely to be co-prescribed in special cohorts of the population with diabetes, hypertension and heart failure. AIMS (i) To examine the trends in co-prescribing of angiotensin converting enzyme inhibitor (ACEI) and angiotensin-II receptor blocker (ARB) therapy and (ii) to examine the influence of major clinical trials (CALM, COOPERATE, VALIANT and ONTARGET) on co-prescribing. METHODS The Irish HSE-Primary Care Reimbursement Services database was used to identify patients >= 16 years old co-prescribed ACEIs and ARBs between January 2000 and April 2009 (n = 266 554 prescriptions). The rate of prescribing per 1000 general medical services (GMS) scheme population was calculated for each month. Patients with diabetes, hypertension, heart failure and ischaemic heart disease were also identified by prescribing of certain medications. A linear trend test was used to examine prescribing trends. Logistic regression was used to examine prescribing according to patient characteristics. The effects of the major trials on prescribing were examined using segmented regression analysis for 12 months pre- and post-trials. RESULTS There was a significant linear trend in overall ACEI and ARB co-prescribing over the study period (P < 0.001). Rate of co-prescribing in January 2000 and April 2009 was 0.16 and 5.72, per 1000 eligible population, respectively. Those 45-64 years old (OR = 2.88, 95% confidence interval (CI) 2.71, 3.06) and >= 65 years (OR = 2.52, 95% CI 2.36, 2.68) were more likely to receive dual therapy compared with those < 45 years old. Those with hypertension (OR = 8.85, 95% CI 8.45, 9.27), diabetes (OR = 4.10, 95% CI 3.97, 4.23) and heart failure (OR = 1.78, 95% CI 1.72, 1.84) were more likely to receive dual therapy compared with the general population. Significant increases in prescribing were observed only after the CALM (P = 0.03) and VALIANT (P = 0.007) trials. CONCLUSION Increased co-prescribing of ACEIs and ARBs was observed in Ireland during 2000-09. Prescribing patterns did not appear to be affected by results from major trials.