(P-529) Treatment Trajectory of Antihypertensive Drugs in UK Primary Care Practices

Background: Patients with hypertension initiating antihypertensive drugs often fail on their first-line treatment and require additional treatments. To date, no studies have described the treatment trajectory of these patients in the real-world setting of clinical practice.

Objectives: To describe the treatment trajectory of antihypertensive drug users over a 32-year period in the UK.

Methods: We used the UK Clinical Practice Research Datalink to identify patients with hypertension initiating a first-line antihypertensive drug (thiazide diuretics, ACE inhibitors, ARBs, CCBs, beta-blockers, and other drugs [i.e., non-thiazide diuretics, alpha-blockers]) between 1988 and 2019. Two cohorts were assembled, one before and one after 2007; corresponding to the date of major changes to treatment guidelines. In both cohorts, patients were followed from their initial first-line drug to subsequent treatment changes, defined by either a switch or add-on of a new antihypertensive class. At each treatment line, we documented the new antihypertensive drug class and the median number of days from the previous treatment line.

Results: The pre-2007 cohort included 287,084 patients. The common first-line drugs were thiazide diuretics (38.0%), beta-blockers (22.8%), and ACE inhibitors (19.5%). Among first-line thiazide diuretic users, ACE inhibitors and beta-blockers were the most common second-line drugs switched to or added-on (31.0% and 30.8%, respectively), with a median duration from first- to second-line treatment of 203 days and 82 days, respectively. Among first-line beta-blocker users, thiazide diuretics were the most common second-line treatment (31.0%), with a median duration from first- to second-line treatment of 175 days. The post-2007 cohort included 270,412 patients. The most common first-line drugs were ACE inhibitors (41.1%) and CCBs (31.7%); few received thiazide diuretics (9.5%) or ARBs (2.0%). Among first-line ACE inhibitor and ARB users, CCBs were the most common second-line drugs (43.7% and 42.6%, respectively), with a median duration from first- to second-line treatment of 169 days and 167 days, respectively. Alternatively, among first-line CCB users, ACE inhibitors were the most common second-line treatment (57.2%), with a median duration from first- to second-line treatment of 95 days.

Conclusions: In this large population-based study, thiazide diuretics and beta-blockers were the most common first-line antihypertensive drugs before 2007. In contrast, ACE inhibitors and CCBs were the most common first-line drugs after 2007. These treatment patterns should be considered when designing studies assessing the effectiveness and safety of antihypertensive drugs.