Discontinuation of antihypertensive drugs among newly diagnosed hypertensive patients in UK general practice

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Abstract
Objectives To evaluate antihypertensive drug discontinuation among newly diagnosed hypertensive patients. Methods This was a population-based cohort study using the UK General Practice Research Database (GPRD). Patients newly diagnosed with hypertension between 1991 and 2001 and subsequently treated with antihypertensive drugs were included. Overall antihypertensive drug discontinuation was evaluated from a patient's first-ever antihypertensive prescription. Class-specific discontinuations were evaluated from a patient's first-ever prescriptions of angiotensin-converting enzyme (ACE) inhibitors (ACE-I), alpha antagonists, angiotensin-2 antagonists (AIIA), β blockers, calcium-channel blockers (CCB), miscellaneous, potassium-sparing diuretics, and thiazides. Discontinuation occurred when no antihypertensive prescription was issued within 90 days following the most recent prescription expiration. Results The study population comprised 109 454 patients, with 223 228 antihypertensive drug-class episodes contributing to the class-specific analysis. Overall antihypertensive drug discontinuation was 20.3% [95% confidence interval (CI): 20.0, 20.5%] at 6 months and 28.5% (95% CI: 28.2, 28.7%) at 1 year, with a median time to discontinuation of 3.07 years. The median time to antihypertensive class discontinuation was longest for AIIAs (2.90 years) followed by ACE-I (2.24), CCB (1.86), β blockers (1.50), thiazides (1.50), alpha antagonists (1.35), potassium-sparing diuretics (0.40), and miscellaneous (0.39). One-year discontinuation ranged from 29.4% (95% CI: 28.0, 30.7) for AIIAs to 64.1% (95% CI: 62.1, 66.3) for potassium-sparing diuretics. Forty-four percent who discontinue their first-ever antihypertensive drug class failed to switch to a different drug class within 90 days of discontinuation. Conclusion It is important that general practitioners (GPs) monitor patients closely in the first year following antihypertensive drug initiation, due to the high early risk of discontinuation, and the low percentage of patients who switch to a different antihypertensive drug class after a drug-class discontinuation. AIIA, followed by ACE-I and CCB, had the lowest risk of discontinuation among antihypertensive drug classes.