Objective: The effect of compliance with antihypertensive medications on the risk of cardiovascular outcomes in a population without a known history of cardiovascular disease has been addressed by a large population-based prospective, cohort study carried out by linking Italian administrative databases.
Methods: The cohort of 242 594 patients aged 18 years or older, residents in the Italian Lombardy Region, who were newly treated for hypertension during 2000-2001, was followed from index prescription until 2007. During this period patients who experienced a hospitalization for coronary or cerebrovascular disease were identified (outcome). Exposure to antihypertensive drugs from index prescription until the date of hospitalization or censoring was assessed. Proportional hazards models were fitted to assess the association between persistence on and adherence with antihypertensive drug therapy and outcome. Data were adjusted for several covariates.
Results: During an average follow-up of 6 years, 12 016 members of the cohort experienced the outcome. Compared with patients who experienced at least one episode of treatment discontinuation, those who continued treatment had a 37% reduced risk of cardiovascular outcomes (95% confidence interval 34-40%). Compared with patients who had very low drug coverage (proportion of days covered ≤ 25%), those at intermediate (from 51 to 75%) and high coverage (>75%) had risk reductions of 20% (16-24%) and 25% (20-29%), respectively. Similar effects were observed when coronary and cerebrovascular events were considered separately.
Conclusions: In the real life setting, fulfillment compliance with antihypertensive medications is effective in the primary prevention of cardiovascular outcomes.