Atenolol as initial antihypertensive therapy: an observational study comparing first-line agents.

OBJECTIVE: The role of atenolol in the management of patients with hypertension is currently under scrutiny. Our aim was to evaluate the real-world consequences of recent clinical trial findings. METHODS: We conducted a retrospective, cohort study using linked administrative data from the province of Saskatchewan, Canada. Eligible subjects were first-ever users of antihypertensive medications between 1 January 1994 and 31 December 2003 and were grouped into four cohorts: atenolol, angiotensin-converting enzyme inhibitors (ACEI), thiazide diuretics, or calcium antagonists. Patients remained eligible during monotherapy only. RESULTS: We identified 19 249 eligible individuals (mean age 60.6 years) who were followed for a mean of 2.3 years (SD 2.0). The rate of myocardial infarction, unstable angina, stroke, or death occurred in similar frequencies among all cohorts: atenolol (2.3%), ACEI (3.6%), thiazide diuretics (2.9%), and calcium antagonists (3.9%). After adjustment for potential confounders, atenolol therapy was not associated with higher event rates than the other first-line agents, with hazard ratios ranging between 1.03 [95% confidence intervals (CI) 0.72-1.46] and 1.24 (95% CI 0.91-1.68) for all cohorts compared with atenolol. Similar results were observed upon stratifying the sample into subjects above and below 60 years of age. CONCLUSION: The low event rates for all cohorts suggest that atenolol has not been associated with a significant burden of cardiovascular morbidity or mortality in its traditional role for uncomplicated hypertension. Further study is needed to identify the specific types of patients that should avoid atenolol as an antihypertensive agent.

Cardiovascular morbidity associated with nonadherence to statin therapy.

STUDY OBJECTIVE: To measure the extent of cardiovascular morbidity associated with nonadherence to 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor (statin) therapy. DESIGN: Retrospective cohort study. DATA SOURCE: Linked administrative health databases in Saskatchewan, Canada. PATIENTS: A total of 1221 patients aged 30-70 years who received a new prescription for a statin drug between 1994 and 2001, within 1 year of their first cardiovascular event (i.e., myocardial infarction, unstable angina, ischemic stroke, percutaneous transluminal coronary angioplasty [PTCA], or coronary artery bypass graft [CABG]). MEASUREMENTS AND MAIN RESULTS: Adherence was measured by the fill frequency (number of prescriptions filled during the observation period divided by months of observation). Patients with a fill frequency of 80% or greater were classified as adherent (661 patients); those with a fill frequency of 60% or less were classified as nonadherent (395 patients). The remaining 165 patients who had adherence rates of 61-79% were excluded from the analysis. The primary end point included a composite of myocardial infarction, unstable angina, PTCA, CABG, and death. Among 1056 patients, adherence was not associated with a reduction of the primary end point. However, patients in the adherent group were half as likely to experience a subsequent myocardial infarction as the patients in the nonadherent group (hazard ratio [HR] 0.45, 95% confidence interval [CI] 0.20-0.99, p=0.047). In patients younger than 65 years (both adherent and not), the associated reduction in myocardial infarction was even more profound (HR 0.14, 95% CI 0.04-0.46, p=0.001) and was accompanied by a trend for a lower frequency of unstable angina (HR 0.37, 95% CI 0.13-1.03, p=0.06). In patients 65 years or older (301 patients), adherence was not associated with significant changes in cardiovascular end points. CONCLUSION: A detectable excess of cardiovascular morbidity appears to be associated with nonadherence to statin therapy. Our analysis suggests that many occurrences of myocardial infarction could be prevented with improvements in adherence. Larger studies are necessary to determine the association between adherence and other cardiovascular end points.

Adherence to statins, beta-blockers and angiotensin-converting enzyme inhibitors following a first cardiovascular event: a retrospective cohort study.

BACKGROUND: Population studies of statin adherence are generally restricted to one to two years of follow-up and do not analyze adherence to other drugs. OBJECTIVES: To report long-term adherence rates for statins, angiotensin-converting enzyme (ACE) inhibitors and beta-blockers in patients who recently experienced a first cardiovascular event. METHODS: Linked administrative databases in the province of Saskatchewan were used in this retrospective cohort study. Eligible patients received a new statin prescription within one year of their first cardiovascular event between 1994 and 2001. Adherence to statins, beta-blockers and ACE inhibitors was assessed from the first statin prescription to a subsequent cardiovascular event. RESULTS: Of 1221 eligible patients, the proportion of patients adherent to statin medications dropped to 60.3% at one year and 48.8% at five years. The decline in the proportion of adherent patients was most notable during the first two years (100% to 53.7%). Several factors were associated with statin adherence, including age (P = 0.012), number of physician service days (P = 0.037), chronic disease score (P = 0.032), beta-blocker adherence (P < 0.001) and ACE inhibitor adherence (P < 0.001). Adherence to beta-blockers and ACE inhibitors was very similar to adherence to statin medications at each year of follow-up. CONCLUSIONS: Patients who exhibit optimal adherence over one to two years after their initial cardiovascular event generally remain adherent over subsequent years. Also, adherence to beta-blockers and ACE inhibitors is significantly associated with statin adherence in a subset of patients; however, overall adherence to all three drugs was similarly poor.