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.


OBJECTIVE
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.
Blackburn
David F
DF
College of Pharmacy and Nutrition, University of Saskatchewan, Saskatoon, Canada. d.blackburn@usask.ca
Dobson
Roy T
RT
Blackburn
James L
JL
Wilson
Thomas W
TW
Stang
Mary Rose
MR
Semchuk
William M
WM
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000367:Age Factors; D000789:Angina, Unstable / Q000188:drug therapy; D015906:Angioplasty, Balloon, Coronary; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000627:therapeutic use*; D015331:Cohort Studies; D001026:Coronary Artery Bypass; D019992:Databases as Topic; D011307:Drug Prescriptions / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000627:therapeutic use*; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000188:drug therapy; D010349:Patient Compliance / Q000706:statistics & numerical data*; D012189:Retrospective Studies; D012525:Saskatchewan; D012720:Severity of Illness Index; D013997:Time Factors
D000319:Adrenergic beta-Antagonists; D000806:Angiotensin-Converting Enzyme Inhibitors; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors