Relationship between adherence level to statins, clinical issues and health-care costs in real-life clinical setting

Statins have been shown to reduce the risk of major cardiovascular disease. We recognize that there is a major gap between the use of statins in actual practice and treatment guidelines for dyslipidemia. Low adherence to statins may have a significant impact on clinical issues and health-care costs. The objective is to evaluate the impact of low adherence to statins on clinical issues and direct health-care costs.

A cohort of 55,134 patients newly treated with statins was reconstructed from the Régie de l'Assurance Maladie du Québec and Med-Echo databases. Subjects included were aged between 45 and 85, initially free of cardiovascular disease, newly treated with statins between 1999 and 2002, and followed-up for a minimum of 3 years. Adherence to statins was measured in terms of the proportion of days' supply of medication dispensed over a defined period, and categorized as >or=80% or <80%. The adjusted odds ratio (OR) of cardiovascular events between the two adherence groups was estimated using a polytomous logistic analysis. The mean costs of direct health-care services were evaluated. A two-part model was applied for hospitalization costs.

The mean high adherence level to statins was around to 96% during follow-up; and this value was at 42% for the low adherence level. The patients with low adherence to statins were more likely to have coronary artery disease (OR 1.07; 95% confidence interval [CI], 1.01-1.13), cerebrovascular disease (OR 1.13; 95% CI 1.03-1.25), and chronic heart failure within 3-year period of follow-up (OR 1.13; 95% CI 1.01-1.26). Low adherence to statins was also associated with an increased risk of hospitalization by 4% (OR 1.04; 95% CI 1.01-1.09). Among patients who were hospitalized, low adherence to statins was significantly associated with increase of hospitalization costs by approximately $1060/patient for a 3-year period.

Low adherence to statins was correlated with a higher risk of cardiovascular disease, hospitalization rate, and hospitalization costs. An increased level of adherence to statins agents should provide a better health status for individuals and a net economic gain.