Higher continuity of statin use associated with decreased all-cause mortality

In a retrospective cohort study published in the Archives of Internal Medicine, higher continuity of statin treatment was associated with a lower risk of all-cause mortality among patients with or without coronary heart disease (CHD). This association was consistent after adjustments for age, sex, chronic conditions, use of antihypertensive and diuretic agents, and number of hospitalizations.

In this study, data were obtained from databases at Macabi Healthcare Services, a 1.7 million-enrollee health maintenance organization in Israel. Patients eligible for inclusion were those who were continuously enrolled in the plan since 1995 or earlier. New statin users were defined as patients aged ≥18 years who received ≥1 dispensed prescription for a statin between January 1, 1998, and December 31, 2006. The date of the first dispensed prescription was the index date. Risk of mortality was assessed in 2 patient cohorts: the primary prevention cohort, defined as patients with no indication of CHD or other cardiovascular disease; and the secondary prevention cohort, defined as patients with coronary artery disease (CAD).

A total of 229,918 patients were assessed in this study, including 136,052 patients in the primary prevention cohort and 93,866 patients in the secondary prevention cohort. Patients in the secondary prevention cohort were more likely to use high-efficacy statins as initial therapy, have a higher number of physician visits, and have lower median low-density lipoprotein (LDL) cholesterol levels. Among all patients, simvastatin was the statin most commonly used. A total of 4,259 patients in the primary prevention cohort and 8,906 patients in the secondary prevention cohort died during follow-up (mean follow-up, 4 years for primary prevention cohort; 5 years for secondary prevention cohort).

The investigators also performed sensitivity analyses to assess the potential for bias. After excluding patients with <1 year of follow-up after the index date, the investigators demonstrated that patients in the primary prevention cohort with PDC ≥90% had an adjusted HR of 0.42 (95% CI, 0.37–0.47); patients in the secondary prevention cohort with PDC ≥90% had an adjusted HR of 0.39 (95% CI, 0.36–0.42).

The authors pointed out that their analysis was limited by several factors, including its retrospective nature and lack of randomization for statin therapy. They also suggested that the lower mortality risk observed with higher statin PDC could be the result of unmeasured variables that are associated with a higher quality of care or more aggressive therapy. Additionally, information on statin use was derived from dispensing records, which may not necessarily translate into statin consumption.

Despite these limitations, the investigators concluded that "the observed benefits from statins were greater than expected from randomized clinical trials, emphasizing the importance of promoting statin therapy and increasing its continuation over time for both primary and secondary prevention."

SOURCE

Shalev V, Chodick G, Silber H, Kokia E, Jan J, Heymann AD. Continuation of statin treatment and all-cause mortality. Arch Intern Med. 2009;169:260–268.