Compliance in primary prevention with statins and associations with cardiovascular risk and death in a low-risk diabetes population

Background Contemporary data exploring cardiovascular risk associated with primary prevention statin treatment according to compliance, in a low-risk diabetes population are limited. Purpose To investigate whether primary prevention with statins and high adherence to statins reduce the associated risk of cardiovascular events or death in a low-risk diabetes population. Methods By use of Danish nationwide registers, we included 59,985 patients with newly diagnosed diabetes aged 40–79 years between 1 January 2005 until 31 June 2010 with no atherosclerotic cardiovascular disease, heart failure or chronic kidney failure prior to 18 months following diabetes diagnosis (index). Individuals were considered treated with statins if they were in treatment at diabetes diagnosis or initiated treatment within the first 6 months following diabetes diagnosis. Among individuals who were treated within the first 6 months, we calculated the proportion of the days covered (PDC) of statins within one year prior to index. We standardized 5-year risks of the combined end-point of myocardial infarction, ischemic stroke or all-cause mortality according to age at index, sex, atrial fibrillation, chronic obstructive pulmonary disease, cancer, ethnicity, year at index, highest attained educational level and claimed prescriptions of antidiabetic, antihypertensive, non-statin lipid-lowering drugs and anticoagulant drugs. Reported were standardized 5-year risk differences of the composite outcome between untreated vs. treated, including PDC, by sex and age-group. Results Following 6 months from the diagnosis of diabetes, 38,029 (63%) individuals were treated with statins, and among individuals treated with statins 23,894 (63%) individuals had a PDC-level of ≥80%. Any use of statins was associated with a lower standardized 5-year risk of the composite outcome (not covered: 15.1% 95% confidence intervals [CI] 14.7–16.0; covered 11.0% [CI 10.7–11.4]), corresponding to a risk difference of 4.1% [CI 3.5–4.6]. The standardized 5-year risks differed by sex, but the risk reductions were similar between men (4.3% [CI 3.5–5.0]) and women (3.9% [CI 3.1–4.7]), and the standardized risk reduction increased with advancing age-group (age 40–49 1.1% [0.2–1.9], 50–59 2.4% [1.5–3.3], 60–69 4.2% [3.2–5.2], 70–79 8.3% [6.7–9.9]. A statin PDC-level of <80% was associated with an increased standardized risk difference (reference PDC≥80%; PDC=60–80% 1.6% [CI 0.7–2.5]; PDC=40–60% 2.1% [CI 0.9–3.3], PDC=20–40% 4.1% [CI 2.8–5.5], PDC<20% 3.2% [CI 2.0–4.5]). Conclusions In 18-month surviving low-risk patients with diabetes, use of statins was associated with a lower 5-year risk of cardiovascular events or death, but a high adherence was important to maintain this effect. The reduced risk associated with statins was similar in men and women, and the magnitude of associated risk reduction increased with advancing age. Standardized 5-year risk differences Funding Acknowledgement Type of funding source: Foundation. Main funding source(s): Danish Heart Foundation