Being on statin therapy did not significantly reduce atherosclerotic cardiovascular disease (ASCVD) risk in postmenopausal women newly diagnosed with type 2 diabetes, according to a new analysis of Women’s Health Initiative (WHI) data.
Women not on statins at the time of their diabetes diagnosis had a hazard ratio of 1.42 for ASCVD compared with women without diabetes (95% CI 1.28-1.58), according to a research team led by Yunsheng Ma, MD, PhD, of the University of Massachusetts Medical School in Worcester.
For women on statins when diagnosed, the increase in risk compared with nondiabetic women was only slightly smaller (HR 1.39, 95% CI 1.12-1.74). The risk difference between the two diabetic groups was not significant (P=0.89), Ma and colleagues reported in the European Journal of Epidemiology.
Ma and colleagues said they had thought that statin treatment might blunt the increased ASCVD risk associated with diabetes, but the study results did not bear that out.
“The major finding in this large, prospective observational study on community-dwelling postmenopausal women was that regardless of statin use, postmenopausal women with new-onset diabetes had a significantly increased risk of ASCVD,” Ma and colleagues wrote.
“Overall, statin use has benefit for ASCVD risk,” Ma said in an email to MedPage Today. “However, if we can reduce statin-related diabetes, the benefit will be increased. Therefore, we have to emphasize the importance of prevention, monitoring, and detection of diabetes in postmenopausal women including those on statin medication. Development of a new line of lipid-lowering medication without elevated blood glucose would be helpful as well.”
Ma and colleagues analyzed data on more than 120,000 WHI participants ages 50-79. Participants did not have cardiovascular disease or diabetes at baseline. Mean follow-up was 13.6 years.
Incident diabetes was self-reported by the women annually. Statin use was determined at enrollment and at regular yearly intervals throughout the study. The study’s primary endpoint was atherosclerotic cardiovascular events, which was self-reported annually and adjudicated by blinded physicians. Secondary endpoints included myocardial infarction, stroke, and cardiovascular death.
The investigators used incident diabetes and statin use as time-varying covariates in a Cox regression model analysis.
Results were similar when they analyzed myocardial infarction, stroke, and cardiovascular death as separate outcomes. For example, in the nonstatin-treated group, the hazard ratio for myocardial infarction was 1.38 versus nondiabetic participants (95% CI 1.17-1.62) compared with 1.52 (95% CI 1.12-2.07) in the statin-treated group (P=0.55 for comparison).
A chief limitation of the study was that baseline data on blood lipid levels and glucose measurements were incomplete, and that no data on these measurements were available during follow-up, so that they were not included in the adjusted analysis, Ma and colleagues noted. Self-reporting of incident diabetes and cardiovascular events was also a potential source of bias.
In addition, “when interpreting the present results, one should be mindful that our observational study analysis does not directly estimate the efficacy of statins on ASCVD risk in those with and without diabetes, for which the clinical trials are a superior source of information,” Ma and colleagues said.
Another important limitation is that the study results cannot be generalized to men, Ma told MedPage Today. “[O]ur results are applicable for postmenopausal women; study of a male population is needed,” he said.