Effect of statins on the association between high temperature and all-cause mortality in a socioeconomically disadvantaged population: a cohort study

High temperature increases all-cause mortality. Thermoregulatory ability is impaired in persons with elevated serum cholesterol, but can be improved by the administration of statins, even in the short-term. We investigated whether the impact of high temperature (≥24 °C) on all-cause mortality among socioeconomically disadvantaged adults with a current or past indication for a statin is attenuated by current use of a statin with temperature dependence, by using claims data from five US Medicaid programs supplemented with Medicare claims for dual-enrollees and meteorological data from 1999–2010. We identified 3,508,948 persons (3,181,752 person-years) in a 1:1 propensity score-matched cohort. The incidence rate of all-cause mortality (deaths per 1,000 person-years) was 21.9 (95% confidence interval [CI]: 21.6 to 22.3) in current statin users and 30.1 (95% CI: 30.2 to 30.6) in former users. The adjusted odds ratios of mortality for current vs. former statin use were statistically significantly lower than 1.0, suggesting a protective effect of current statin use, on days with high temperature, with either daily average temperature or daily maximum temperature, and declined as daily average temperature increased from 29 °C and daily maximum temperature increased from 34 °C. These results were robust to the adjustment for daily relative humidity.