Association of Treatment for Hyperlipidemia with Decreased Total Mortality in Japanese Individuals: the Yamagata (Takahata) Study

Aim: To evaluate the effects of treatment for hyperlipidemia on total mortality, we examined the association with adjustments for multiple factors, including those related to general health, such as blood hemoglobin and serum levels of albumin, adiponectin, brain natriuretic peptide, and lipids, using a prospective cohort study of a general Japanese population. Methods: The population-based, longitudinal Takahata study enrolled 3,291 Japanese individuals (1515 male, 1776 female; age: 62.5 +/- 10.3 years) between 2004 and 2006. The incidence and causes of death were annually monitored until January 10, 2012 (median follow-up period: 2,655 days). Results: During the follow-up period, there were 169 deaths. The Cox proportional hazard regression model analysis used to adjust for factors related to general health condition, cardiovascular disease risks, and serum lipid levels showed a significant association between treatment for hyperlipidemia and decreased total mortality compared with no treatment for hyperlipidemia [hazard ratio (HR): 0.24; 95% confidence interval (CI): 0.08-0.69) and subjects without hyperlipidemia (HR: 0.34; 95% CI: 0.12-0.96). The Cox proportional hazard regression model analysis with adjustments for factors related to general health conditions showed a significantly lower total mortality in subjects without hyperlipidemia than that in subjects with untreated hyperlipidemia (HR: 0.70; 95% CI: 0.50-0.99). Conclusions: Not only antihyperlipidemic drugs used but also selection bias and non-evaluated factors, such as socio-economic status, educational level, health literacy, and daily nutrition, affected the results. Subjects taking treatment for hyperlipidemia were found to have reduced total mortality, which was independent of serum lipid levels.