Periodic Limb Movements in Sleep is Associated with Increased Mortality

OBJECTIVE: To elucidate the association between periodic limb movements in sleep (PLMS) and mortality. METHODS: Nocturnal polysomnographic recordings of 1,344 subjects obtained from 1995 to 2008 were reviewed. The subjects were divided into four groups based on PLMS and insomnia: reference group (PLMS≤5), insomnia group (PLMS≤5 with insomnia symptoms), 5<PLMS≤15 group, and the PLMS>15 group. We searched each subject's Identification Number in the death records from the Statistics of Korea, the national bureau of statistics, to determine deaths in the cohort that occurred prior to December, 2013. Cox-proportional hazard regression and Kaplan-Meier survival curve analyses were used to compare mortality among the four groups. RESULTS: Hazard ratios (HRs) in the 5<PLMS≤15 and PLMS>15 groups were significantly higher than that in the reference group before adjusting for age and gender [HR, 3.37; 95% confidence interval (CI), 1.73–6.55; p<0.001; HR, 5.77; 95% CI, 3.24–10.29; p<0.001]. Only the PLMS>15 group had a higher mortality rate than that in the reference group after adjusting for age, gender, and sleep efficiency (HR, 1.99; 95% CI, 1.06–2.21; p=0.033). CONCLUSION: These results suggest that PLMS may be associated with increased mortality.