Living Arrangement Affects Urine Na/K Ratio Among 44,085 Residents: Tohoku Medical Megabank Project Community-Based Cohort Study

Introduction: High dietary sodium-to-potassium (Na/K) ratio contributes to increased risk of cardiovascular disease (CVD) events. Previous studies on Japanese people suggested that women living in a multi-generational household (i.e., with spouse-children-parents; or spouse-parents) had a 2-3 fold higher risk of CVD events than women living with spouses only. However, few studies have examined the effect of living arrangement on urinary (U) Na/K. We clarified whether those living in a multi-generational household had higher UNa/K than those living with spouses only. Methods: We analyzed data of 44,085 residents (20-74 years), enrolled in the Tohoku Medical Megabank Project Community-based Cohort (TMM CommCohort) Study. UNa/K ratios were derived by dividing urinary Na levels (mEq/L) by urinary K levels (mEq/L) using spot urine samples. Participants were categorized into “living with spouse only”, “living with spouse and children”, “living with spouse and parents”, “living with parents and children”, “living with child only”, and “living with spouse, children and parents”. Using analysis of covariance, multivariate-adjusted geometric means of UNa/K ratios in each group were calculated by sex, with adjustments for other variables. Results: Those in a multi-generational household with spouse-children-parents had significantly higher multivariate-adjusted geometric means of UNa/K ratios in both sexes than those living with spouses. In male, those in a multi-generational household with spouse-childrenhad significantly higher multivariate-adjusted geometric means of UNa/K ratios than those living with spouses. In female those in a multi-generational household with spouse-parents or with children-parents had significantly higher multivariate-adjusted geometric means of UNa/K ratios than those living with spouses. Conclusions: This study suggests that those living in a multi-generational household have higher UNa/K ratios, which might contribute to an increased risk of CVD events.