Seasonal alterations in nocturia and other storage symptoms in three Japanese communities

To conduct a community-based questionnaire study to uncover the relationship between climates and lower urinary tract symptoms.

A total of 6000 residents aged 41 to 70 years were randomly selected in three Japanese towns (Tobetsu in a subartic zone, Kumiyama in a temperate zone, and Sashiki in a subtropical zone). A self-administered questionnaire, which included the International Prostate Symptom Score, and overall incontinence score from the International Consultation on Incontinence Questionnaire Short Form was mailed to one half of the targets in the summer and the remaining one half in the winter. A logistic regression model was used for the main statistical analysis, with P <0.05 considered significant.

A total of 1124 responses (37.5%) to the summer study and 1156 (38.5%) to the winter study were available for analysis. Three storage symptoms (frequency, urgency, and nocturia) demonstrated statistically significant differences between the two seasons. Multivariate logistic regression analysis revealed that winter was an independent risk factor of frequency (score of 1 or more, P <0.0001, odds ratio [OR] 1.47; and score of 2 or more, P = 0.0089, OR 1.30), urgency (score of 1 or more, P = 0.0022, OR 1.38), and nighttime voiding (score of 2 or more, P = 0.0012, OR 1.40). This tendency was marked in the subtropical zone but was not observed in the subartic zone.

These findings suggest that epidemiologic studies focusing on the prevalence of lower urinary tract symptoms should take into consideration the impact of seasonal changes, especially in communities in warmer zones.