Nonlinear effects of ambient temperature and treatment days on nocturnal enuresis using generalized additive models

To examine the effects of the average daily ambient temperature and treatment days on the outcomes of patients with nocturnal enuresis (NE), a common urinary symptom in children. The panel data of 19 children with NE (12 boys and 7 girls; median age: 9 years; age range: 6-15) were prospectively collected (up to 1,469 days; total number of records: 3194). NE status (presence of incontinence), treatment type, and weather-related variables (ambient temperature, precipitation, sunshine hours, and barometric pressure) were recorded. Factor analyses were subsequently performed using a generalized additive model (GAM). Among the patient features, treatment type, and weather-related variables, the average daily ambient temperature and treatment days were identified as risk factors for NE. Specifically, NE risk increased with an average daily ambient temperature of < 16.7 °C and decreased with a daily average ambient temperature of > 20.1 °C. An inverse correlation between NE risk and treatment days was observed in all cases. Notably, long-term treatment of approximately ≥ 1465 days significantly reduced the NE risk, despite repeated exacerbations. The average daily ambient temperature and treatment days affect the risk of NE.