Non-Linear Association Between Climatic Parameters and Bell’s Palsy Prevalence of Hospital Outpatients: An Ecological Proof in Kunshan, Suzhou, China

Abstract

Objective This study aimed to explore the relationship between climatic parameters and the daily cases of Bell’s palsy (BP) among hospital outpatients, providing ecological evidence for understanding BP etiology and prevention. Methods Retrospective analysis was conducted on data from 2187 BP patients who attended Kunshan First People’s Hospital Outpatient Clinic from January 1, 2020, to December 31, 2022. Meteorological data, including temperature, relative humidity, precipitation, wind speed, sunshine duration, and atmospheric pressure, were collected and combined with daily BP case records. Additionally, air quality index was used as a covariate. Results The number of new BP cases among outpatients showed a negative correlation with average daily temperature. A nonlinear relationship between daily average temperature and BP cases was observed through the generalized additive model (GAM). A significant negative correlation was identified between daily average temperature and BP cases, with inflection points at temperatures above 4.2°C, suggesting a potential decrease in BP risk with temperature rise beyond this threshold. Conclusion This study provides ecological evidence of a link between climatic factors and BP occurrence. Temperature demonstrated a significant nonlinear negative correlation with daily BP incidence, highlighting temperature and cold exposure as key targets for BP prevention in Kunshan.