Seasonality of testicular torsion: A 10-year nationwide population based study

Purpose: Using a 10-year nationwide data set, we examined seasonal variability in the monthly incidence of testicular torsion in Taiwan. We also investigated the association between meteorological factors (ambient temperature, relative humidity, atmospheric pressure, rainfall and total hours of sunshine) and testicular torsion, stratified by age group. Materials and Methods: This study retrieved data from the National Health Insurance Research Database. We identified 1,782 hospitalizations for testicular torsion between 2000 and 2009. Spearman's rank correlation was used to explore possible associations between climatic parameters and the monthly incidence of testicular torsion. In addition, we used the ARIMA method (Auto-Regressive Integrated Moving Average) to test for seasonality in the incidence of testicular torsion. Results: The results demonstrated a fairly similar seasonal pattern in monthly incidence rates for testicular torsion across both age groups and the combined groups. January (midwinter) had the highest rates, which decreased in April to a trough in June (early summer). After adjusting for the time trend effect and climatic parameters, the ARIMA regression revealed that January had a significantly higher monthly incidence of testicular torsion compared to February. In addition, our results indicated that the monthly incidence of testicular torsion was negatively associated with ambient temperature. Conclusions: Our results suggest that the monthly incidence of testicular torsion was significantly associated with seasonality and ambient temperature.