The impact of ambient temperature on the incidence of urolithiasis: a systematic review and meta-analysis

Objective This review aimed to confirm the association between ambient temperature and incidence of urolithiasis and evaluate the impact thereof. Methods A systematic literature review was performed up to September 2019 using multiple databases. The effect of temperature on urolithiasis risk was assessed using risk ratio (RR). Pearson correlation coefficient (Pearson's r) was used to evaluate the linear association between ambient temperature and urolithiasis incidence. The non-linear association between climatic temperature and the urolithiasis incidence was also evaluated. Results Twenty-four studies related to the temperature and urolithiasis risk in 14 different countries or regions of five continent involving over 2.5 million cases were included in the meta-analysis. High climatic or work-place temperature was a significant risk factor of urolithiasis. The weighted correlation coefficient (Pearson's r) of monthly temperature and urolithiasis risk was 0.49 [95% confidence interval (CI) 0.40-0.57], a moderate correlation (0.4<0.6). According to non-linear models, as the daily temperature increases by 5 degrees C, the risk of urolithiasis will increase by 10% (95% CI 8-11%). Conclusion Both workplace and climatic temperatures are related to the incidence of urolithiasis. Public health intervention strategies need to be developed to prevent those in high-risk districts or occupations from being exposed to high ambient temperature.