Mean temperature and humidity variations, along with patient age, predict the number of visits for renal colic in a large urban Emergency Department: Results of a 9-year survey

Background: A marked geographic variability has been reported in stone disease, partially attributed to the Mean Annual Temperature (MAT), as well as to the seasonal fluctuations of climatic conditions. Accordingly, peaks in Emergency Department (ED) visits for renal colic are commonplace during the summer. Materials and methods: The aim of this study was to assess the influence of day-by-day climate changes on the number of visits as a result of renal colic in the ED (City of Parma, northern Italy, temperate continental climate). A total of 10,802 colic episodes were retrieved from the database during a period of 3286 days (January 2002 to December 2010). Results: The analysis of the data confirms a peak of renal colic cases during the summer, especially in July (maximum number of 4.1 cases of renal colic per day), and a winter nadir (minimum number of 2.7 cases of renal colic per day, in February). The linear regression analysis shows a high and significant correlation between the mean number of cases of renal colic per day and both the mean daily temperature (positive association, R = 0.93; p < 0.0001) and the mean daily humidity (negative association, R = −0.82; p < 0.0001). The influence of temperature and humidity on the incidence of renal colic cases varied widely among age groups, the highest incidence seen in patients aged between 30 and 40 years, and the lowest seen for those aged <20 and >70 years of age. Conclusion: The combined data suggest that the hot and dry climate would favor an acceleration of the process of stone formation, which seems more pronounced in the older population.