A PAINFUL TRUTH: CLIMATE CHANGE AND KIDNEY STONE DISEASE

A likely direct health effect of global warming is the northward expansion of the present-day southeastern U.S. kidney stone “belt”. The fraction of U.S. population living in high risk zones for nephrolithiasis will grow from 40% in 2000 to 56% by 2050, and to 70% by 2095. Predictions based on a climate model of intermediate severity warming (SRESa1b) indicate a climate-related increase of 1.6-2.2 million lifetime cases of nephrolithiasis by 2050, representing up to a 30% increase in some climate divisions. Nationwide, the cost increase associated with this rise in nephrolithiasis would be $0.9-1.3 billion annually (Y2K dollars), representing a 25% increase over current expenditures. The impact of these changes will be geographically concentrated, depending on the precise relationship between temperature and stone risk. Stone risk may abruptly increase at a threshold temperature (non-linear model), or increase steadily with temperature change (linear model), or some combination thereof. The linear model predicts increases by 2050 that are concentrated in California, Texas, Florida and the Eastern Seaboard; the non-linear model predicts concentration in a geographic band stretching from Kansas to Kentucky and Northern California, immediately south of the threshold isotherm.

A similar trend will occur worldwide, particularly in Southern Europe, Asia and the Far East. Increased prevalence of kidney stones will have a far greater impact on morbidity in developing countries in this region.