Abstract

MORA ALVARADO, Darner A  and  CHAMIZO GARCIA, Horacio. Exploratory-ecological study on the relationship between the concentration of calcium salts in water for human consumption and the incidence of renal stones in Costa Rica. Rev. costarric. salud pública [online]. 2007, vol.16, n.31, pp.13-18. ISSN 1409-1429.

There are approximately 6000 cases per year of kidney stones in Costa Rica which implies an average rate of 1.7 cases per 1000 inhabitants; this pathology involves the formation of hard concretions resembling rock in any part of the urinary system. Etiology is multifactorial and involves anatomic, genetic, infectious as well as environmental factors such as the frequent intake of water with excess calcium salts also known as hard water. We carried out a county-based exploratory study of the ecologic type for the years 2001 to 2003 whereby a relationship was sought between the ingestion of calcium carbonate content in water for human consumption (which we abbreviate as (ACH) and the incidence of renal calculi. With this objective in mind, we used on the one hand, data on county-based, average water-hardness from the National Water Laboratory (LNA) from 4,000 water sources and, on the other, hospital discharges with the diagnosis of nephrolithiasis from 29 hospitals in the Costa Rican Social Security System. Statistical analysis was based on the Standardized Morbidity Index (which we abbreviate as IME) adjusted by the indirect method as well as the Pearson correlation coefficient taken to a 95% degree of confidence. To present the data, county maps of water hardness and IME of renal calculi were used. The results indicate an ecological association between the two variables; in other words, when there is greater consumption of hard water, there exists a greater risk of renal calculi in the population with an excess risk of 27% in those places having high levels of water hardness and a Pearson coefficient for the ecological correlation of r=0,25. On the other hand, in the areas where the water predominantly is not hard, the risk is inferior to the national average. The results obtained open up new questions regarding the relationship between water hardness as well as its consumption and the incidence of kidney stones which should be answered by future studies.

Keywords : calculi; lithiasis; hard water; associations; Costa Rica.

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