[Multivariate analysis of predictive factors in the evolution of renal lithiasis].

OBJECTIVE To perform a multivariate statistical analysis of epidemiological, clinical and biochemical factors that make it possible to identify the variables that can independently predict the course of renal lithiasis, thus defining a group at risk of worse evolution. MATERIAL AND METHODS A retrospective, descriptive and analytic study was in a cohort of 248 patients with kidney stones treated in our center from 2003 to 2007. A univariate (chi-square) and multivariate analysis (regression model) of possible epidemiological predictive factors (age, gender), clinical data of stones (number, localization, size and bilaterality) and biochemical factors (urinary composition, stone composition) were analyzed. RESULTS Based on a mean follow-up of 60 months (95% CI: 52.5-67.4) we observed a global persistence of kidney stones in 121 patients (48.8%), 127 patients being stone-free (51.2%). The univariate analysis describes the following variables as being associated to greater persistence of lithiasis: age, number of stones, calyceal localization and bilaterality, urinary biochemical composition, and stone biochemical composition. In regards to all of the above variables, only age less than 47 years, bilaterality, stone localization and chemical composition of the lithiasis (oxalate calcium dehydrated) were significantly associated to a major risk of persistence of kidney stones. CONCLUSION There is a high persistence rate of kidney stones. Patient age inferior to 47 year, calyceal localization, bilaterality, and biochemical composition of stones (oxalate calcium dihydrate) are independent factors associated to higher persistence rate of kidney stones. These factors indicate a risk group with a worse clinical prognosis in which we should reconsider more individualized diagnostic and therapeutic strategies.