A High Basal Metabolic Rate Is An Independent Predictor Of Stone Recurrence In Obese Patients

Purpose: Basal metabolic rate (BMR) is an indicator of overall body metabolism and may portend unique aberrations in urine physico-chemistry and stone recurrence. The present study examined the effect of predicted BMR on 24 hours urinary metabolic profiles and stone recurrence in obese stone patients.Materials and Methods: Data from 308 obese patients (body mass index [BMI] >= 30 kg/m(2)) diagnosed with urinary stone disease between 2003 and 2015 were analyzed retrospectively. BMR was calculated using the Harris-Benedict equation, and patients were classified into two predicted BMR categories (<1,145 kcal/day, >= 1,145 kcal/day). Urinary metabolic parameters and risk of stone recurrence were compared between the two groups.Results: The high BMR group was more likely to be younger and female, and to have a high BMI and lower incidence of diabetes than the low BMR group (each p<0.05). There was a positive correlation between BMR and 24 hours urinary sodium, uric acid, and phosphate excretion. The amounts of stone-forming constituents such as calcium and uric acid were significantly higher in the high BMR group. Kaplan-Meier estimates showed that the high BMR group had a significantly shorter stone recurrence-free period than the low BMR group (log-rank test, p<0.001). Multivariate Cox regression analyses revealed that predicted BMR was an independent factor of stone recurrence (hazard ratio, 2.759; 95% confidence interval, 1.413-5.386; p=0.003).Conclusions: BMR may be an easily measured parameter that can be used to identify risk of stone recurrence in obese stone patients.