Factors Associated with Compliance to Increased Fluid Intake and Urine Volume Following Dietary Counseling in First-Time Kidney Stone Patients.

Abstract

Increasing fluid intake to achieve a urine volume (UV) of >2.5 L/day decreases stone events. We assessed compliance rates and demographic and clinical variables associated with increased fluid intake and UV in patients with urolithiasis following dietary counseling. In a retrospective study, patients with a low baseline UV (<2.5 L/day) on an initial 24-hour urine collection during metabolic stone evaluation were identified between 2010 and 2015. Patients received detailed standardized dietary counseling, including increasing fluid intake to >3 L/day and titrating it to achieve UV >2.5 L/day. A follow-up 24-hour urine collection was performed at 6 months (FU1) and 18 months (FU2) to assess compliance (UV >2.5 L/day) and predictors associated with it. Our cohort contained 363 patients, 53.4% men and 46.6% women. The mean UV of baseline, FU1, and FU2 urine collections was 1.63, 2.52, and 2.48 L, respectively. The compliance rate of obtaining UV of >2.5 L was 50.1% at 6 months. On logistic regression, male sex (odds ratio [OR] 3.27, 95% confidence interval [CI] 1.94, 5.52, p < 0.001), urolithiasis-related procedures such as ureteroscopy (OR 2.31, 95% CI 1.20, 4.42, p = 0.01) or percutaneous nephrolithotomy (OR 3.48, 95% CI 1.58, 7.63, p = 0.002), and baseline 24-hour UV >1 L (OR 3.00, 95% CI 1.02, 8.76, p = 0.04) were associated with greater odds of compliance. Age >58 years (OR 0.39, 95% CI 0.20, 0.75, p = 0.005) and presence of lower urinary tract symptoms (OR 0.50, 95% CI 0.26, 0.95, p = 0.03) were associated with lower odds of compliance. Ethnicity, body mass index, renal function, marital status, renal stone burden, stone type, and household income were not associated with compliance. In stone formers, compliance to fluid intake recommendations as measured by 24-hour UV is roughly 50%. Understanding risk factors for noncompliance, especially in at risk patients, can be used for quality improvement initiatives and reducing stone events.