A decreased waist area is a risk factor for recurrent nephrolithiasis after retrograde ureteroscopy

OBJECTIVE Obesity and metabolic syndrome have been identified as risk factors for nephrolithiasis. While dietary improvements and exercise effectively prevent cardiovascular disease, their impact on recurrent nephrolithiasis has not been well studied. We aimed to elucidate the association between changes in body shape and recurrent nephrolithiasis. METHODS Patients who underwent computed tomography (CT) twice at intervals of more than 12 months after retrograde ureteroscopy to treat upper urinary stones from January 2014 to December 2021 in our hospital were retrospectively included. The changes in waist area (WA) according to CT, age, sex and body mass index (BMI) at surgery were compared with those of patients who experienced recurrence and those who did not experience recurrence via univariate and multivariate analyses. RESULTS A total of 109 patients were included in this study, with 56 patients in the recurrence group and 53 patients in the nonrecurrence group. The median age was younger in the recurrence group than in the nonrecurrence group (61.5 versus 71 years). The median BMI was 23 in both groups. The rate of recurrence in female patients with a decreased WA was greater than that in those with an increased WA (n = 12/19 versus 6/23) (p = 0.0277). Age under 70 years and decreased WA were significant risk factors for the recurrence of renal stones according to multivariate analysis (p < 0.05). CONCLUSION A decreased WA on CT images is a risk factor for recurrent nephrolithiasis after retrograde ureteroscopy, especially in female patients.