Familial Relations and Recurrence Pattern in Nephrolithiasis: New Words About Old Subjects

Purpose: While medical and surgical approaches to urolithiasis are different for single and recurrent stone former (RSF), the RSF definition itself is commonly overlooked. Moreover, despite consensus on association between family history (FH) and urolithiasis, more epidemiologic evidence is requiredto clarify the nature of this relationship. Our purpose was to propose a more precise definition of RSF, and also to investigate how family history may affect urolithiasis.Materials and Methods: Using a multistage stratified sampling in 4 seasonal phases, 6127 subjects with imaging-proven urolithiasis were detected in 12 Iranian regions. The FH of urolithiasis and the average interval between episodes (cycles) were determined by an informed interview. Results: Of 6127 patients with the mean age of 41.8 ± 15.1 years, 42% had FH, and 22.2% were RSF of whom 61% were men. The patients with FH had a greater chance of recurrence (OR = 1.2, 95% Confidence Interval (CI), 1.1 to 1.4). Furthermore, patients with positive FH had more episodes (P = .0001), comparable cycles and younger ages at the onset (P = .02) than those patients without a FH. In the RSF group, the 90th percentiles of the cycle were 60 months and the estimated mean stone cycle for the population was 25.34 months (99% CI, 23.0 to 27.7).Conclusion: Family history seems very common in Iranian population and is a risk factor for recurrence. Moreover, RSF could be identified by the estimated average cycle in the population (25.3 months) or by the percentiles