ABSTRACT
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 required to 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. 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. 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 90[th] 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]. 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