Familial aggregation of urolithiasis: findings from a Nationwide Middle Eastern study

This study aimed to determine the potential effect of genetic factors and positive family history on the familial aggregation of urolithiasis in Iran. Of the total 44,186 participants in the Iran National Stone Survey (INSS) database, 34,953 individuals who were members of 8629 nuclear families were included in this study. The mean prevalence of urolithiasis was 5.7% [95%CI: 5.5 - 6.0%] in this subpopulation. Familial aggregation of urolithiasis was analyzed in 34,745 participants (99.6% of those originally included) utilizing a multivariable logistic regression with second order generalized estimating equations approach (GEE2) to adjust for sex, age, urbanization status and ethnicity. Recurrence risk ratios (λ) were used to evaluate the degree of familial aggregation. Our multivariable analysis demonstrated a strong familial aggregation of urolithiasis within sibling pairs (λ_s = 78.35), parent-offspring pairs (λ_o = 40.12) and spouse pairs (λ_sp = 21.62). The respective ORs were 5.65 [95%CI: 3.49, 9.14] for siblings, 2.85 [95%CI: 2.20, 3.68] for parents and 1.27 [95%CI: 1.06, 1.54] for spouses. Urinary stone disease tends to aggregate in families with a positive history of urolithiasis in either the parents or siblings. Siblings have a more prominent effect in inducing familial aggregation compared to parents. Despite the prominent role of familial genetic components in urolithiasis aggregation, shared environmental factors appear to partake in this phenomenon to some extent, as suggested by urolithiasis aggregation among spouse pairs.