Lack of evidence that nephrolithiasis increases the risk of sialolithiasis: A longitudinal follow-up study using a national sample cohort

Objective: The objective of this study was to evaluate the risk of sialolithiasis in nephrolithiasis patients. Methods: Using data from the national cohort study from the Korean Health Insurance Review and Assessment Service, we selected 24,038 patients with nephrolithiasis. The control group consisted of 96,152 participants without nephrolithiasis who were matched 1:4 by age, sex, income, region of residence, diabetes, hypertension, and dyslipidemia. The incidence of sialolithiasis in the two groups was compared, with a follow-up period of up to 12 years. The crude and adjusted hazard ratio (HR) of nephrolithiasis to sialolithiasis was analyzed with a Cox-proportional hazard regression model. Results: The rates of sialolithiasis in the nephrolithiasis group and the control group were not significantly different (0.08% vs. 0.1%, P = 0.447). The crude and adjusted hazard ratios of nephrolithiasis to sialolithiasis were not statistically significant (crude HR = 0.82, 95% confidence interval [CI] = 0.50–1.35, P = 0.448; adjusted HR = 0.81, 95% CI = 0.49–1.33, P = 0.399). Subgroup analyses according to age and sex also failed to reveal statistical significance. Conclusion: There is no evidence of an increased risk of sialolithiasis associated with nephrolithiasis. We suggest that routine evaluation for sialolithiasis in all patients with nephrolithiasis is not necessary.