Urinary Sodium Excretion and Kidney Disease Progression in IgA Nephropathy: A Cohort Study.

Introduction: The role of dietary sodium intake in the risk of chronic kidney disease progression remains controversial. This study aimed to evaluate the association of urinary sodium excretion and progression of IgA nephropathy.

Methods: We assessed 596 patients with IgA nephropathy, and urinary sodium excretion was measured at the time of kidney biopsy. Cox proportional hazards models and restricted cubic splines were used to assess the association between urinary sodium excretion and kidney disease progression events, defined as 50% eGFR decline or development of kidney failure.

Results: After a mean follow-up of 58.9 months, a total of 75 (12.6%) participants of IgA nephropathy reached composite kidney disease progression events. The risk of kidney disease progression events was higher in patients with higher urinary sodium excretion. After adjustment for traditional risk factors, higher levels of ln-transformed urinary sodium excretion was associated with the kidney disease progression events in patients with IgA nephropathy (HR: 2.1; 95% CI: 1.4-3.2). In reference to the first tertile of urinary sodium excretion, hazard ratios were 1.9 (95% CI: 1.0-3.4) for the second tertile and 2.1 (95% CI: 1.1-3.9) for the third tertile.

Conclusion: Higher levels of urinary sodium excretion were associated with kidney disease progression events in IgA nephropathy independent of clinical and biopsy characteristics.