Zhu B, et al. - Researchers sought for the role of serum uric acid (SUA) level in the progression of Immunoglobulin A nephropathy (IgAN). A possible positive association of SUA level with IgAN progression was suggested. In patients with elder age, lower estimated glomerular filtration rate [eGFR], or tubular atrophy/interstitial fibrosis, a less significant association of hyperuricemia with IgAN progression was observed, probably due to some more confounders in association with the IgA progression in these patients.

Methods

• Researchers used a cohort of 1,965 cases with biopsy-proven IgAN in order to assess the associations of SUA concentration with the primary outcome of a composite of all-cause mortality or kidney failure (defined as a reduction of estimated glomerular filtration rate [eGFR] by 40% from baseline, requirements for dialysis and transplantation), or the outcome of kidney failure alone, using Cox and logistic regression models, respectively, with adjustment for confounders.

Results

• According to data, the mean age was 33.37 ± 11.07 years, eGFR was 101.30 ± 30.49 mL/min/1.73 m², and mean uric acid level was 5.32 ± 1.76 mg/dL at baseline.
• They reported 317 cases reached the composite outcome of all-cause mortality (5 deaths) or kidney failure (36 cases of dialysis, 5 cases of renal transplantation, and 271 cases with reduction of eGFR by 40% from baseline) during a median of 7-year follow-up.
• In the Cox proportional hazards regression models adjusted for demographic and IgAN specific covariates and treatments, a higher quartile of uric acid linearly related to an increased risk of the primary outcome (highest vs lowest quartile, hazard ratio [HR] 2.39; 95% CI 1.52–3.75) and kidney failure (highest vs lowest quartile, HR 2.55; 95% CI 1.62–4.01) was demonstrated.
• In the continuous analysis, association of 1 mg/dL greater uric acid level with 16% increased risk of primary outcome (HR 1.16, 95% CI 1.07–1.25) and 17% increased risk of kidney failure (HR 1.17, 95% CI 1.08–1.27), respectively, was evident in the fully adjusted model.
• Consistent results were drawn by multivariate ­logistic regression analyses for the sensitive analyses.
• The subgroup analyses revealed significant interactions that a higher association of SUA with the incidence of the primary outcome was present in patients with mean arterial pressure (MAP) < 90 mm Hg or mesangial hypercellularity vs those with MAP ≥90 mm Hg or those without mesangial hypercellularity, respectively.
• No significant association of hyperuricemia with the risk of developing the primary outcome in elder patients (≥32 years old), patients with eGFR < 90 mL/min or with tubular atrophy/interstitial fibrosis, was observed.