Serum Uric Acid Level Predicts Progression of IgA Nephropathy in Females but Not in Males.

PloS one

PubMedID: 27560997

Nagasawa Y, Yamamoto R, Shoji T, Shinzawa M, Hasuike Y, Nagatoya K, Yamauchi A, Hayashi T, Kuragano T, Moriyama T, Isaka Y, Nakanishi T. Serum Uric Acid Level Predicts Progression of IgA Nephropathy in Females but Not in Males. PLoS ONE. 2016;11(8):e0160828.
BACKGROUND
Immunoglobulin A nephropathy (IgAN) is one of most common forms of glomerulonephritis. At this point, the clinical impact of hyperuricemia on IgAN is not clear. The aim of the present study was to explore the clinical impact of hyperuricemia on the progression of IgAN.

STUDY DESIGN
Multicenter retrospective cohort study.

SETTING & PARTICIPANTS
935 IgAN patients who were diagnosed by kidney biopsy at Osaka University Hospital, Osaka General Hospital, and Osaka Rosai Hospital. were included in this study.

PREDICTOR
Uric acid levels at renal biopsy.

OUTCOMES
The outcome of interest was the time from the kidney biopsy to the time when a 50% increase in the baseline serum creatinine level was observed, which was defined as "progression".

MEASUREMENTS
The baseline characteristics according to the kidney biopsy at the time of diagnosis were collected from the medical records, and included age, gender, body mass index, hypertension, diabetes (use of antidiabetic drugs), serum levels of creatinine, urinary protein, smoking status, RAAS blockers and steroid therapy.

RESULTS
An elevated serum uric acid level was an independent risk factor for progression in female patients (per 1.0 mg/dL, multivariate-adjusted incident rate ratio 1.33 [95% confidence interval 1.07, 1.64], P = 0.008) but not in male patients (1.02 [0.81, 1.29], P = 0.855). To control a confounding effect of renal function on an association between serum uric acid level and progression in female patients, age- and serum creatinine-matched and propensity score-matched analyses were performed, and these results also supported the effect by uric acid on kidney disease progression independent of basal kidney function.

LIMITATIONS
A cohort analyzed retorospectively.

CONCLUSIONS
This study revealed that an elevated uric acid level was an independent risk factor for ESKD in female IgAN patients. Therefore, uric acid might be a treatable target in female IgAN patients.