Certain clinical and pathologic factors predict which patients with IgA nephropathy (IgAN) are at higher risk for progressing to end-stage renal disease (ESRD) within 10 years, according to Chinese researchers.
Danhua Shu, MD, and colleagues of First Affiliated Hospital of Wenzhou Medical University in China, compared 50 IgAN patients who had a renal survival time of less than 10 years (ESRD cases) with 100 IgAN patients who had a renal survival time of more than 10 years (controls). The patients were diagnosed with primary IgAN from 1997 to 2012.
At the time of biopsy, cases had significantly higher frequencies of Oxford classification M1 (50% or more mesangial hypercellularity), S1 (presence of segmental glomerulosclerosis) and T1 and T2 disease (greater than 25% and 50% tubular atrophy/interstitial fibrosis, respectively) compared with controls. Cases also had lower mean estimated glomerular filtration rate (eGFR, 57.3 vs 95.7 mL/min/1.73 m2). Cases also had higher mean levels of serum creatinine (1.4 vs 0.9 mg/dL), uric acid (UA, 8.0 vs 5.7 mg/dL), total cholesterol (207.7 vs 184.6 mg/dL), and 24-hour urine protein, lower mean hemoglobin (Hb) levels (12.2 vs 12.9 g/dL) and a greater proportion of patients with hypertension (62.0% vs 47.0%), the investigators reported in a paper published online ahead of print in BMC Nephrology.
In multivariate analysis, only M1 disease and low eGFR at biopsy and elevated time-averaged UA level and low time-averaged Hb level during follow-up emerged as independent risk factors for ESRD.
“In summary, patients with pathological assessment of M1, T1 or T2, an impaired renal function, abnormal blood biochemical parameters and hypertension at biopsy should be paid more attention, and therapies aiming to keep UA and Hb levels under control and reduce urinary protein during the follow-up are highly recommended,” Dr. Shu and colleagues wrote.
In the current study, T score did not have a marked role in multivariate analysis, but it correlated with most variables in the study, Dr Shu’s team stated. Combined with other study findings, they hypothesize that M1 score may be a risk factor for ESRD progression in the Chinese population.
Hyperuricemia can cause both mechanical and inflammatory damage to the kidneys. Although urinary protein was not identified as a risk factor for renal failure in multivariable analysis, it has long been recognized as important to renal outcomes, according to the investigators.
The researchers noted that the retrospective design of the study was a limitation. They also acknowledged a selection bias. The patients enrolled in the study were those who followed up in their hospital long-term, so they might not be fully representative of the general population.
1. 1. Shu D, Xu F, Su Z, et al. Risk factors of progressive IgA nephropathy which progress to end stage renal disease within ten years: a case–control study. BMC Neph. doi: 10.1186/s12882-016-0429-x. [Epub ahead of print]