Natural history of immunoglobulin A nephropathy and predictive factors of prognosis: a long-term follow up of 204 cases in China.

AIM: Immunoglobulin A nephropathy (IgAN) is the most common primary glomerulonephritis worldwide. However, its natural history and risk factors are not well understood. Our aim was to identify the clinical and pathological factors that could predict disease prognosis in Chinese patients.

METHODS: We studied 204 biopsy-diagnosed IgAN patients, who were followed for an average of 6.1 years (range, 4-15 years). Chronic kidney disease (CKD) classified according to the Kidney Disease Outcomes Quality Initiative practice guidelines. Renal pathological lesions were graded single-blindedly according to the Haas classification. The glomerular filtration rate was estimated by the Modification of Diet in Renal Disease equation for Chinese subjects.

RESULTS: Patients with CKD were classified as stage 1 (38.10%), stage 2 (35.40%), stage 3 (13.30%), stage 4 (9.90%) and stage 5 (3.30%). During the follow up, 31 patients had progressed to end-stage renal disease. The renal survival rate following biopsy was 85.1% at the fifth year, and 77.1% at the 10th year. Univariate analysis indicated that patients who were male, had hypertension, proteinuria of more than 1 g/day, renal impairment (estimated glomerular filtration rate, <60 mL/min.1.73 m(2)), and a high histological grading were associated with poor prognosis. Multivariate analysis indicated that the relative risk of renal failure for patients was 3.9 (P = 0.000) for patients with renal impairment, 2.8 (P = 0.019) for patients with hypertension, and 2.0 (P = 0.003) for patients with high histological grading.

CONCLUSION: We described the natural history of IgAN through follow ups of a relatively large cohort of patients. Most patients were biopsied at an early stage; however, the long-term prognosis was still poor. Patients with renal impairment, hypertension and advanced histological involvement had the highest risk for disease progression.