[Risk factors affecting the long-term outcome of IgA nephropathy].
OBJECTIVE
To study the risk factors predicting long-term renal survival of IgA nephropathy in Chinese.


METHODS
Clinical and pathological data of 317 patients (124 males and 193 females) with IgA nephropathy confirmed by renal biopsy in our center from January 1987 to February 2003 were reviewed retrospectively and were correlated with outcomes. A semiquantitative scoring system was used to evaluate individual pathological lesion of the kidney. Patients were followed for at least 6 months and doubling of serum creatinine level was defined as endpoint of follow-up. Renal survival was calculated by Kaplan-Meier survival analysis and risk factors of progression were analyzed by using univariate and multi-variate Cox regression models.


RESULTS
The average age at renal biopsy was (30.1 +/- 10.9) years and the average duration from onset of disease to the time of biopsy was (20.1 +/- 33.7) months. Thirty-two percent of the patients had 24 h-urinary protein excretion greater than 1.0 g at the time of biopsy. Thirty-two percent of the patients had hypertension and 20.8% had renal insufficiency. Thirty-five percent of the patients were of Lee's grade IV or above and 20.5% presented with small proportion of crescent formation (usually less than 20%). Patients were followed for an average duration of (43.5 +/- 32.2) months with 39 patients (12.3%) reaching the endpoint. The 1-, 3-, 5- and 10-year renal survival was 99.5%, 93.1%, 84.5% and 60.1% respectively. Univariate Cox regression analysis revealed that longer duration of the disease before biopsy, serum creatinine > 115 micromol/L, proteinuria > 1.0 g/d, hypertension, Lee's grading of IV-V, moderate-severe glomerulosclerosis, crescent formation, moderate-severe interstitial fibrosis and renal arteriolar lesion were risk factors of disease progression, with an odds ratio of 1.007, 9.61, 7.31, 3.97, 5.41, 5.78, 4.65, 14.05 and 2.28 respectively (P < 0.001). Episodic macro-hematuria had an odds ratio of 0.194 (P < 0.05). Age, sex, serum cholesterol and triglyceride level had no significant impact on prognosis. Proteinuria, elevated serum creatinine, glomerulosclerosis, crescent formation and interstitial fibrosis were confirmed to be independent risk factors by multi-variate Cox regression model while the remaining variables were not statistically significant. Patients with both renal insufficiency and proteinuria greater that 1.0 g/24 h at the time of biopsy had a very poor 5-year renal survival (41.8%).


CONCLUSIONS
Proteinuria, renal insufficiency, glomerulosclerosis, crescent formation and interstitial fibrosis were independent risk factors predicting the renal survival. IgA nephropathy presented with proteinuria, hypertension and crescent formation may need intervention.
Yang
Nian-sheng
NS
Department of Nephrology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China. nianyh@pub.guangzhou.gd.cn
Wu
Qing-qing
QQ
Du
Yong
Y
Zhang
Rui
R
Li
You-ji
YJ
Ye
Ren-gao
RG
Yu
Xue-qing
XQ
D000293:Adolescent; D000328:Adult; D001706:Biopsy; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D005922:Glomerulonephritis, IGA / Q000401:mortality* / Q000473:pathology; D006801:Humans; D007668:Kidney / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D016019:Survival Analysis