Is it Possible to Predict the Progression Rate in Korean IgA Nephropathy Patient?

Song, Young Soo; Kim, Jung Eun; Park, Ji Eun; Choi, Yongjun; Jung, Heesun; Kim, Mi Jung; Im, Byung Kook; Chung, Hyuck Joon; Yim, Hyunee; Shin, Gyu Tae; Kim, Heungsoo

Abstract

BACKGOUND: The progression rate of IgA nephropathy is known to be variable. We tried to draw an equation that can predict the interval till end stage renal disease (ESRD).
METHODS
We retrospectively checked the risk factors of the progression such as demographic, clinical, laboratory, and histologic data by using simple linear regression in eighty eight (M:F=53:35) patients with biopsy-proven IgA nephropathy from Oct 1994 to Aug 2004. By multiple linear regression, a semiquantitative equation estimating the rate of progression was developed. We also evaluated whether there is a "point of no return" that progresses to ESRD which was shown by D'Amico ('93) and Scholl ('99) by receiver operating characteristic (ROC) curve analysis.
RESULTS
Mean age and follow-up period were 34.1+/-13.6 years and 55.7+/-31.4 months. Among the risk factors, spot urine protein to creatinine ratio and mean arterial pressure during the follow-up period were significantly associated with the rate of progression (p<0.05). A semiquantitative equation estimating the rate of progression using the two factors was developed as follow. (delta)CCr=2.206-(0.128 x PCR(follow-up))-(0.023 x MAP(follow-up)) (MAPfollow-up:mean arterial pressure; regression coefficient=-0.023, PCRfollow-up:spot urine protein/creatinine; regression coefficient=-0.128). By ROC curve analysis, all patients with maximum serum creatinine over 4.1 mg/ dL during follow-up were found to progress to ESRD.
CONCLUSION
We conclude that in Korean IgA nephropathy patients we could predict the rate of decline in renal function for individual patients semiquantitatively and we could confirm the existence of a "point of no return" during the course of IgA nephropathy.