The Association of the Oxford Classification Score with Longitudinal Estimated Glomerular Filtration Rate Decline in Patients with Immunoglobulin A Nephropathy: A Mixed-Method Study

Ricong Xu; Zhijian Li; Tao Cao; Yi Xu; Ying Liao; Haiying Song; Xiaojie Chen; Fei Tang; Qiong Xiang; Qijun Wan

doi:10.2147/IJGM.S313333

The Association of the Oxford Classification Score with Longitudinal Estimated Glomerular Filtration Rate Decline in Patients with Immunoglobulin A Nephropathy: A Mixed-Method Study

Int J Gen Med. 2021 Jun 18:14:2655-2663. doi: 10.2147/IJGM.S313333. eCollection 2021.

Authors

Ricong Xu^{1

2}, Zhijian Li^{3

4}, Tao Cao^{1

2}, Yi Xu^{1

2}, Ying Liao^{1

2}, Haiying Song^{1

2}, Xiaojie Chen^{1

2}, Fei Tang^{1

2}, Qiong Xiang^{1

2}, Qijun Wan^{1

2}

Affiliations

¹ Department of Nephrology, The First Affiliated Hospital of Shenzhen University, Shenzhen, People's Republic of China.
² The Second People's Hospital of Shenzhen, Shenzhen, People's Republic of China.
³ Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, Guangdong, People's Republic of China.
⁴ Key Laboratory of Nephrology, National Health Commission and Guangdong Province, Guangzhou, Guangdong, People's Republic of China.

Abstract

Introduction: The Oxford Classification score, which predicts renal outcomes for immunoglobulin A nephropathy (IgAN), is widely used in clinical practice. Nevertheless, the relationship between these markers and longitudinal changes in renal function are poorly understood.

Methods: This was a population-based retrospective cohort study of 280 adults with biopsy-proven primary IgAN from 2011 to 2018. We used generalized additive mixed models to control for traditional kidney disease risk factors to analyze the associations between Oxford Classification MEST-C scores (mesangial hypercellularity, M; endocapillary hypercellularity, E; segmental glomerulosclerosis, S; tubular atrophy/interstitial fibrosis, T; crescents, C) and longitudinal changes in the estimated glomerular filtration rate (eGFR) after renal biopsy.

Results: The median eGFR was 78.2 mL/min/1.73 m² at baseline, and then it decreased on average by 1.3 mL/min/1.73 m² per year in the entire cohort. In adjusted models, compared with patients without relative lesions, the presence of T > 50% (T2) (-5.7; 95% confidence interval [CI], -9.5 to -2.0 mL/min/1.73m² per year) was associated with the fastest eGFR decline. S present (S1) (-2.9; 95% CI, -4.6 to -1.1 mL/min/1.73m² per year) and C > 25% glomeruli (C2) (-3.4; 95% CI, -6.4 to -0.5 mL/min/1.73m² per year) also demonstrated steeper eGFR declines. However, we found no association between M > 0.5 (M1), E present (E1), T 26%-50% (T1), and C present ≥ 1 glomerulus (C1), and progressive eGFR decline (p > 0.05).

Conclusion: The Oxford Classification scores, S1, T2, and C2, were independently associated with the longitudinal decreases in renal function in patients with IgAN. These findings suggested therapies targeted at improving early damage to these lesions might be essential to delay renal progression.

Keywords: IgA nephropathy; Oxford Classification; a mixed-method study; renal function decline.

Grants and funding

This work was supported by a grant from the National Natural Science Foundation of China (R.C.X., 81900639), the Basic Research Program of the Shenzhen Science and Technology R & D Fund (R.C.X., JCYJ20190806162807125), Shenzhen Key Medical Discipline Construction Fund, Shenzhen Second People’s Hospital Clinical Research Program (Y. X., 20193357002), Shenzhen Key Medical Discipline Construction Fund (SZXK009).