The correlation of interstitial change with renal prognosis in patients with myeloperoxidase-ANCA-associated glomerulonephritis: a single-center retrospective analysis

Objects We aim to explore the correlation between active/chronic tubulointerstitial injury and renal survival, and to compare their predictive value in patients with myeloperoxidase (MPO)-anti-neutrophil cytoplasmic antibody (ANCA)-associated glomerulonephritis (AAGN). Method A total of 225 patients with MPO-AAGN diagnosed between February 2004 and December 2020 were included. Survival and univariate/multivariate Cox regression analyses were used to analyze the prognostic value of interstitial inflammation and interstitial fibrosis/tubular atrophy (IF/TA). Results Of the 225 patients, 73 (32.4%) patients developed end-stage renal disease (ESRD) requiring maintenance dialysis. Interstitial inflammation>50% and IF/TA>50% were important predictors for ESRD in MPO-AAGN in multivariate Cox regression analysis adjusted by age, gender, estimated glomerular filtration rate (eGFR) <= 15 ml/min/1.73m(2), and normal glomeruli% (classified by <25%, 25-50%, >50%). Furthermore, we conducted stratified Cox regression analysis and found different results in the subgroups of eGFR>15 ml/min/1.73m(2) and eGFR <= 15 ml/min/1.73m(2). Interstitial inflammation>50% and IF/TA>50% were significant risk factors for ESRD in the subgroup of eGFR>15 ml/min/1.73m(2), but not or less significant in the subgroup of eGFR <= 15 ml/min/1.73m(2). Similarly, the survival analysis according to interstitial inflammation>50%/<= 50% and IF/TA>50%/<= 50% showed significant differences in the subgroup of eGFR>15 ml/min/1.73m(2), but not or less significant in the subgroup of eGFR <= 15 ml/min/1.73m(2). Conclusions Interstitial inflammation>50% and IF/TA>50% were prognostic factors for renal survival in MPO-AAGN. In particular, interstitial inflammation and IF/TA had a better predictive ability in the subgroup of eGFR>15 ml/min/1.73m(2). Key Points center dot Interstitial inflammation>50% and IF/TA>50% can help to predict renal survival in MPO-AAGN. center dot Both interstitial inflammation and IF/TA had a better predictive ability in the subgroup of eGFR>15 ml/min/1.73m(2) than those in the subgroup of eGFR <= 15 ml/min/1.73m(2).