Factors related to renal cortical atrophy development after glucocorticoid therapy in IgG4-related kidney disease: a retrospective multicenter study

Abstract

Background: In immunoglobulin G4-related kidney disease (IgG4-RKD), focal or diffuse renal cortical atrophy is often observed in the clinical course after glucocorticoid therapy. This study aimed to clarify the factors related to renal atrophy after glucocorticoid therapy in IgG4-RKD.

Methods: We retrospectively evaluated clinical features including laboratory data and computed tomography (CT) findings before and after glucocorticoid therapy in 23 patients diagnosed with IgG4-RKD, all of whom were followed up for more than 24 months.

Results: Seventeen patients were men, and six were women (average age 62.0 years). Average follow-up period was 54.9 months. The average estimated glomerular filtration rate (eGFR) at diagnosis was 81.7 mL/min/1.73 m². All patients had had multiple low-density lesions on contrast-enhanced CT before glucocorticoid therapy, and showed disappearance or reduction of these lesions after it. Pre-treatment eGFR and serum IgE level in 11 patients in whom renal cortical atrophy developed 24 months after the start of glucocorticoid therapy were significantly different from those in 12 patients in whom no obvious atrophy was found at that time (68.9 ± 30.1 vs 93.5 ± 14.1 mL/min/1.73 m², P = 0.036, and 587 ± 254 vs 284 ± 263 IU/mL, P = 0.008, respectively). Pre-treatment eGFR and serum IgE level were also significant risk factors for renal atrophy development 24 months after the start of therapy with an odds ratio of 0.520 (per 10 mL/min/1.73 m², 95% confidence interval (CI) 0.273-0.993, P = 0.048) and 1.090 (per 10 IU/mL, 95% CI: 1.013-1.174, P = 0.022), respectively, in age-adjusted, sex-adjusted, serum IgG4 level-adjusted logistic regression analysis. Receiver operating characteristic curve analysis showed that eGFR of less than 71.0 mL/min/1.73 m² and serum IgE of more than 436.5 IU/mL were the most appropriate cutoffs and yielded sensitivity of 63.6% and specificity of 100%, and sensitivity of 90.9% and specificity of 75.0%, respectively, in predicting renal atrophy development.

Conclusions: This study suggests that pre-treatment renal insufficiency and serum IgE elevation predict renal atrophy development after glucocorticoid therapy in IgG4-RKD.

Keywords: Atrophy; Glucocorticoid; IgG4-related disease; IgG4-related kidney disease.

Fig. 1

Low-density lesions after glucocorticoid therapy. The outcome of low-density lesions after glucocorticoid therapy varied between individual patients and even between individual lesions: a, c, e, g pre-treatment; b, d, f, h post-treatment. Representative cases are shown: patient 10 (a, b); patient 15 (c, d); patient 17 (e, f); patient 22 (g, h). Patient 10 had small peripheral cortical nodules. Patients 15 and 17 had multiple, round or wedge-shaped lesions. Patient 22 had diffuse patchy involvement. Arrows show recovering lesions, and arrowheads show atrophic lesions

Fig. 2

Three-dimensional computed tomography (CT). Three-dimensional CT revealed the appearance of multiple renal cortical scars resembling craters. Patient 22 (c, d) with worse pre-treatment estimated glomerular filtration rate (35.4 mL/min/1.73 m²) than patient 17 (69.3 mL/min/1.73 m²) (a, b) had many more cortical scars. Arrows show atrophic lesions

Fig. 3

Receiver operating characteristic curve (ROC) analysis. a ROC curves to identify the appropriate estimated glomerular filtration rate (eGFR) cutoffs for the prediction of renal atrophy development show that eGFR <71.0 mL/min/1.73 m² yields sensitivity of 63.6% and specificity of 100% (circle). b ROC curves to identify the appropriate serum IgE level cutoffs for the prediction of renal atrophy development show that serum IgE >436.5 IU/mL yields sensitivity of 90.9% and specificity of 75.0% (circle). AUC area under the curve