Cytomegalovirus nephritis in kidney transplant recipients: Epidemiology and outcomes of an uncommon diagnosis

BACKGROUND: Data on epidemiology and outcomes of cytomegalovirus (CMV) nephritis in kidney transplant patients are limited due to the rarity of this condition.

METHODS: A retrospective review of all kidney transplant recipients (KTR) (n = 6490) and biopsy-proven CMV nephritis between 1/1997 and 12/2020 was performed.

RESULTS: The prevalence of CMV nephritis was low: 13/6490 (0.2%). The diagnosis was made at a median of 7.0 months (range 2.6-15.6 months) after transplant. 6 of 13 (46%) patients were CMV (D+/R-). Median CMV DNA load at biopsy was 376,000, IU/mL (range 87,000-6,460,000 IU/mL). Main biopsy features were CMV glomerulitis (n = 7/13, 54%) followed by CMV tubulointerstitial nephritis (6/13; 46%). Mean eGFR at biopsy (22.7 ± 12 mL/min/1.73 m 2 ) was significantly decreased compared to baseline eGFR (38.7 ± 18.5 mL/min/1.73 m 2 , p = 0.02). The vast majority, 11 of 13 (85%), experienced graft failure including 5 of 13 (38%) death-censored. 5 of 13 (38%) patients were diagnosed with acute rejection: three had concurrent acute rejection, and two had rejection within 3 months of index biopsy, respectively. Patients with tubulointerstitial CMV nephritis were significantly more likely to have rejection at the time of biopsy (50% vs. 0%, p < 0.05) compared to those with glomerular CMV nephritis. There were no significant differences between these groups in terms of eGFR at all time points, death, graft failure, immunosuppression changes or rejection after biopsy.

CONCLUSION: CMV nephritis is rare but appears to be associated with poor patient/allograft outcomes. Early identification and timely treatment of CMV infection may prevent end-organ involvement and improve patient and allograft-related outcomes.