Risk Factors for Pneumocystis Jirovecii Pneumonia Among Kidney Transplant Recipients in Southeast France: A 10 Years Case-Control Study.

BACKGROUND

Pneumocystis jirovecii is an opportunistic fungus responsible for Pneumocystis pneumonia (PJP) in hosts with impaired cell-mediated immunity, particularly solid organ transplant recipients. The aim of our study was to identify risk factors associated with PJP in kidney transplant recipients (KTRs).

METHODS

We conducted a single-center, retrospective, case-control study (1 case per 2 controls) of KTRs from May 2014 to May 2024. Cases were defined as KTRs with a confirmed diagnosis of PJP, while controls were matched on transplant and hospitalization dates (±3 months) and had not developed PJP during the follow-up period. Statistical analysis was performed using conditional logistic regression models to examine potential risk factors for PJP, with a forward stepwise selection procedure to identify significant variables.

RESULTS

A total of 37 KTRs with PJP and 74 matched controls were included. The median time from transplantation to diagnosis was 60 months. Two cases occurred before prophylaxis was discontinued, followed by 11 cases within the next six months. Baseline characteristics were similar between cases and controls. The number of day hospital or outpatient visits in the year prior to inclusion was significantly higher in cases than in controls (mean 11.11 vs. 8.89 visits, p = 0.04). Severe lymphopenia (<0.5 G/L) was the most significant risk factor for the development of PJP.

CONCLUSIONS

The most significant risk factor observed was severe lymphopenia. These findings underscore the importance of strengthening infection prevention measures, including strict adherence to standard precautions, appropriate isolation protocols, and targeted prophylaxis for high-risk individuals during periods of increased transmission. Further studies are needed to optimize PJP prophylaxis for KTRs with severe lymphopenia.