Severe Undernutrition Predicts Adverse Outcomes in Transplant Norovirus Infection

Background Norovirus infection is a frequent cause of diarrhea after kidney transplantation, with heterogeneous clinical presentations. Without specific antiviral treatment, management mainly relies on immunosuppression minimization. However, prognostic factors for mortality and graft loss remain poorly defined. Methods We performed a multicenter retrospective study of kidney transplant recipients (KTRs) with norovirus infection between January 2017 and December 2022. A multicentric matched control group of 96 KTRs with non-norovirus diarrhea was included for comparative nutritional analysis. Variables were collected at baseline, diagnosis, and follow-up, and included recipient/donor characteristics, infection features, immunosuppressive adjustment, nutritional status, and outcomes. Factors associated with mortality and graft loss were analyzed using univariate and multivariate models. Results One-hundred fifty-nine KTRs with norovirus infection were followed for a median of 2.7 years. At diagnosis, the norovirus group showed a significantly greater decrease in BMI compared to controls (−5.5% vs. −1.5%, p<0.0001), along with a higher prevalence of severe undernutrition (29.6% vs. 10.4%, p=0.0010). Mortality (7.3 events/100 person-years) and graft loss (4.4 events/100 person-years) increased stepwise with the severity of undernutrition. Severe undernutrition at diagnosis was independently associated with both mortality (HR=3.87 [1.34–11.21], p=0.0126) and graft loss (HR=2.96 [1.02–8.60], p=0.0468), along with age, diabetes, and baseline creatininemia. Despite immunosuppressive minimization, no significant improvement in survival outcomes was observed. Conclusions Severe undernutrition at diagnosis is a major independent predictor of adverse outcomes in KTRs with norovirus infection. Therefore, we recommend close monitoring of nutritional parameters and active nutrition strategies to prevent severe undernutrition in this high-risk population.