Prognostic Factors for Mortality of COVID-19 Infection in Kidney Transplant Recipients in Thailand: A Nationwide Study

ABSTRACT

Purpose: To investigate the mortality risk factors of COVID-19 infection among kidney transplant recipients (KTRs) in Thailand due to data scarcity in Asian populations. Method(s) We analyzed the data from the Thai Transplant Registry which collected data from all transplant centers from March 2020 to November 2021. The outcomes were the mortality rate over time, ICU admission rate and mortality risk factors including patients' demographic data, comorbidities, vaccination, immunosuppression, and laboratory tests. Result(s) Seventy-two KTRs were infected with COVID-19. The mortality rate was 16.7% (12/72) which was highest (6/12) in July 2021 when the B.1.617.2 variant became most dominant strain. All dead patients were deceased donor kidney transplant (DDKT, 100%). 33.3% (24/72) need to be admitted to the ICUs. The mean age of patients in non-survivor group was significantly higher than those in survivor group (53.4 +/- 10.3 vs 44.5 +/- 9.9 years, p=0.006). The underlying diseases including diabetes and hypertension did not increased mortality. However, hypertension significantly increased ICU admission risk (OR 6.8, 95%CI 1.8-30.6). The mean BMI among non-survivor group was similar to survivor group (25.0 +/- 3.9 vs 23.3 +/- 4.5 kg/m2, p=0.23). The transplantation vintage was not different among both groups (73.5 [12.5-180.5] in the non-survivor vs 52.0 [29.0-97.0] months in the survivors p=0.77). Baseline immunosuppressive regimens were not associated with mortality. The non-survivor group had significantly higher baseline serum creatinine (2.87 +/- 2.63 vs 1.68 +/- 0.82 mg/dL, p=0.006). The area under the ROC curve for mortality was 0.62 for neutrophil to lymphocyte ratio (NLR). The NLR of 3.3 showed highest sensitivity (71%) and specificity (53%) in predicting mortality. Higher IL-6 was associated with requiring ICU admission (23.2 [15.4-70.6] vs 10.4 [4.1-24.2], p=0.04). In non-survivor group, 9 (75%) KTRs were unvaccinated and 3 (25%) KTRs were incomplete vaccinated (1 dose of ChAdOx1 nCoV-19 vaccine in 2 KTRs, and 1 dose of CoronaVac vaccine in 1 KTRs). In non-survivor group, most common medical complications were bacterial pneumonia (58.3%) and lifethreatening bleeding (16.7%). Conclusion(s) In Thailand, the mortality rate of COVID-19 infected KTRs was comparable to worldwide reports which was 10-32%. Higher patients' age, DDKT as well as admission serum creatinine and IL-6 were associated with increasing disease severity. Both unvaccinated and not fully vaccinated KTRs were significantly at higher risk of death.