Predictors of false-positive and invalid results in postmortem blood testing of tissue donors: a case-control study

Postmortem blood screening for infectious diseases is crucial for safe tissue transplantation. However, false-positive and invalid results occur more often than in living donors, potentially leading to unnecessary graft rejection, based on the acceptance criteria of the Dutch Transplant Foundation. This study aimed to identify factors associated with unreliable postmortem test outcomes. A matched case-control study was conducted using data from Dutch tissue donors screened between 2018 and 2023. Cases included 174 donors with false-positive or invalid results, and controls included 460 donors with reliable results. Logistic regression assessed associations between test unreliability and donor factors, including age, body mass index (BMI), sepsis, and malignancy, and procedural factors, including postmortem interval (PMI) and method of blood collection. Prolonged PMI and pathologist-collected samples with delayed processing were significantly associated with unreliable test results. Each additional hour of PMI increased the odds by 10 percent (adjusted OR 1.10, 95% CI: 1.06-1.13, p < 0.001). Blood collection prior autopsy showed over fourfold higher odds of an unreliable result (adjusted OR 4.54, 95% CI: 1.61-13.9, p = 0.005). Donor-related characteristics showed no significant associations. Unreliable postmortem test results are primarily associated with procedural factors. Reducing the PMI and standardizing sampling methods may improve test accuracy.