Panel reactive antibody (PRA) test has been considered as a routine assessment of sensitization to HLA antigens in kidney transplant candidates. This study was to investigate the effect of risk factors and the time of blood sampling on PRA test.
A total of 111 patients at two dialysis centers in Tehran were enrolled in the study and tested for PRA levels before and after dialysis sessions. History of potential sensitizing events of the patients was recorded through interview. Recent administration of agents affecting PRA such as lovastatin was an excluded criterion.
Mean age of the patients was 56.39±16.48 years. Among 106 patients, PRA before dialysis session was significantly lower than that after dialysis (p=0.000). However, no difference was seen when divided into groups of negative/positive (PRA<10% as negative) and high/low (PRA<60% as low). In 98 patients with no history of drug administration for decreasing PRA, only age and kidney transplant history were correlated with PRA level (r=0.246, p=0.014 and p=0.000, respectively). Also, patients older than 50 had lower PRA levels (p=0.018). Using multivariate analysis, only previous transplantation was associated with higher PRA levels (p=0.000) and positive (>10%) PRA (p=0.03). History of pregnancy and transfusion, dialysis duration, gender, donor relation and kidney allograft duration were not associated with PRA. Many factors which can expose patients to HLA antigens are introduced as sensitizing factors; however, it seems that PRA level is not always predictable by such conditions. Furthermore, dialysis as a confounding procedure impacts on PRA results; thus, when to take blood sample is a crucial question to answer.