Implications for patients waiting for a kidney transplant of using the calculated panel reactive antibody (cPRA)

Introduction: Kidney transplant improves survival even in highly-sensitized(HS) patients. To overcome their disadvantage in accessing transplantation, those with high Complement Dependent Cytotoxic PRA (CDC-PRA) receive additional points during allocation. Whether this strategy reaches all HS patients and how long they wait for a transplant is largely undetermined. Methods: Patients on our unit’s active wait-list for kidney transplantation in the year 2014 were analyzed. CDC-PRA and calculated PRA (cPRA) were recorded. To obtain cPRA, antibodies in the last serum available specific for HLA-A,-B or -DR with an intensity &gt; 1000 MFI were considered. Results: The cPRA values in the population (N=551) were 0% (N=312), 1-79% (N=118) and ≥ 80% (22%; N=121). Among these groups, the proportion of women (29.5, 55.9 and 61.2%, P<0.001), prior sensitizing events (43.3, 80.5 and 96.7%, P<0.001) and time on dialysis (median of 3.9, 4.1 and 6.0 years, P<0.001) increased with cPRA, respectively. In most of those with a cPRA ≥ 80%, the CDC-PRA raised no suspicion of HS status (median 0%, P25-75 0-8%) and only 35 (28.9%) or 12 patients (9.9%) had a CDC-PRA in the peak serum higher than 50 or 80%, respectively (cut-offs needed to obtain additional points during allocation). HS patients by cPRA corresponded to 71% vs 15% of patients waiting for ≥ or <8 years, respectively (P<0.001). Even after exclusion of patients with a CDC-PRA above 50%, this disproportionate representation remained (58% versus 13%, P<0.001). Conclusion: HS patients as measured by cPRA remained longer on the wait-list, both in the primary analysis and when excluding those with a CDC-PRA&gt; 50%. Moreover, only 30% of HS by cPRA patients received the extra points designed to improve their transplantability. We consider that both CDC-PRA and cPRA should be taken into account when defining HS status