Center-Specific Variations in Donor Antigen Frequency: Does the OPTN cPRA Calculator Apply to Your Center?

PurposeThe calculated panel reactive antibody (cPRA) estimates the likelihood of an HLA-incompatible donor based on a national historical sample of solid organ donors, but does not take into account regional differences in ethnic populations. We hypothesized that the current OPTN (national) cPRA calculator would inaccurately predict the frequency of certain donor HLA antigens at the center-specific level.MethodsAll US thoracic donors for the calendar years 2012-2013 were analyzed for the frequency of A/B/C and DQ antigen frequencies in 5 US cities with widely disparate minority populations, and then compared to each other and to the predictions of the national cPRA calculator.Results10,290 thoracic donors were analyzed, including all donors from Emory University (Atlanta, GA), Baylor University (Dallas, TX), University of California, Los Angeles (UCLA), University of Wisconsin (UW), and University of California, San Francisco. There were significant differences in donor ethnicity among centers for all ethnic groups. (Table 1.) Caucasian donors were most common at UW and least common at UCLA (87% vs. 57%, P=0.0001). African-American donors were most common at Emory and least common at UCLA (36% vs. 8%, P=0.0001). Latino donors were most common at UCLA and least common at Emory (27% vs.1%, P=0.0001) Although the cPRA accurately predicted the actual antigen frequency within 4 percentage points for the total national cohort, it inaccurately predicted the antigen frequency at any specific center by as much as 22%, owing to significant differences in the frequency of 18/63 (29%) antigens among the five centers. (P = 0.0001 to 0.05)ConclusionThe national cPRA calculator is inaccurate at the center-specific level due to wide ethnic variation in donor HLA antigen frequency. Given that the national cPRA calculator may inaccurately estimate the likelihood of an HLA-incompatible donor at any one specific center, moving to a center-specific or regional cPRA profile may be warranted.Table 1Ethnicities of US thoracic organ donors nationally and at 5 US centers.National Cohort(n=10,290)Emory(n=152)Baylor(n=199)UCLA(n=308)Wisconsin(n=130)P-ValueCaucasian7483 (73%)95 (62%)139 (70%)175 (57%)113 (87%)P=0.0001Latino811 (8%)1 (1%)11 (6%)84 (27%)2 (2%)P=0.0001Asian281 (3%)1 (1%)2 (1%)21 (7%)0 (0%)P=0.0001African American1593 (15%)55 (36%)45 (23%)25 (8%)14 (11%)P=0.0001 Open table in a new tab PurposeThe calculated panel reactive antibody (cPRA) estimates the likelihood of an HLA-incompatible donor based on a national historical sample of solid organ donors, but does not take into account regional differences in ethnic populations. We hypothesized that the current OPTN (national) cPRA calculator would inaccurately predict the frequency of certain donor HLA antigens at the center-specific level. The calculated panel reactive antibody (cPRA) estimates the likelihood of an HLA-incompatible donor based on a national historical sample of solid organ donors, but does not take into account regional differences in ethnic populations. We hypothesized that the current OPTN (national) cPRA calculator would inaccurately predict the frequency of certain donor HLA antigens at the center-specific level. MethodsAll US thoracic donors for the calendar years 2012-2013 were analyzed for the frequency of A/B/C and DQ antigen frequencies in 5 US cities with widely disparate minority populations, and then compared to each other and to the predictions of the national cPRA calculator. All US thoracic donors for the calendar years 2012-2013 were analyzed for the frequency of A/B/C and DQ antigen frequencies in 5 US cities with widely disparate minority populations, and then compared to each other and to the predictions of the national cPRA calculator. Results10,290 thoracic donors were analyzed, including all donors from Emory University (Atlanta, GA), Baylor University (Dallas, TX), University of California, Los Angeles (UCLA), University of Wisconsin (UW), and University of California, San Francisco. There were significant differences in donor ethnicity among centers for all ethnic groups. (Table 1.) Caucasian donors were most common at UW and least common at UCLA (87% vs. 57%, P=0.0001). African-American donors were most common at Emory and least common at UCLA (36% vs. 8%, P=0.0001). Latino donors were most common at UCLA and least common at Emory (27% vs.1%, P=0.0001) Although the cPRA accurately predicted the actual antigen frequency within 4 percentage points for the total national cohort, it inaccurately predicted the antigen frequency at any specific center by as much as 22%, owing to significant differences in the frequency of 18/63 (29%) antigens among the five centers. (P = 0.0001 to 0.05) 10,290 thoracic donors were analyzed, including all donors from Emory University (Atlanta, GA), Baylor University (Dallas, TX), University of California, Los Angeles (UCLA), University of Wisconsin (UW), and University of California, San Francisco. There were significant differences in donor ethnicity among centers for all ethnic groups. (Table 1.) Caucasian donors were most common at UW and least common at UCLA (87% vs. 57%, P=0.0001). African-American donors were most common at Emory and least common at UCLA (36% vs. 8%, P=0.0001). Latino donors were most common at UCLA and least common at Emory (27% vs.1%, P=0.0001) Although the cPRA accurately predicted the actual antigen frequency within 4 percentage points for the total national cohort, it inaccurately predicted the antigen frequency at any specific center by as much as 22%, owing to significant differences in the frequency of 18/63 (29%) antigens among the five centers. (P = 0.0001 to 0.05) ConclusionThe national cPRA calculator is inaccurate at the center-specific level due to wide ethnic variation in donor HLA antigen frequency. Given that the national cPRA calculator may inaccurately estimate the likelihood of an HLA-incompatible donor at any one specific center, moving to a center-specific or regional cPRA profile may be warranted.Table 1Ethnicities of US thoracic organ donors nationally and at 5 US centers.National Cohort(n=10,290)Emory(n=152)Baylor(n=199)UCLA(n=308)Wisconsin(n=130)P-ValueCaucasian7483 (73%)95 (62%)139 (70%)175 (57%)113 (87%)P=0.0001Latino811 (8%)1 (1%)11 (6%)84 (27%)2 (2%)P=0.0001Asian281 (3%)1 (1%)2 (1%)21 (7%)0 (0%)P=0.0001African American1593 (15%)55 (36%)45 (23%)25 (8%)14 (11%)P=0.0001 Open table in a new tab The national cPRA calculator is inaccurate at the center-specific level due to wide ethnic variation in donor HLA antigen frequency. Given that the national cPRA calculator may inaccurately estimate the likelihood of an HLA-incompatible donor at any one specific center, moving to a center-specific or regional cPRA profile may be warranted.