Demographic and laboratory characteristics of discovery and replication cohorts included in genome-wide association study
| Characteristic . | Functional assay-positive* . | Antibody-positive (functional assay-negative) controls*,† . | Antibody-negative controls*,† . | P value‡ . |
|---|---|---|---|---|
| Discovery cohort | ||||
| Total (n) | 1269 | 1131 | 1766 | — |
| Female, n (%) | 535 (42.2) | 412 (36.4) | 697 (39.5) | .016 |
| Age (yr) | 66.5 (13.6) | 64.7 (15.6) | 67.3 (13.5) | .0004 |
| IgG (OD)† | 1.79 (0.71) | 0.90 (0.40) | 0.17 (0.12) | <.0001 |
| IgA (OD)† | 0.74 (0.60) | 0.50 (0.46) | 0.21 (0.24) | <.0001 |
| IgM (OD)† | 0.70 (0.43) | 0.66 (0.42) | 0.35 (0.25) | <.0001 |
| Ancestry, n (%)§ | ||||
| European | 1252 (98.7) | 1108 (98.0) | 1735 (98.2) | .408 |
| African | 2 (0.2) | 2 (0.2) | 3 (0.2) | 1.00 |
| Asian | 1 (0.1) | 1 (0.1) | 2 (0.1) | 1.00 |
| Admixed | 14 (1.1) | 20 (1.8) | 26 (1.5) | .395 |
| Ancestral proportion (%)§ | ||||
| European | 0.988 | 0.984 | 0.986 | .233 |
| African | 0.006 | 0.008 | 0.007 | .236 |
| Asian | 0.006 | 0.008 | 0.007 | .348 |
| Replication cohort | ||||
| Total (n) | 177 | 258 | 351 | — |
| Female, n (%) | 98 (55.7) | 90 (34.9) | 89 (25.4) | <.0001 |
| Age (yr) | 67.2 (14.0) | 67.1 (13.0) | 69.8 (12.1) | .014 |
| Platelet count prior to heparin (×103/µL) | 227.3 (63.3) | 221.8 (63.3) | 207.5 (51.0) | .004 |
| PF4/heparin antibodies (OD)† | 2.47 (0.72) | 1.17 (0.56) | 0.21 (0.07) | <.001 |
| Ancestry, n (%)§ | ||||
| European | 170 (96.1) | 250 (96.9) | 341 (97.2) | .782 |
| African | 3 (1.7) | 2 (0.8) | 1 (0.3) | .173 |
| Asian | 1 (0.6) | 0 (0) | 1 (0.3) | .707 |
| Admixed | 3 (1.7) | 6 (2.3) | 8 (2.3) | .904 |
| Ancestral proportion (%)§ | ||||
| European | 0.962 | 0.977 | 0.980 | .625 |
| African | 0.026 | 0.018 | 0.013 | .629 |
| Asian | 0.012 | 0.005 | 0.007 | .866 |
| Characteristic . | Functional assay-positive* . | Antibody-positive (functional assay-negative) controls*,† . | Antibody-negative controls*,† . | P value‡ . |
|---|---|---|---|---|
| Discovery cohort | ||||
| Total (n) | 1269 | 1131 | 1766 | — |
| Female, n (%) | 535 (42.2) | 412 (36.4) | 697 (39.5) | .016 |
| Age (yr) | 66.5 (13.6) | 64.7 (15.6) | 67.3 (13.5) | .0004 |
| IgG (OD)† | 1.79 (0.71) | 0.90 (0.40) | 0.17 (0.12) | <.0001 |
| IgA (OD)† | 0.74 (0.60) | 0.50 (0.46) | 0.21 (0.24) | <.0001 |
| IgM (OD)† | 0.70 (0.43) | 0.66 (0.42) | 0.35 (0.25) | <.0001 |
| Ancestry, n (%)§ | ||||
| European | 1252 (98.7) | 1108 (98.0) | 1735 (98.2) | .408 |
| African | 2 (0.2) | 2 (0.2) | 3 (0.2) | 1.00 |
| Asian | 1 (0.1) | 1 (0.1) | 2 (0.1) | 1.00 |
| Admixed | 14 (1.1) | 20 (1.8) | 26 (1.5) | .395 |
| Ancestral proportion (%)§ | ||||
| European | 0.988 | 0.984 | 0.986 | .233 |
| African | 0.006 | 0.008 | 0.007 | .236 |
| Asian | 0.006 | 0.008 | 0.007 | .348 |
| Replication cohort | ||||
| Total (n) | 177 | 258 | 351 | — |
| Female, n (%) | 98 (55.7) | 90 (34.9) | 89 (25.4) | <.0001 |
| Age (yr) | 67.2 (14.0) | 67.1 (13.0) | 69.8 (12.1) | .014 |
| Platelet count prior to heparin (×103/µL) | 227.3 (63.3) | 221.8 (63.3) | 207.5 (51.0) | .004 |
| PF4/heparin antibodies (OD)† | 2.47 (0.72) | 1.17 (0.56) | 0.21 (0.07) | <.001 |
| Ancestry, n (%)§ | ||||
| European | 170 (96.1) | 250 (96.9) | 341 (97.2) | .782 |
| African | 3 (1.7) | 2 (0.8) | 1 (0.3) | .173 |
| Asian | 1 (0.6) | 0 (0) | 1 (0.3) | .707 |
| Admixed | 3 (1.7) | 6 (2.3) | 8 (2.3) | .904 |
| Ancestral proportion (%)§ | ||||
| European | 0.962 | 0.977 | 0.980 | .625 |
| African | 0.026 | 0.018 | 0.013 | .629 |
| Asian | 0.012 | 0.005 | 0.007 | .866 |
OD, optical density.
Values represent mean (standard deviation) unless otherwise specified.
Functional assay-positive status was determined using the HIPA test in the discovery cohort and the serotonin release assay in the replication cohort.
PF4/heparin antibody levels were determined using ELISA in both discovery and replication cohorts.
P values for comparison across 3 groups were generated using Fisher’s exact test for dichotomous variables and Kruskal-Wallis test for continuous variables.
Ancestral proportions were generated using ancestry-informative markers from genome-wide arrays input into STRUCTURE with HapMap reference panels. Individuals were considered to have European, African, or Asian ancestry if relevant ancestral proportions were ≥80 percent. Otherwise, individuals were considered admixed since patient-reported race/ethnicity data were not available.