Table 2.
Risk factors for inhibitor development in UK PUPs
| All inhibitor development | High-titer inhibitor development | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| n | Events n (%) | Unadjusted HR (95% CI) | P | Adjusted HR (95% CI) | P | Events n (%) | Unadjusted HR (95% CI) | P | Adjusted HR (95% CI) | P | |
| Ethnicity | |||||||||||
| White | 354 | 95 (26.8) | 1.00 | 1.00 | 42 (11.9) | 1.00 | 1.00 | ||||
| Nonwhite | 53 | 23 (43.4) | 1.76 (1.12-2.78) | .02 | 1.59 (0.96-2.66) | .07 | 18 (34.0) | 3.09 (1.78-5.38) | <.005 | 2.91 (1.55-5.45) | <.005 |
| Missing | 0 | ||||||||||
| Intensive treatment at first exposure | |||||||||||
| Yes | 56 | 28 (50.0) | 2.38 (1.56-3.65) | <.005 | 2.01 (1.22-3.31) | .01 | 13 (23.2) | 2.14 (1.16-3.97) | .02 | 0.90 (0.62-1.32) | .60 |
| No | 343 | 87 (25.4) | 1.00 | 1.00 | 45 (13.1) | 1.00 | 1.00 | ||||
| Missing | 8 | 3 (37.5) | 2 (25.0) | ||||||||
| Genotype | |||||||||||
| High risk | 244 | 95 (38.9) | 3.11 (1.90-5.09) | <.005 | 2.35 (1.41-3.90) | <.005 | 48 (19.7) | 3.29 (1.62-6.71) | <.005 | 2.57 (1.25-5.26) | .01 |
| Low risk | 133 | 19 (14.3) | 1.00 | 1.00 | 9 (6.8) | 1.00 | 1.00 | ||||
| Missing | 30 | 4 (13.3) | 3 (10.0) | ||||||||
| FH of haemophilia | |||||||||||
| Yes | 232 | 63 (27.2) | 0.80 (0.56-1.16) | .24 | 0.82 (0.54-1.25) | .36 | 37 (16.0) | 1.13 (0.67-1.90) | .65 | 0.89 (0.48-1.64) | .71 |
| No | 174 | 55 (31.6) | 1.00 | 1.00 | 23 (13.2) | 1.00 | 1.00 | ||||
| Missing | 1 | 0 (0.0) | 0 (0.0) | ||||||||
| FH of an inhibitor | |||||||||||
| Yes | 41 | 17 (41.5) | 1.97 (1.13-3.44) 1.00 | .02 | 1.07 (0.55-2.09) 1.00 | .84 | 13 (31.7) | 2.86 (1.45-5.62) 1.00 | <.005 | 2.04 (0.87-4.74) | .10 |
| No | 190 | 46 (24.2) | 24 (12.6) | 1.00 | |||||||
| Missing | 1 | 0 (0.0) | 0 (0.0) | ||||||||
| Age at first exposure, y1 | 0.81 (0.64-1.04) | .10 | 0.90 (0.69-1.18) | .43 | 0.82 (0.58-1.15) | .25 | 0.90 (0.62-1.32) | .60 | |||
Missing data were imputed using multiple logistic regression methods. Risk associated with each additional year.1 Data are adjusted for ethnic group, age at first exposure to factor VIII, year of first factor VIII exposure, center of first treatment, FH of hemophilia, FH of inhibitors, intensive treatment at first treatment, and FVIII genotype (adjusted for high/low risk as defined in “Methods”).