SCCRIP and SAC participants analyzed for genetic associations with acute VOP
| Variable . | SCCRIP (N = 327) . | SAC (N = 175) . | P . | SCCRIP . | ||
|---|---|---|---|---|---|---|
| Female (N = 159) . | Male (N = 168) . | P . | ||||
| Sex | .85 | ND | ||||
| Female (N, %) | 159 (48.6) | 83 (47.4) | 159 (100) | 0 (0) | ||
| Male (N, %) | 168 (51.4) | 92 (52.6) | 0 (0) | 168 (100) | ||
| On HU therapy* | <.0001 | .51 | ||||
| Never (N, %) | 185 (56.6) | 148 (84.6) | 93 (58.5) | 92 (54.8) | ||
| Ever (N, %) | 142 (43.4) | 27 (15.4) | 66 (41.5) | 76 (45.2) | ||
| HU initiation age (y) (mean, SD) | 2.7 (1.5) | 8.3 (1.6) | <.0001 | 2.6 (1.6) | 2.8 (1.3) | .17 |
| Time on HU (mean, SD) | 2.8 (1.3) | 2.3 (1.6) | .08 | 2.8 (1.5) | 2.8 (1.1) | .86 |
| On chronic transfusion therapy* | ND | .04 | ||||
| Never (N, %) | 281 (85.9) | ND | 130 (81.8) | 151 (89.9) | ||
| Ever (N, %) | 46 (14.1) | ND | 29 (18.2) | 17 (10.1) | ||
| −α3.7 deletion | .35† | |||||
| αα/αα (N, %) | 219 (67.0) | ND | 111 (69.8) | 108 (64.3) | ||
| −α3.7α/αα (N, %) | 95 (29.0) | ND | 38 (23.9) | 57 (33.9) | ||
| −α3.7α/−α3.7α (N, %) | 13 (4.0) | ND | 10 (6.3) | 3 (1.8) | ||
| Genotypes determined by WGS | .24 | .22 | ||||
| HbSS (N, %) | 316 (96.6) | 165 (94.3) | 156 (98.1) | 160 (95.2) | ||
| HbSβ0 thalassemia (N, %) | 11 (3.4) | 10 (5.7) | 3 (1.9) | 8 (4.8) | ||
| Age in years‡ (mean, SD) | 5.8 (0.7) | 10.8 (0.7) | <.0001 | 5.8 (0.7) | 5.8 (0.6) | .82 |
| VOP event rate (events/100 person-years, %) | 12.5 (26.3) | 53.2 (56.6) | <.0001 | 11.2 (22.8) | 13.7 (29.3) | .81 |
| Variable . | SCCRIP (N = 327) . | SAC (N = 175) . | P . | SCCRIP . | ||
|---|---|---|---|---|---|---|
| Female (N = 159) . | Male (N = 168) . | P . | ||||
| Sex | .85 | ND | ||||
| Female (N, %) | 159 (48.6) | 83 (47.4) | 159 (100) | 0 (0) | ||
| Male (N, %) | 168 (51.4) | 92 (52.6) | 0 (0) | 168 (100) | ||
| On HU therapy* | <.0001 | .51 | ||||
| Never (N, %) | 185 (56.6) | 148 (84.6) | 93 (58.5) | 92 (54.8) | ||
| Ever (N, %) | 142 (43.4) | 27 (15.4) | 66 (41.5) | 76 (45.2) | ||
| HU initiation age (y) (mean, SD) | 2.7 (1.5) | 8.3 (1.6) | <.0001 | 2.6 (1.6) | 2.8 (1.3) | .17 |
| Time on HU (mean, SD) | 2.8 (1.3) | 2.3 (1.6) | .08 | 2.8 (1.5) | 2.8 (1.1) | .86 |
| On chronic transfusion therapy* | ND | .04 | ||||
| Never (N, %) | 281 (85.9) | ND | 130 (81.8) | 151 (89.9) | ||
| Ever (N, %) | 46 (14.1) | ND | 29 (18.2) | 17 (10.1) | ||
| −α3.7 deletion | .35† | |||||
| αα/αα (N, %) | 219 (67.0) | ND | 111 (69.8) | 108 (64.3) | ||
| −α3.7α/αα (N, %) | 95 (29.0) | ND | 38 (23.9) | 57 (33.9) | ||
| −α3.7α/−α3.7α (N, %) | 13 (4.0) | ND | 10 (6.3) | 3 (1.8) | ||
| Genotypes determined by WGS | .24 | .22 | ||||
| HbSS (N, %) | 316 (96.6) | 165 (94.3) | 156 (98.1) | 160 (95.2) | ||
| HbSβ0 thalassemia (N, %) | 11 (3.4) | 10 (5.7) | 3 (1.9) | 8 (4.8) | ||
| Age in years‡ (mean, SD) | 5.8 (0.7) | 10.8 (0.7) | <.0001 | 5.8 (0.7) | 5.8 (0.6) | .82 |
| VOP event rate (events/100 person-years, %) | 12.5 (26.3) | 53.2 (56.6) | <.0001 | 11.2 (22.8) | 13.7 (29.3) | .81 |
P values in bold represent statistically significant associations (P < .05). Fisher’s exact test was used to compare sex, HU therapy, chronic transfusion therapy, the −α3.7 deletion, and SCD genotype between SCCRIP and SAC participants and between male and female participants in the SCCRIP cohort. The Wilcoxon rank-sum test was used to compare HU initiation age, time on HU, age in years, and VOP event rate between the 2 groups, as listed above. HU, hydroxyurea; ND, not determined; SD, standard deviation.
Hydroxyurea therapy or chronic transfusion therapy administered at any time up to 6 years of age for SCCRIP participants or up to 11 years of age for SAC participants.
P value was calculated based on a 2 × 2 contingency table of the number of participants with αα/αα vs −α3.7α/αα or −α3.7α/−α3.7α.
Age at last follow-up or censored at 6 years of age for SCCRIP participants or at 11 years of age for SAC participants.