Table 1.
Demographic and clinical characteristics of adults with HbSC disease compared with adults with HbSS disease
| Characteristics | HbSC (N = 639) | HbSS (N = 639) | P value∗ |
|---|---|---|---|
| Age, mean (standard deviation) | 30.7 (7.8) | 31.0 (7.8) | .450 |
| Female, n (%) | 387 (60.6) | 387 (60.6) | 1.00 |
| Hemoglobin, g/dL, mean (standard deviation) | 11.1 (1.3) | 8.1 (1.2) | < .001 |
| Disease-modifying therapy, n (%) | |||
| Hydroxyurea | 6 (0.9) | 15 (2.3) | .048 |
| Chronic blood transfusion | 0 (0.0) | 0 (0.0) | 1.00 |
| Number of individuals with only 1 severe complication, n (%) | |||
| Acute pain (≥3 episodes per y) | 54 (8.5) | 126 (19.7) | < .001 |
| ACS | 10 (1.6) | 24 (3.8) | .015 |
| Severe symptomatic chronic anemia | 0 (0.0) | 4 (0.6) | .124†‡ |
| Proportion of individuals with SCD eligible for hydroxyurea using only 1 severe complication (ASH 2014 guidelines), n (%)§ | 64 (10.0) | 154 (24.1) | < .001 |
| Proportion of individuals with SCD eligible for hydroxyurea with 1 or more severe complication (ASH 2014 guidelines), n (%)§ | 67 (10.5) | 168 (26.3) | < .001 |
| Acute pain events per y, n (%) | |||
| 0 | 344 (53.8) | 289 (45.2) | < .001 |
| 1-2 | 238 (37.2) | 212 (33.2) | |
| ≥3 episodes | 57 (8.9) | 138 (21.6) | |
| Pain incidence rate (events per 100 patient-y) (95% CI) | 74.6 (67.9-81.3) | 123.0 (114.4-131.6) | < .001† |
| ACS incidence rate (events per 100 patient-y) (95% CI) | 2.3 (1.2-3.5) | 5.6 (3.8-7.5) | .004† |
| Prevalence of complications among patients, n (%) | |||
| Severe symptomatic chronic anemia, n (%) | 0 (0.0) | 10 (1.6) | .001‡ |
| AVN, n (%) | 49 (7.7) | 61 (9.5) | .231 |
| Cerebrovascular accident/ stroke, n (%) | 3 (0.5) | 7 (1.1) | .204 |
| Priapism, n (%)‖ | 11 (4.4) | 26 (10.3) | .011 |
| Nephropathy, n (%) | 7 (1.1) | 54 (8.5) | < .001 |
| Albuminuria | 0 (0.0) | 54 (100.0) | |
| Painless gross hematuria | 7 (100.0) | 0 (0.0) | |
| Renal papillary necrosis | 7 (100.0) | 0 (0.0) | |
| Proliferative SCD retinopathy, n (%) | 20 (3.1) | 4 (0.6) | < .001 |
| Active chronic leg ulcer, n (%) | 0 (0.0) | 53 (8.3) | < .001 |
| Systemic hypertension, n (%) | 23 (3.6) | 7 (1.1) | .003 |
| Chronic pain, n (%) | 110 (17.2) | 156 (24.4) | .002 |
Severe symptomatic chronic anemia was defined as a drop in the hemoglobin ≥2g/dL below the steady state.
Hypertensive heart disease was defined as systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg after repeated examinations. Patients with documented evidence of taking antihypertensives for at least 2 months were included; however, patients with sickle cell nephropathy who were solely on antihypertensives for their nephropathy were excluded.20
The causes of chronic pain include AVN, osteoarthritis of the knee and elbow joints, spondylosis (both lumbar and cervical), and active chronic leg ulcers.
χ2test for counts and t test for means, unless otherwise noted.
Poisson regression.
Fisher exact test.
Proportion of patients with SCD eligible for hydroxyurea using at least 1 severe complication was considered for patients with multiple severe complications.
The prevalence rate for priapism was calculated using the denominator N = 252 because priapism only occurs in males.