Table 1.
Baseline characteristics of Black patients with a hemoglobin electrophoresis seen between 2005 and 2018 with at least 1 yr of follow-up and three serum creatinine measurements
| Covariate | Normal Hemoglobin Phenotype (N=8968) | Sickle Cell Trait (N=1279) | Sickle Cell Disease (N=254) |
|---|---|---|---|
| Demographics | |||
| Mean age (SD), yr | 36 (±13) | 40 (±15) | 32 (±12) |
| Age ≥65 yr, N (%) | 310 (3) | 94 (7) | 2 (1) |
| Female, N (%) | 7876 (88) | 999 (78) | 133 (52) |
| Median follow-up (IQR), yr | 7.6 (4.1–10.9) | 7.8 (4.0–10.9) | 6.0 (3.0–9.8) |
| Comorbidities, N (%) | |||
| Hypertension | 1814 (20) | 385 (30) | 30 (12) |
| Diabetes mellitus | 1394 (16) | 320 (25) | 24 (9) |
| Cardiovascular disease | 882 (10) | 187 (15) | 71 (28) |
| Hemoglobin electrophoresis indicationsa, N (%) | |||
| Anemia | 3495 (39) | 315 (25) | — |
| Perinatal testing | 4629 (52) | 482 (37) | — |
| Other | 329 (3) | 215 (17) | — |
| Unknown | 515 (6) | 267 (21) | — |
| Medications, N (%) | |||
| Renin-angiotensin-aldosterone inhibitors | 1790 (20) | 368 (29) | 52 (20) |
| Hydroxyurea | 14 (0.2) | 4 (0.3) | 125 (49) |
| Laboratory values | |||
| Mean serum creatinine (SD), mg/dl | 0.8 (±0.3) | 0.9 (±0.3) | 0.8 (±0.5) |
| Mean eGFR (SD), ml/min | 114 (±27) | 104 (±28) | 128 (±36) |
| eGFR categories, N (%) | |||
| ≥60 ml/min | 8681 (97) | 1202 (94) | 240 (94) |
| 30–59 ml/min | 246 (2) | 70 (5) | 9 (4) |
| 15–29 ml/min | 41 (1) | 7 (1) | 5 (2) |
| Mean hemoglobin (SD), g/dl | 12.3 (1.6) | 12.6 (1.7) | 9.9 (2.2) |
| Mean hemoglobin A2 percentage levels (SD) | — | 3.2 (±0.7) | — |
| Hemoglobin F >0.4%, N (%) | — | 299 (25) | — |
| Mean hemoglobin S percentage (SD) | — | 37 (±4.3) | — |
IQR, interquartile range.
a
Indications for hemoglobin electrophoresis in patients with sickle cell disease were all to assess sickle cell disease–modifying treatment response (e.g., follow-up after exchange transfusion to assess sickle hemoglobin levels or to assess fetal hemoglobin levels on hydroxyurea).