Table 1. Patient characteristics.
| Demographic variables | Summary statistic | Observations (N) |
|---|---|---|
| Age [years], mean (SD) | 9·76 (3·86) | 601 |
| Males, n (%) | 325 (54·08) | 601 |
| Survey, n (%) | ||
| 2004/05 | 305 (50·75) | 601 |
| 2009 | 224 (37·27) | |
| 2010 | 72 (11·98) | |
| Laboratory variablesa | ||
| Haemoglobin [g/l], mean (SD) | 74·0 (11·2) | 583 |
| Fetal haemoglobin [%], mean (SD) | 5·23 (3·84) | 533 |
| CBFv | ||
| MCA maximum velocity, left or right, n (%) | ||
| Kenyan non‐SCA criteriab | 601 | |
| Normal | 387 (64·39) | |
| Low [≤43 cm/s or <39·5 cm/s] | 44 (7·32) | |
| High [>141 cm/s or >143·5 cm/s] | 170 (28·29) | |
| STOP criteria | ||
| Normal | 534 (88·85) | |
| Conditional >170 < 200 cm/s | 25 (4·16) | |
| Abnormal ≥200 cm/s | 42 (6·99) | |
| Asymmetry (Vasospasm)c n (%) | ||
| No asymmetry | 317 (54·75) | 579 |
| Mild asymmetry | 104 (17·96) | |
| Moderate asymmetry | 93 (16·06) | |
| Severe asymmetry | 65 (11·23) | |
SD, standard deviation; CBFv, cerebral blood flow velocity; SCA, sickle cell anaemia; STOP, stroke prevention in sickle cell disease; MCA: middle cerebral artery.
a
All laboratory values were assessed within 7 d of the Transcranial Doppler (TCD) measurement, except HbF which if measured under the age of 60 months and not within 7 d of the TCD was not included.
b
Based on values from healthy Kenyan children (mean ± 2 SD)(Newton et al, 1996).
c
Degree of asymmetry is difference in the maximum velocities in the left MCA and right MCA, calculated as a percentage of the lower velocity. Mild = 40–75%, moderate ‐ 75–180%, severe >180%.