Developmental delay in infants and toddlers with sickle cell disease: a systematic review.

Only 10 studies, and 9 of them had fewer than 100 participants. That is a thin evidence base for a question about how common delay is. The studies used different tests and looked at different domains, so the authors could not combine the results. The 17.5% to 50% figure is a range across studies, not one pooled estimate. In three instances two publications reported the same cohort of children, so the same children are counted more than once. The authors call this a considerable limitation. In most included studies the person doing the developmental assessment could not be blinded to the child's sickle cell diagnosis, which can bias scores. The conversion used to make newer Bayley-III scores equivalent to the older BSID-II index is contested. One large study of 193 children also excluded children with substantial developmental delays. Both would push the reported rate of delay downwards, and the authors say the true rate of cognitive delay may be higher than they found. All included studies came from the USA or UK, and most participants were African American or Afro-Caribbean, often from lower-income households. The findings may not transfer to other populations or health systems. Two studies were at high risk of bias for selective reporting of outcomes and one for small sample size. No study used a caregiver-report screening measure, even though current screening recommendations favour them. Only one study tested any intervention for developmental delay, and it was a home-based caregiver education programme. The review says nothing about whether therapy changes these children's outcomes.

No funding or competing-interest statement appears in the text supplied for this summary, so it is not possible to say who paid for the review or what the authors declared.

Do not read this as evidence that early intervention or any therapy improves outcomes for these children. Only one of the ten studies tested an intervention, and it was home-based caregiver education; the review found no trials of developmental therapy, and the authors say screening alone will not improve outcomes. The 17.5% to 50% range is also not a reliable count of how many children are affected, since it comes from small studies that partly repeat the same children.