Duchenne muscular dystrophy: relevant paper was not included

EDITOR—Dorling and Salt describe an evidence based approach to the assessment of a boy with locomotor developmental delay manifesting as late walking.1 In their literature search they have missed a relevant paper.2 This paper was probably not identified by their literature search as it is incorrectly indexed in Medline as a case report rather than a prospective cohort study. The fallibility of electronic databases is well known, and because of this previous authors have highlighted the need for expert help when performing a systematic review.3

The paper evaluates the community screening of a cohort of boys aged 18 months for late walking and Duchenne muscular dystrophy. Of the population of 25 299 boys, 19 986 (79%) were screened for late walking at 18 months, of whom 338 (1.7%) were not walking. Altogether 205 boys (75%) had creatine kinase concentrations measured on fingerprick blood testing, and two cases of Duchenne muscular dystrophy were identified. This programme provided further justification to screen boys who were late walking for Duchenne muscular dystrophy with a number needed to screen of only 100.

The issue of community screening for Duchenne muscular dystrophy is complex. Because the uptake of primary care developmental surveillance (which is not screening in its true sense) is not complete, some children who are not walking at 18 months will not be identified. Not all surveillance guidelines in primary care recommend referral for specialist assessment of all children who are late walking at 18 months. There are further complex issues relating to consent for the blood test. In addition, as 50% of boys with Duchenne muscular dystrophy are walking at 18 months, such a programme would at best identify half of the cases. Therefore such a community screening programme for Duchenne muscular dystrophy was not justifiable and the recommendation was for opportunistic screening of those late walking boys at 18 months who are identified.

We also disagree with Dorling and Salt that this information is not available in textbooks. Aicardi says in a standard text that, owing to the difficulty in early recognition, creatine kinase concentration should always be systematically determined in children who do not walk by 18 months of age.4

Dorling and Salt do, however, highlight the important issue of late diagnosis of Duchenne muscular dystrophy. Until screening of newborn infants is introduced on a wider scale we will need to rely on the early clinical recognition of the condition by general practitioners, paediatricians, and orthopaedic surgeons. This should also include wider recognition that in young boys with Duchenne muscular dystrophy language delay is often a more notable feature.5