Call for universal CAH screening

An analysis of 100 years of epidemiological data from Sweden has shown that neonatal screening for congenital adrenal hyperplasia (CAH) is as effective at improving survival in boys as it is in girls.

The findings contradict widespread belief that diagnosis of the severe salt-wasting form of the disease was more likely to be missed in boys without screening, but in fact, girls were equally likely to be missed by physical examination alone.

Commentators say that the study results support the introduction of universal CAH screening, which is currently lacking in some countries, including Australia and the UK.

Sebastian Gidlöf (Karolinska University Hospital, Stockholm, Sweden) and colleagues used data from 606 patients with CAH due to 21-hydroxylase deficiency diagnosed between 1910 and 2011, including 231 who were identified by the Swedish neonatal screening program introduced in 1986.

Over the study period, the apparent incidence of CAH rose dramatically, with 96% of the patients being diagnosed after the introduction of glucocorticoid treatment in 1950, the authors report in The Lancet Diabetes and Endocrinology. And, during the 1960s and 1970s the incidence rose from one in 37,000 to the present day incidence of one in 8800. The authors say there is no reason to believe that the actual prevalence of CAH has changed over time and that the increase observed is likely due to improved physician awareness following the arrival of an effective treatment.

The overall ratio of females to males in the study population was 25 to one. It has previously been suggested that the female preponderance among patients diagnosed with CAH is due to girls being more easily detected because of virilized genitalia at birth. However, Gidlöf and colleagues calculated that before 1970, five to 10 patients died every year from undiagnosed salt-wasting form of the disease, with males and females similarly affected.

Additionally, they found that males and females were equally represented among patients identified through neonatal screening and that the female preponderance in their study was therefore from non-classic CAH, which is diagnosed more often in women than men.

In a linked comment, Bridget Wilcken (University of Sydney, New South Wales, Australia) said that more research is still needed into the disease.

"It is surprising that after 30 years of neonatal screening worldwide there is still a need for additional screening data and, importantly, follow-up, so that the benefits of screening can be accurately assessed, and screening efficiency can be maximized."

She adds: "There is little doubt that screening for the disorder fulfils the essential criteria for screening - it is, after all, a potentially lethal disorder."

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