Anorexia nervosa among young children in the UK and Ireland on the up

The annual number of new cases of anorexia nervosa among 8 to 12 year olds in the UK and Ireland is around double that of a previous estimate in 2006, indicates research published in the online journal BMJ Open.

In 2006, the incidence rate of anorexia among 8-12 year olds treated in hospital/specialist clinics in the UK was approximately 1.5/100,000 young people, or with the inclusion of 'other eating disorders' that may now be diagnosed as anorexia nervosa, 2.1/100,000.

This latest analysis indicates that the figure for children in this age bracket is 3.2/100,000.

This suggests "that incidence rates for younger children have increased over time," conclude the researchers, who set out to update available estimates of the annual number of new cases of anorexia in the UK and Ireland among children and teens.

Current estimates are at least 10 years old and mostly derived from GP records, rather than hospital/specialist clinic, services, which are likely to be a more reliable source of information on how many children and teens have the condition, say the researchers.

They therefore drew on monthly records, submitted by specialist psychiatrists to the Child and Adolescent Psychiatry Surveillance System in the UK and Ireland for a period of eight months in 2015.

The data, which cover 8 to 17 year olds, diagnosed for the first time with anorexia nervosa, were used to calculate the annual incidence rate—the rate of new cases per 100,000 among those in this age bracket.

During the eight months, 305 new cases were diagnosed, most of them in young women (91%), from England (70%), and of white ethnicity (92%).

Based on these figures, the researchers calculated an annual incidence rate of 26/100,000 for girls and 2/100,000 for boys, with an overall rate of 14 new cases for every 100,000 children and teens aged 8 to 17.

The rate of new cases rose steadily with age, peaking at the age of 16, with a substantial drop by the age of 17. For girls, this peak occurred at the age of 15, compared with 16 for boys. But rates fell by at least half by the age of 17 for both sexes.

Comparable figures for 8-12 year olds were 3.2/100,000, overall, with rates of 4/100,000 for 11 year olds, and 12/100,000 for 12 year olds, the calculations indicated.

"Future research should explore the development of earlier interventions, given evidence of an increase in incidence in young children, suggesting that onset of anorexia nervosa may be starting earlier for some young people than suggested by previous research," write the researchers.

This is an observational study, and as such, can't establish cause. And missing data, including cases where young people were seen only by a GP, or didn't come to the attention of services, may have affected the accuracy of the calculations.

But this is a large, nationally representative study, based on confirmed diagnoses, and its findings may therefore also be applicable to other high-income countries, suggest the researchers.

While firm conclusions about changes in the rate of new cases over time can't be drawn due to the lack of existing secondary care data, and differences in the way data have been collected, "service providers and commissioners should consider the evidence to suggest an increase in the number of new cases in younger children," they add.