By Danny Kucharsky
MONTREAL -- September 16, 2008 -- The vast majority of women who recover from anorexia nervosa after being ill for more than 5 years do not have low bone mineral density (BMD), according to study results presented here at the American Society for Bone and Mineral Research (ASBMR) 30th Annual Meeting.
While decreased bone mass is a well established consequence of anorexia nervosa, there is contradictory evidence as to whether the deficits in bone mass can be recovered with recovery from anorexia nervosa, noted Esther Waugh, BScPT, MSca, University of Toronto and Women's College Hospital, Toronto, Ontario, speaking here on September 12 at a plenary poster presentation.
"We were interested in looking at prevention of osteoporosis in young people, and wanted to focus on a group that was most at risk, to see if they recovered or whether they were at risk [in the] long term," said Ms. Waugh.
"Most previous studies have had very small sample size -- 20 to 30 people -- and a lot were done on adolescents, so they didn't have time to recover for very long," Ms. Waugh noted. As well, in most previous studies "there just wasn't enough time for normalisation of bone to have occurred. [Patients] need at least 3 years of recovery before bone levels out."
To achieve a larger sample size, the investigators recruited 190 adult inpatient women aged 40 years and younger who had been admitted for inpatient treatment for anorexia nervosa over a 10-year period. These subjects were compared to a control group of 514 healthy, premenopausal women with no histories of eating disorders.
Participants were measured for a dual energy x-ray absorptiometry densitometry bone scan, and a thorough lifetime history was conducted, which included everything from exercise to menstrual history. Participants were considered recovered if they had achieved a body mass index of ≥18.5 kg/m▓ and resumed menstruation for 1 year or more.
A total of 8.8% of patients with anorexia nervosa who had recovered and had been ill for less than 5 years (n = 57) had low BMD, compared with 6.8% of controls. By contrast, 20% of patients with anorexia nervosa who had recovered and had been ill for 5 years or greater (n = 20) had low BMD.
For patients who remained ill for less than 5 years (n = 45), 35.6% had low BMD, while among those ill for 5 years or more (n = 68), 49.2% had low BMD. The study concluded that duration of illness was the only illness characteristic independently associated with BMD.
"The number one surprise was that [anorexia nervosa patients] recover," Ms. Waugh stated, "and the effect and duration of illness is not huge once they recover. [Of those who] recovered after being ill for 5 years, only 20% had low bone density."
"I was not expecting to see such dramatic results," Ms. Waugh concluded.
[Presentation title: Bone Mass Recovers in Young Women With Anorexia Nervosa Who Are Both Weight and Menstrual Recovered. Abstract F339]
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