Prevalence and sociodemographic correlates of DSM-5 eating disorders in the Australian population
The Diagnostic and Statistical Manual of Mental Disorders criteria for eating disorders were revised in 2013 [1,2]. In the DSM-IV [1] three eating disorders, anorexia nervosa, bulimia nervosa and binge eating disorder (BED- classified under Eating Disorder not Otherwise Specified (EDNOS)), had specific criteria. People who did not meet criteria but nevertheless had an eating disorder were also classified under EDNOS. EDNOS was, however, the most common of all the syndromes in both the clinic and community [3]. A key aim of the revision was to broaden criteria for bulimia nervosa and anorexia nervosa and include BED as a third, formal diagnosis. For bulimia nervosa and BED the specific change was to reduce frequency of binge eating (and for bulimia nervosa compensatory weight-control behaviours) from twice to once weekly and for BED the duration of symptoms was aligned with bulimia nervosa to be 3-months rather than 6-months [4]. EDNOS has also been revised into two new categories: Other Specified Eating or Feeding Disorder (OSFED) and Unspecified Feeding or Eating Disorder (UFED). OSFED has two groups characterized by recurrent binge eating, namely, sub-threshold bulimia nervosa and sub-threshold BED where binge eating frequency and/or the duration of compensatory behaviours are less than weekly for three months. A further overeating subtype of OSFED, night eating syndrome, does not specify that the excessive food consumption entails binge eating episodes.
The DSM-5 revisions have empirical support and are likely to also be introduced in upcoming revisions of the alternate international diagnostic scheme, namely, the International Classification of Diseases [5]. The ICD revisions may however go further in removing the requirement that binge eating episodes entail consumption of an unusually large amount of food, such that people who experience a loss of control over eating but who binge on normal sized food portions – i.e., people who have subjective binge eating episodes – may be eligible for the diagnoses of bulimia nervosa and BED. This is supported by evidence that that the size of the binge is of less clinical utility, diagnostic validity and concern to people who binge than is the experience of being out of control when eating (e.g. Latner and colleagues [6] and Mond [7]).
Criteria for new disorders in DSM-5 depart from those for anorexia nervosa and bulimia nervosa in not requiring the overvaluation of weight/shape or other body image disturbance. However, overvaluation of weight/shape has been argued to have clinical utility as a diagnostic specifier, or perhaps, diagnostic criterion, of BED [8,9]. New disorders such as BED also appear to have different demographic correlates to anorexia nervosa and possibly bulimia nervosa, occurring in older people with a more even sex distribution [10]. There is also potential for people to meet criteria for more than one disorder depending on interpretation of the term “recurrent” in regards to purging episodes. For example, a person who has weekly objective binge eating episodes, less than weekly purging episodes, and overvaluation of shape or weight, may be diagnosed as binge eating disorder (if the less-than-weekly purging is deemed “not-recurrent”) or bulimia nervosa of sub-threshold frequency and/or duration, i.e. OSFED.
There have been a small number of epidemiologic studies of DSM-5 anorexia nervosa, bulimia nervosa, BED, and other disorders involving recurrent binge eating. The community-based 2005 South Australian Health Omnibus Survey (SAHOS) of people aged 15 or more years [11] found a 3-month prevalence of around 1% for bulimia nervosa (84% females), 2% for BED (67% females), 2% for other EDNOS cases (69% females) and 0.3% anorexia nervosa (80% female) using the DSM-5 criteria of weekly frequency of binge eating and extreme weight control behaviours and broader criteria for anorexia nervosa (DSM-5 criteria A and C). These findings were in accord, generally, with international studies which have reported general population point or 12-month prevalence figures for DSM-IV bulimia nervosa of around 2% in women and 0.5% in men and for BED of around 3.5% in women and 2.0% in men [12-15]. Use of different diagnostic schemes, population samples, and assessment instruments likely account for variations in prevalence [16].
Estimates of the lifetime prevalence of DSM-5 eating disorders have since been derived in population-based cohort samples of young female twins by Wade and colleagues [17]. These found a lifetime prevalence of 1-2% for bulimia nervosa and an additional 2% of women met criteria for BED. In a community cohort of 699 adolescent female twins 5.4% of participants had DSM-anorexia nervosa, bulimia nervosa, or BED, 5% OSFED and 4.7% UFED [18,19]. Allen and colleagues [20] reported one-month prevalence of DSM-5 eating disorders in 1383 children of a cohort of 2804 Australian mothers. At age 20, the point prevalence of DSM-5 eating disorders was 15.2% in females (most bulimia nervosa or BED) and 2.9% in males (mostly OSFED). A community-based study of 1584 adolescents in Holland [21] found that 5.7% of the female (95% CI 4.2–7.5) and 1.2% of the male adolescents (95% CI 0.6–2.3) met DSM-5 criteria for an eating disorder in their lifetime, BED being the most common diagnosis followed by anorexia nervosa. Much higher one-month prevalence of OSFED/UFED (43%) and BED (9.9%) were reported in a sample of college age students in the US with rates for anorexia nervosa of 0.1% and bulimia nervosa 1.2% [22]. Large international variation in prevalence estimates support the need for further, population-based research.
In addition to informing community prevalence, epidemiologic surveys can inform the socio-demographic distribution of eating disorders free from the selection bias inherent in clinic samples, for example, access and availability of care [10]. Sex, age and socio-economic status are particular demographic correlates whose rates have been thought to vary across eating disorder diagnostic groups [10] with aetiologic and health care provision import. For example the sex bias towards women has been thought to be relevant to greater social pressures on women to be thin, exemplified in the book “Fat is a feminist issue” [23]. Others have relevance to access to care. For example, limited financial capacity to pay for health care and in men embarrassment with having a perceived “female” problem are important barriers to seeking help [24,25] and the misperceptions that eating disorders are uncommon in lower socio economic groups or men may thereby contribute to deficits in health care provision to these groups.
The goal of the current study was to determine the 3-month prevalence of DSM-5 disorders in a representative sample of Australian older adolescents and adults. Secondary aims were to compare the prevalence of bulimia nervosa and BED according to DSM-IV and DSM-5 criteria, and of BED with and without overvaluation as a diagnostic criterion, and to delineate the demographic correlates of eating disorder diagnoses, specifically, age, gender, household income and education level distributions.