Anorexia nervosa (AN) is a biologically based serious mental disorder with high levels of mortality and disability, physical and psychological morbidity and impaired quality of life . Cognitive and emotional functioning are impaired [2–4], and motivation may be compromised due to the disorder being highly valued , making engagement in treatment difficult.
AN is one of the leading causes of disease burden in terms of years of life lost through death or disability in young women , and the cost per case of AN is at least equal to that of schizophrenia [7, 8]. Compared to other mental disorders, AN has the highest proportion of hospital admissions with a length of stay over 90 days (26.8%) and the longest median length of stay (36 days) . In one study of adolescents with AN, the annual service cost was found to be approximately 17,000 GBP , in adults with more chronic disorders this is likely to be higher. The family members are usually the main carers and report similar burden to carers of people with psychosis . A systematic review  of the costs of eating disorders identified two cost-of-illness studies, both of which underestimated the costs because of important omitted cost items. The review concludes that the costs of AN are likely to be substantial. A recent report detailed the cost of eating disorders to healthcare and wider society . It estimated a total cost for England, per year of 1.25 billion GBP. This figure includes costs to the NHS and private healthcare, the human costs and the cost of lost output. The report specifically estimated the cost to healthcare being over 80 million GBP. Most of this can be attributed to the cost of AN.
Psychotherapeutic interventions are the treatment of choice for AN, but the result of psychotherapy depends critically on the stage of the illness. Whilst response to psychological treatment (usually family-based) is excellent in adolescents with a short duration of AN , the treatment response in adults with a more chronic form of the illness is much less positive and drop-out from treatment is high . The evidence-base for psychological treatment of adults with AN is extremely limited. Several small trials have tested a range of therapies, including cognitive-behavioral therapy (CBT), interpersonal therapy (IPT), cognitive analytical therapy, and family therapy, but as yet no one treatment has been found to be the best in terms of efficacy [16, 17]. One small trial  found specialist supportive clinical management (SSCM) superior on a range of outcomes compared to CBT and IPT at end of treatment. Due to the superiority of SSCM compared with the other active treatments this intervention has been selected as the comparison treatment in this randomized controlled trial (RCT). The urgent need to develop more effective treatments for adults with AN has been highlighted [16, 17].
One of the key factors responsible for the relative lack of efficacy of treatments for adults with AN is that most of these have been adapted from those for other disorders and are neither tailored sufficiently to the characteristics and needs of people with AN nor focused on how the disorder is maintained. To remedy this problem we have developed a specific maintenance model and treatment approach for AN , the Maudsley Model of Treatment for Adults with AN (MANTRA). Our treatment model is novel in several respects: (a) it is empirically-based, drawing on and incorporating recent neuropsychological, social cognitive and personality trait research in AN, (b) it includes both intra- and interpersonal maintaining factors, and proposes strategies for addressing these and, (c) it is modularized with a clear hierarchy of procedures and tailored to the needs of the individual. Findings from pilot studies demonstrate the acceptability and efficacy of this treatment intervention among the AN patient group [19, 20].
The main aim of this study is to compare the efficacy, cost and cost-effectiveness of MANTRA in adult outpatients with AN with that of SSCM in an RCT in a new larger sample.
The subsidiary aim of the study is to explore mediators and moderators of treatment outcome.