Changes in Outcomes of Treatment for Adolescent Anorexia Nervosa After Implementation of Family Based Treatment in a Norwegian Child and Adolescent Mental Health Service: A Retrospective Cohort Study With Prospective Follow-up
Conditions: Anorexia Nervosa, Atypical Anorexia Nervosa
Sponsor: University Hospital, Akershus

 
 
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STUDY PROTOCOL 
Full project title: Changes in outcomes of treatment for adolescent anorexia nervosa after 
implementation of Family Based Treatment in a Norwegian child and adolescent mental 
health service: A retrospective cohort study with prospective follow-up  
Short project title and acronym: Akershus university hospital retrospective cohort study of 
family based treatment / ARCS-FBT 
Short Norwegian title for public communication: Familiebehandling av anoreksi – effekt og 
erfaringer med innføring av FBT-modellen 
SUMMARY  
A two-group retrospective exploratory cohort study with longitudinal follow-up comparing 
adolescents with anorexia nervosa treated with generic family therapy to those treated with the 
manualised Family Based Treatment (FBT). The primary aim is to investigate whether adoption of FBT 
has led to faster normalisation of weight and lower rates of eating disorder in early adulthood. 
Secondary aims are to investigate whether implementation of FBT has changed the time to discharge, 
heterogeneity of patient weight change across treatment, rates of adverse events, rates of 
readmission, patient experiences of the treatment, long term functional outcomes and mortality. Data 
are extracted from patient health records, reported by participants and extracted from public 
registries. 
STUDY MANAGEMENT AND RESEARCH GROUP 
This study will be conducted by the Department of child and adolescent mental health services at 
Akershus university hospital. Director of research and innovation, professor Helge Røsjø, is 
responsible for research at Akershus university hospital. Head of Department Morten Grøvli has the 
administrative responsibility for the project on behalf of the hospital. 
Project manager and principal investigator: 
Erling W. Rognli, PhD 
Clinical psychologist, Department of child and adolescent mental health services 
Project group: 
Hanne C. Kaspersen, MD  
Consultant, Department of child and adolescent mental health services 
Marianne Aalberg, PhD 
Senior researcher, Department of research and development in mental health 
Victoria Frivold, MPhil 
Research coordinator, Department of child and adolescent mental health services 
BACKGROUND 
Adolescent anorexia nervosa is a severe eating disorder related to long-lasting morbidity and 
premature mortality (1, 2), and recent reports from hospitals suggests the prevalence in Norway may 
be increasing (3). The manualised family therapy “Family Based Treatment” (FBT) is currently the 
treatment approach for adolescent anorexia nervosa with the largest evidence base (4). FBT is 
recommended as a first line treatment in multiple service contexts (5, 6). 
While there has been conducted several randomised controlled trials of FBT in academic settings (7), 
there are few large studies examining outcomes when FBT is implemented in clinical practice. A 

 
 
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systematic review published in 2015 found five such dissemination studies. Of these, three were 
conducted in academic clinical settings with the number of patients ranging from 11 to 20, and two 
were retrospective studies reporting changes in service use patterns after implementation of FBT in a 
regular mental health service (8). Two later studies have compared the outcomes achieved in clinical 
trials of FBT to those of FBT provided in regular clinical care, finding these to be comparable (9, 10), 
but these have both been conducted in highly specialised clinical contexts. More studies with higher 
power are needed to confirm the effectiveness of FBT when disseminated to regular healthcare 
contexts. 
At the Child and Adolescent Mental Health Service (CAMHS) unit Nedre Romerike BUP, adolescent 
anorexia nervosa has consistently been treated with family therapy for about 20 years. In 2018 the 
unit implemented FBT, making several changes to the form of family therapy provided. As part of 
treatment monitoring, patients are weighed regularly, and weight data are recorded in patient health 
records.  
Restrictive eating and corresponding weight loss are core features of anorexia nervosa, besides 
distorted views of the body and rigid preoccupation with losing weight and avoiding weight gain. 
Normalisation of eating behaviour and weight status is hence the primary treatment goal, making the 
patient health records in this case contain relevant outcome data. 
The long-term course of anorexia nervosa is heterogeneous, and in some patients the disorder shows 
a protracted course, with long term morbidity and functional impairment, as well as increased 
mortality (11). There are few longitudinal studies of treatment outcomes with long follow-up periods 
(12). As Norway has a general system of personal identification numbers, following up patients across 
multiple public registries is a viable way to assess long term outcomes without the patients needing to 
participate in reporting. 
AIMS 
The primary aim is to assess the short and long-term effectiveness of FBT compared with non-
manualised family therapy. This is operationalised as testing whether the adoption of FBT has led to 
patients achieving normalisation of weight faster than with the previously delivered family therapy, 
and whether it will lead to less treatment provided for eating disorders in adulthood. Secondary aims 
are to assess whether adoption of FBT have resulted in reduced time to discharge, changed the 
heterogeneity of weight gain across patients, whether there have been changes in the rates of adverse 
events and readmissions, and to assess whether the implementation of FBT has led to changes in long-
term functional status and rate of mortality. 
DESIGN AND METHODS 
Participants and recruitment 
This is a two-group retrospective exploratory cohort study with prospective longitudinal follow-up in 
public registries. Eligible participants are all patients initiating treatment during the years 2015-2020 
with the eating disorder team at Nedre Romerike BUP with a primary ICD-10 diagnosis of F50.0 
Anorexia nervosa or F50.1 Atypical anorexia nervosa. Patients will be excluded if they were treated 
during the years 2018-2020 and FBT was never initiated. It is estimated that the final sample size will 
be approximately 200.  
Eligible participants will be identified through review of patient health records. Participants will be 
contacted by letter with information about the study, including a link to an online video explaining 
more about the study. Study personnel will make a follow-up telephone call approximately a week 
later to allow the eligible participant to ask any questions they may have before deciding on 
participation in the study. Participants who are interested in participating will be directed to a website 

 
 
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where they can sign an electronic consent form and complete a short survey about their experience of 
treatment. The consent form and treatment experience survey will be implemented in “Tjenester for 
Sensitive Data”, which has appropriate security and allows for verified electronic signatures. 
Participants will be contacted after they have reached age 16, and thus are able to give informed 
consent. They will be encouraged to discuss participation with their parents or other legal guardians. 
Endpoints and data collection 
Primary endpoint for the retrospective study is weight restoration, defined by patients having a weight 
measurement placing them at or above 95% of expected body weight (50. percentile) for age given 
Norwegian population norms, following established definitions of weight restoration (10). 
Secondary endpoints are discharge from treatment and readmission to treatment (the latter is 
assumed to be right-censored). 
Adverse events will be defined as debut of suicidal ideation, attempted suicide, debut of self-harming 
behaviour, severe self-harm where medical attention is indicated, hospitalisation for low weight or 
medical complications from low weight, admission to inpatient treatment for anorexia nervosa, 
involuntary gastric tube feeding, parental separation, and initiation of contact with child protective 
services. 
Participant experiences and satisfaction with services will be assessed using the Generic Short Patient 
Experiences Questionnaire (GS-PEQ) (13). 
The primary endpoint for the prospective study is continued morbidity, defined as being currently in 
treatment in specialist health care for any eating disorder. Secondary endpoints are mortality, level of 
education and employment status. 
Data for the retrospective part of the study will be extracted from electronic patient health records. 
Weight data will be extracted directly from the electronic patient health record system (DIPS). One 
researcher will further go manually through all records of included patients and extract dates of 
treatment start, adverse events, discharge and any readmission, as well as checking the record for any 
weight measurements recorded but not entered into the weight database. As covariates we will also 
extract age, sex, gender, family structure, extent of care benefits received during treatment 
(pleiepenger), and comorbid disorders (ICD-10 diagnoses). Another researcher will independently 
extract data from a random 10% subsample for control and reliability assessment of coding. 
Each participant will be assigned a random case identity number, which will be used for identification 
in all dataset files when data is analysed. Participant national identity numbers will be stored along 
with the corresponding case identity number in a separate file, the identity key file. Access to the 
identity key file will be restricted to the project manager and researchers performing data extraction. 
It will also be delivered to the agencies maintaining the relevant public registries. 
When extracted, data will be entered directly into a REDCap database maintained by Akershus 
university hospital. Access will be restricted to researchers in the project group. Data will be stored 
and analysed de-identified. 
Data for the prospective part of the study will be acquired from the following public registries: 
Norwegian Patient Registry, Norwegian Cause of Death Registry, and the databases “Attachment to 
employment, education and welfare benefits” and “Educational attainment of the population” 
collated by Statistics Norway. Data will be acquired from these databases in three waves; five, ten and 
twenty years after the last participant initiated treatment. All registry data will be acquired, stored and 
analysed de-identified. 

 
 
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Analysis plan 
Statistical analysis will be conducted in a Bayesian framework using the Stan platform through the R 
(14) package brms (15). 
We will evaluate whether adoption of FBT has led to faster weight normalisation by fitting a parametric 
survival model to the number of days until weight restoration is achieved. We will also fit models with 
gender, age, baseline weight, comorbid disorders and family structure as covariates, and further 
investigate whether any of these act as moderators of FBT compared with previous treatment. Similar 
parametric survival models will also be used for modelling differences in time to discharge and 
readmission. Differences in the rate of adverse events will be modelled using Poisson regression. 
We will also evaluate differences between the cohorts in treatment course by fitting multilevel spline 
models to weight data with knots for every 4 weeks in treatment. Weight measurements will be nested 
within patients, and patients nested within cohorts. Spline models will allow for modelling non-linear 
weight change over the course of treatment, and the multilevel structure at the patient level will allow 
us to evaluate changes in heterogeneity of treatment response pre and post adoption of FBT, as well 
as visualise trends and heterogeneity of weight change across the course of treatment. 
Analysis of prospective data will use parametric survival models or logistic or ordinal regression 
models, depending on the level of time specificity available in the data. 
We have conducted simulations to investigate statistical power, assessing the type S (sign) and type M 
(magnitude) error rates, given inference based on the posterior median. We made the assumption of 
achieving at least a sample size of 150 patients and that implementation of FBT has led to a 10% 
increase in the probability of an event (i. e. weight restoration or discharge). With 1000 simulations, 
we estimated a type S error of 0.00 and an M error of 0.89, suggesting a very low risk of estimating the 
sign of the effect incorrectly and a small risk of underestimating the effect size. We conclude that the 
study will be adequately powered to achieve its primary aim. 
The analysis will employ weakly informative prior distributions, using previous studies and other 
external knowledge (for instance about the biological limits of weight gain per day) to construct priors 
that rule out impossible areas of the parameter space (17). 
ETHICAL CONSIDERATIONS 
This study does not involve any direct experimental manipulation, and as long as the process of 
extracting and analysing data from patient health records and public registries is conducted with due 
care, there is no risk of harm to the participants. FBT has been widely implemented in Norwegian 
health care based on findings from experimental studies in treatment settings quite different from 
regular public healthcare services. Research on the short and long-term effectiveness of FBT in a 
Norwegian context hence has considerable value to society and future patients receiving treatment 
for anorexia nervosa. 
STUDY TIMELINE AND PLANS FOR DISSEMINATION 
The study was approved with qualifications by the Regional Ethics Committee in 2021 with a 
requirement to adjust the protocol to seek informed consent from all participants or their legal 
guardians. Final approval was granted in July 2022. The process of identifying and contacting eligible 
participants will start as soon as approval is received. 
Data extraction for the retrospective part of the study will start for each participant as soon as 
informed consent is obtained. It is expected to be finished at the latest in the fourth quarter of 2023, 
with reliability checking completed within 2023. Preparation of computer code for analysis will be done 
concurrently, and analysis will commence when data extraction is completed. Preparation of reports 

 
 
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for publication will be done during 2023 and early 2024. Findings will be submitted to international 
scientific journals specialising in eating disorders. Abbreviated reports of findings will also be prepared 
and submitted to the journals of relevant Norwegian professional associations. 
For the prospective part of the study data will be extracted in four waves, when the participant last 
initiating treatment has reached the planned time for follow-up and registries are updated. An 
individual follow-up date will be calculated for each participant, to adjust for differences in when 
participants initiated treatment, and the closest relevant registry entry to that date will be extracted. 
The project group will consult with the agencies maintaining the registries to plan data extraction in 
detail. Findings from the prospective part of the study will be reported in international scientific 
journals as they become available. 
DATA RETENTION 
Documentation for the clinical study will be retained for five years after final study report/publication. 
FUNDING AND CONFLICTS OF INTEREST 
The study is fully funded by the Department of child and adolescent mental health services at Akershus 
university hospital, through time allocated for research for the researchers who are employed at the 
department. Dr. Kaspersen works as a clinician treating eating disorders at the Nedre Romerike CAMHS 
unit, but has worked there before and after implementation of FBT, and does as such not have a 
conflict of interest relating to the results of this study. Dr. Rognli, Dr. Aalberg and Ms. Frivold have no 
conflicts of interest. 
DECLARATIONS AND POLICIES 
Amendments to the research protocol 
The research protocol may require to be amended during the conduct of a clinical study. Any 
amendment to the research protocol will be agreed upon between the representative for the research 
responsible institution and the principal investigator. The amendments will be approved by the ethics 
committee. 
Deviations from the research protocol 
The study will be performed in accordance with this research protocol. Any protocol deviations will be 
reviewed by the representative for the research responsible institution. All deviations will be reported 
to the appropriate regulatory bodies as required. 
Statements of compliance 
The study will be performed in accordance with the ethical requirements defined in the Declaration of 
Helsinki. The study will not commence until all written approvals have been obtained. 
Publication policy 
Upon study completion the results of this study will either be submitted for publication and/or posted 
in a publicly accessible database of clinical study results. The results of this study will also be submitted 
to the Ethics Committee according to national regulations. All personnel who have contributed 
significantly with the planning and performance of the study (Vancouver convention 1988) may be 
included in the list of authors. 
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