Definitions
1. For the purpose of this study, we considered three scenarios in the timeline treatment of a total of 30 sessions (1 individual + 29 group sessions). The aim was not to investigate "percentage of sessions attended" but rather the timing of attrition (early/middle/late). So, we present 3 time points in a way that there is a continuum:
a. 33% of presence, corresponding to 10 sessions with no other requirement.
b. 60% of presence, corresponding to 18 sessions with no other requirement.
c. 75% of presence, i.e., (i) completed the treatment until the final session and missed less than 4 sessions in a sequence, and/or (ii) completed at least 22 out of 30 sessions.
The 33% treatment completion is clinically relevant as it is of interest who will engage in treatment. Early dropouts are of concern as they benefit little from the intervention. The 75% treatment completion is also clinically relevant as reflects those who will complete most of treatment, and thus may benefit most from the intervention. So, both 33% and 75% treatment completions have clinical utilities. However, we also chose 60% treatment completion on the ground that there is no consensus on what is treatment completion or number of sessions for treatment to be completed [1, 8]. However late attrition is usually 75% or more of therapy sessions and has been applied in previous studies of the authors [8].
2. Frequency of binge eating episodes was considered when the participant reported at least one episode per week during the last 3 months.
3. Purging was defined as any current use of self-induced vomiting, laxatives, and/or diuretics as a method of weight and/or shape control within the past 3 months. It could be compensatory or non-compensatory.
Participants
We aimed to include 100 participants in the protocol, but had to stop at 98 people, when two participants were randomised but failed to engage in treatment due to time to finish the trial allowed by the research funding agency. Thus, this secondary analysis study comprised a sample of 98 participants, adults, both genders, with BMI ≥ 27 and < 40 kg/m² (either overweight or obese), recruited from clinical and community sources, with threshold or subthreshold BN or BED diagnoses, according to the Diagnostic and Statistical Manual of Mental Disorders, fifth edition (DSM-5) [9]. Sixty-six (67.3%) participants met the DSM-5 diagnostic criteria for BED and 13 (13.3%) for BN. Of the remaining 19 participants, 5 (5.1%) had other specified feeding or eating disorder (OSFED) BED-type, 7 (7.1%) had OSFED BN type and 7 (7.1%) unspecified feeding or eating disorder (UFED). Of those receiving UFED diagnosis, all reported regular recurrent binge eating, but five did not fulfil Criterion B or C for BED, one with recurrent binge eating and self-induced vomiting episodes did not meet Criterion D for BN, and one met all criteria for BN, but only reported subjective binge eating.
The group with threshold or subthreshold BN or BED diagnoses is not a very heterogeneous group as there are some overlaps between the two conditions.We were interested in studying effects of HAPIFED on eating disorders symptoms and weight, so we expected that cases with related features would benefit from treatment. Additionally, the observation that it is common to include subthreshold cases in RCTs has led proposals for revisions of classificatory systems to widen the diagnosis of the main categories [10]. The condition BN includes recurrent binge-eating episodes or the consumption of abnormally large amounts of food in a short period of time which is followed by self-induced vomiting, strict dieting, over-exercising and/or the misuse of laxatives, enemas or diuretics. On the contrary, if one consistently eats large amounts of food, and those eating episodes cause shame, regret, guilt, or sadness, one may have BED.
The exclusion criteria were: use of weight loss medication; clinical conditions that could interfere with appetite regulation; history of bariatric surgery; current diagnosis of psychosis or bipolar disorder; high level of suicide risk; and, current participation in psychotherapy for eating disorders. This RCT was conducted by specialists at a university centre for treatment of eating disorders (PROATA) in the Universidade Federal de São Paulo, Brazil. Participants were recruited from July 2015 to November 2017, via waiting list, advertisements in the internet, printed and oral media.
All participants were evaluated in three stages (see trial protocol for details) [4]. The third stage comprised the assessment with a semi-structured interview that confirmed the eating disorder diagnosis and detailed eating disorders symptoms and behaviour. In total, ten groups were organized, with 5 groups receiving the experimental intervention (HAPIFED) and the other 5 groups receiving the control intervention (CBT-E). An investigator (PH) external to the site conducted the allocation through a website www.sealedenvelope.com. The randomisation process was concealed from the statistician involved in the analysis, and only the therapists of the Brazilian research team knew it until the finalization of the 12-month follow-up after the end of the active treatment. See the flow chart (Figure 1).
Four female therapists were guided in agreement with CBT-E and HAPIFED manuals. They were trained by experienced therapists (PH and Jessica Swinbourne) receiving monthly telephone supervision during the 2 pilot groups, and monthly telephone supervision during the trial by PH who visited Brazil 6 times in 3 years for face-to-face supervisions with the Brazilian therapists and other members of the HAPIFED project. Each pair of therapists conducted both CBT and HAPIFED groups to administer the non-specific therapists’ effect.
For both interventions were offered an initial individual session and more 29-group sessions, being twice weekly for the first four weeks and weekly after that until the end of active treatment comprising a total of 6 months. HAPIFED is a multidisciplinary program including four sessions with dietician and/or occupational therapist accompanied by the psychological therapists. Differently from CBT-E, HAPIFED emphasizes a nutritional counselling gave by the nutritionist, the behavioural monitoring including appetite cues directed to the hunger and satiety perception, the behavioural activation, e.g. stimulate the remission of body avoidance, healthy exercise encouragement, and emotion regulation skills mainly focusing in mood intolerance. Despite CBT-E originally be offered in 20 sessions, in this protocol the number of sessions were extended in number of sessions and duration to equate to HAPIFED. Besides that, both interventions received four group follow-up sessions during the first 6 months’ follow-up after the end of the active treatment, and a final assessment was conducted in 12-month follow-up.
Measures
For the purpose of this study, the following instruments were used:
- For the evaluation of frequency of binge eating episodes, purging behaviour and eating disorder symptom severity: the semi-structured Eating Disorder Examination Edition 17.0D (EDE) [11] interview was used. The EDE generates eating disorder diagnoses and assesses the symptom severity using four subscales, which are averaged for a global score. The version 16.0 was translated to Brazilian/Portuguese with a satisfactory reliability (80% inter-interviewer agreement and 0.69 Kappa were evaluated with considering the diagnosis using the EDE interview) and concurrent validity (77.3% agreement and 0.68 kappa). For a consistency with the most recent edition - EDE 17.0D – small modifications were made in the previous Portuguese version, in order to derive DSM-5 diagnoses.
- After a first screening by telephone, the eligible participants were invited for a first presencial interview when the informed written consent was signed, the inclusion and exclusion criteria were rechecked and a medical history and physical examination were conducted by a clinical physician. Weight and height were measured using a calibrated, electronic digital scale and a stadiometer, from which BMI (kg/m²) was calculated.
- For the evaluation of mental health-related quality of life: the 12-Item Short Form Survey (SF-12) [12] was applied. The SF-12 is a self-report instrument that measures physical and mental health-related quality of life.
- For the measurement of eating disorder illness duration: the participants fulfilled a self-report questionnaire where they were asked about the illness duration. In the first interview, a self-reported questionnaire was completed by the participants with sociodemographic information (age, sex, occupation, marital status, etc) and the illness duration where they needed to complete a space with years and months, e.g., Illness duration: ..... years and ..... months.
Participant Flow
As we aimed to study early, middle and late treatment attrition three time points, 33%, 60% and 75%, were analysed. Figure 1 is a flowchart showing how the eligible number (n=98) of participants was arrived at and the number of participants completing at least 10 or 33% sessions, at least 18 or 60% sessions and at least 22 or 75% sessions. This figure shows that the number of participants for these treatment attrition three time points were 71, 51 and 45 respectively.
Statistical analyses
Data were cleaned including correcting for coding errors. Descriptive statistics such as mean for a continuous covariate and its standard error, as well as proportion for a categorical covariate and its standard deviation were estimated for completers and non-completers of sessions. It was more clinically useful to know if sufficient sessions were attended that a therapist would be satisfied the person had ‘completed’ therapy. Fewer sessions than this the therapy may have been less effective because it was incomplete. So the dependent variable identified a decision issue and hence was clearly dichotomous and so treating it as continuous would not be informative to clinicians. Logistic regression analysis was thus performed to determine the significant predictors of treatment completion. The maximum likelihood estimation was not used to fit the logistic models for predicting the odds of completing at least 18 and 22 sessions as they did not satisfy the widely used criterion of having at least 10 events per predictor for using maximum likelihood in logistic regression. For these models the penalised likelihood with Firth’s correction [13] was used as it should perform much better in estimating unbiased regression coefficients. The missing data were estimated in the analysis by multiple imputation using multivariate normal imputation. All analyses were performed using SAS version 9.4 [14].