Study design
The study will involve a trial (open randomised parallel group control trial) with patients allocated to receive either usual care or the bariatric rehabilitation service (BRS) pre and post bariatric (obesity) surgery. Follow up measures will be recorded at 3, 6 and 12 months post-surgery at routine follow-up clinics or by post. In addition, qualitative interviews will be carried out with 20 participants from both arms of the trial (BRS n = 10; usual care n = 10). This study received a favourable ethical opinion from the Kent Research Ethics Committee, National Research Ethics Service.
Development of the intervention
The content of the BRS and the follow up measures are based on previous qualitative research and pilot work exploring what bariatric patients want and why bariatric surgery either fails or succeeds from the patients' perspective [6–8]. Furthermore, pilot research has explored the impact of bariatric surgery on changes in mood, cognitions and eating behaviours. The quantitative measures and qualitative responses derived from these studies formed the basis of the intervention and the measures for the present study.
Participants and recruitment
St Richard's Hospital in Chichester, West Sussex, UK, offers a NHS based bariatric service for obese patients with a BMI over 40 (or 35 with serious co morbidities). This is the largest centre in the UK, with approximately 500 patients per year receiving a bariatric operation at this clinic (70% being a primary bypass and 20% bands (the remaining 10% are revisions)). Patients will be recruited if they have been approved for surgery and had their date set for their operation.
Patients will be included if they consent, are aged 18 or over, have attended the bariatric clinic at Chichester, been accepted for surgery and have funding in place (i.e. the PCT has agreed to pay for their surgery). Recruitment will take place over a 12 month period. Those who cannot effectively read or speak English will be excluded as this would pose a difficulty for implementing the intervention and for data collection.
Randomisation
All patients who fulfil the inclusion criteria will be given an information sheet. They will be given several weeks to read the information and then they will be approached by the researcher, asked if they have any questions regarding the information sheet and if interested offered a written consent form. Once a patient has consented the researcher will reference the third party blinded randomization, which will be provided by the clinical trial unit at Surrey University, to indicate whether they are allocated to either the BRS or usual care.
Sample size and power calculation
Petrie et al [12] carried out an intervention (34 controls and 31 in the intervention group) with patients post MI which involved the addition of a health psychologist to usual care who focused on a number of psychological factors including beliefs, expectations and behaviour. The results from this study showed that this intervention produced a significant improvement in a certain patient outcome by follow up of about 20% with a standard error of 40%. Based on the information from this study, were the study to be repeated, 85 subjects in each arm would be needed for 90% power for the effect of the intervention on this patient outcome at a two-sided significance level of 0.05. It can be argued that this can be used as the basis for considering the expected improvement for the present study. Buchwald et al [13] reported that the mean percentage of excess weight loss among obese patients offered bariatric surgery was 62%. If the psychological intervention described here improved this weight loss by a further 20% (i.e. to 74%), by the above reasoning, at 0.05 significance 85 patients randomised to each group would give 90% power to demonstrate statistical significance of the intervention. Bands are expected to constitute 20% of all presenting patients. If 90% power is required to find the intervention statistically significant for bands and for bypass, separately, then 85 patients will need to be randomised for each of bands and bypass for each arm of the study. However we hypothesise that bands will be more responsive to the intervention than bypass and hence we will aim for 60 bands and 85 bypass patients in each of the two arms of the study, making a total of 290 patients for the study. Allowing for some attrition and refusals we propose to invite 335 patients to be recruited into the study, ensuring that 180 of these are bands and the remainder bypass. This sample size will enable us to detect a 20% improvement on usual care in the entire sample with power in excess of 90% and will also enable us to carry out some sub group analyses to explore differential effects with 90% power within those patients who receive either a gastric band or a gastric bypass.
Procedure
Patients attend the bariatric clinic for a multidisciplinary assessment day where they are told if they will be getting the surgery. If they are accepted for surgery they are given an information sheet concerning the present study. Two weeks prior to their operation patients will attend the bariatric clinic for a preoperative appointment where they will have routine tests. At this appointment patients will see the researcher who will explain the trial, obtain informed consent and randomly allocate the patient to either the usual care condition (control group) or the bariatric rehabilitation service (BRS) condition (intervention group). Patients will then complete the baseline questionnaire and either see the health psychologist or not depending on to which condition they are allocated. All patients, from both groups, will complete follow up questionnaires at 3, 6 and 12 months.
Control group
Those allocated to the usual care (control) group will receive usual management which involves preoperative tests and an information sheet post-operatively informing them about their desired diet. Patients will then return for their surgery after two weeks and after the preoperative tests and after a brief post-surgical stay they will then be discharged. The standard diet sheet they receive takes them through the stages of food progression from only consuming liquids, to soft food then back to all foods. They will return to the clinic at 3 months postoperatively to see the dietician. Patients will also attend routine follow up appointments at 3, 6 and 12 months.
Intervention group
Those allocated to the BRS (intervention group) will receive usual care as described above plus three 50 minute sessions with a health psychologist pre-operatively (2 weeks prior to surgery), post-operatively (before they are discharged from hospital) and at 3 months follow up. The design of the BRS will be based on the preparation procedures for surgery and cardiac rehabilitation services but will be tailored to the needs of bariatric patients in line with qualitative research carried out by the current author (7; 8). In addition, the BRS has been designed in line with ongoing input from users of two active support groups who have highlighted the need for increased psychological input. The health psychologist will use both didactic methods such as information giving and non didactic methods such as active listening, asking open questions and encouraging reflection. The sessions are fully structured but are flexible to work with the individual patient. In particular the service will address 5 key factors as follows: i) knowledge (ie information about dietary change); ii) beliefs (concerning the causes and solutions to obesity); iii) behaviours (with a focus on diet and physical activity); iv) coping strategies (i.e. managing emotions without using food; identifying alternative and healthy methods of coping; managing other addictions); v) adjustment (i.e. exploring ways to work with the restriction imposed by the operation).
These key elements will be tailored to each time point for each of the three sessions and the emphasis on each factor will vary according to whether the session is pre surgery, immediately post surgery or at three months follow up. The distribution of these 5 key factors across the three sessions is shown in Figure 1. The health psychologist will be given formal training in order for them to follow the same protocol for each patient in the intervention. They will be given a training manual covering background information, overview of the study protocol, along with a session plan for each of the three sessions. The training manual will be accompanied by guidelines for the focus of each session (see Figure 1) along with details of a recommended script and suggested strategies to be used in each session. In addition, the health psychologist will be asked to provide each patient with a take home message sheet to take away with them after each session which will briefly describe the issues covered in the session and any strategies agreed upon.
Primary outcome measures
Patients' weight and BMI will be obtained in the clinic to provide the primary endpoint measure of the trial. This will be collected preoperatively a couple of weeks before surgery and postoperatively at 3, 6 and 12 months follow up.
Secondary outcome measures
Baseline measures of age, sex, weight, height, educational level, and ethnicity will be taken. Patients will also be asked to complete a number of validated measures that have been used previously to assess the impact of bariatric surgery at baseline, 3, 6 and 12 months follow up to evaluate the secondary outcome measures of quality of life, mood, coping and emotional eating (i.e. ADL section of SF-36, [14], profiles of mood states, [15], COPE [16] and DEBQ, [17]).
