How well does it fit? Process evaluation of a multidisciplinary pre- and postoperative metabolic bariatric surgery...

Multidisciplinary support can help patients improve health and cope with changes after metabolic and bariatric surgery (MBS). However, there is uncertainty regarding what intervention components, delivery methods and intensity are effective. To understand how intervention effects are achieved, we performed a process evaluation of a 15-session pre- and post-MBS programme comprising medical, dietary and psychological interventions delivered via group sessions until 9 months postsurgery. The evaluation examined programme relevance, perceived fit and practicability ('appropriateness') and satisfaction with content and delivery ('acceptability'). Interviews (n = 11) and focus groups (n = 2) were performed with 21 patients in different programme phases. Programme fidelity was assessed using administrative data on attendance in 1.396 patients. Presurgery, practicing with postoperative recommendations and multiple social components, was described as useful. Although participants found several postoperative components helpful (e.g. meal planning), the perceived fit was lower due to group delivery, session spacing and varying needs. Attended programme time postsurgery was lower than presurgery. Individual needs varied in terms of support intensity and type, and by gender, age and surgery type. Participants recommended greater session spacing, as maintaining behaviours >1 year postsurgery was expected to be most challenging. Participants requested additional information on negative lived experiences, exercise and coping with various postoperative changes. Programme fit can be improved by taking patients' varying needs into account in a flexible programme, with a duration beyond the first postoperative year, and more attention to negative lived experiences, exercise and coping with changes.