As surgery enters the era of value-based care, it is advocated that postoperative recovery be measured using patient-reported outcomes (PROs) as they provide a mean to incorporate the patient's perspectives and experiences into research and clinical decision-making. In abdominal surgery, this is currently precluded by the lack of PRO measures specifically developed and validated in the context of postoperative recovery.

The core goal of this research project is to develop a PRO measure aimed to assess postoperative recovery from the perspective of patients undergoing abdominal surgery. This project complies with the US Food and Drug Administration (FDA) and International Society for Pharmacoeconomics and Outcomes Research (ISPOR) guidelines for PRO development and will be conducted in three phases:

Phase 1: Qualitative interviews with patients to develop a conceptual framework and generate relevant items.

Phase 2: Use of Rasch Analysis for item-reduction and scale formation.

Phase 3: Further assessment of measurement properties based on traditional psychometric methods.

OBJECTIVE:

To develop a comprehensive, conceptually relevant and psychometrically sound PRO measure to assess recovery after abdominal surgery.

OUTLINE:

• Phase 1(Conceptual framework and item generation): Semi-structured interviews focusing on patient lived experiences after abdominal surgery will be conducted to derive the "final conceptual framework of recovery after abdominal surgery". The interviews are guided by the "hypothesized conceptual framework" which is based on previous literature and expert input. This phase has a minimal targeted sample of 30 patients. To account for potential cross-cultural differences in recovery experiences, the study is enrolling patients from 4 international sites: McGill University Health Centre (Montreal, Canada), Hospital Sao Paulo (Sao Paulo, Brazil), Vita-Salute San Raffaele Hospital (Milan, Italy), and Hokkaido University Hospital (Sapporo, Japan). Interview audio recordings are transcribed, translated if required, and coded according to ICF (International Classification of Functioning, Disability and Health) domains. Codes for which saturation is reached will comprise the final conceptual framework of recovery. Items reflecting the essence of each domain will be generated and patient understanding of the items will be assessed through cognitive interviews. Items for which no problems have been identified and those successfully revised will be compiled into an item pool to be 'calibrated' in subsequent stages of PRO development.
• Phase 2 (Item selection and scoring- Rasch Analysis): In phase 2, the preliminary item pool generated in phase 1 will undergo refinement using Rasch Measurement Theory (RMT). Based on this analysis, items will be modified or eliminated to ensure that the novel PRO measure fits a linear continuum and produces meaningful scores. A target sample of 100 patients undergoing abdominal surgery will be recruited from three tertiary hospitals in Canada. The participants will complete the preliminary PRO measure at five time points: preoperatively, and on postoperative days (PODs) 1, 7, 30, and 90. Items that fail to fit the Rasch model will be revised or removed.
• Phase 3 (Validation using traditional psychometric methods): Further evaluation of the measurement properties of the novel PRO measure will be conducted using traditional psychometric methods. A total of 600 patients undergoing abdominal surgery will be recruited in five tertiary hospitals in Canada and in the United States. Participants will complete the PRO measure in different timepoints: preoperatively, and on PODs 1-7, 28, 60, and 90. Assessment of psychometric properties will focus on internal consistency, test-retest reliability, measurement error, hypothesis testing construct validity, responsiveness, and criterion validity. Interpretability will be assessed by estimating the minimal important difference (MID) using anchor-based methods.

The following applies to all phases of the project.

Inclusion Criteria:

• Age ≥18 years old
• Abdominal surgery within three days to three months before enrolment
• Fluent in the local language
• Willing and able to provide written informed consent

Exclusion Criteria:

• Documented mental impairment
• Palliative care
• Advanced musculoskeletal, neurological, pulmonary or cardiac disorders
• Organ transplantation
• Cesarean section

Patient's that have undergone abdominal surgery