Background: To develop and psychometrically test a condition-specific, patient-reported outcomes instrument for patients undergoing gallstone surgery.
Methods: A mixed-methods design, including six gender-mixed patient focus-groups was used. Statements were thematically analysed and compared to PROMIS and the Gastrointestinal Quality of Life Index (GIQLI). A pilot questionnaire of 63 items and the full scale GIQLI was sent to preoperative and 30 items were sent to postoperative patients. Factor analysis identified structure and redundant items. Short versions were assessed to ensure internal reliability and validity. Unidimensionality was assessed via graded response model.
Results: 273 patients completed the questionnaires (preoperatively n = 104 and postoperatively n = 169). Factor and IRT analysis identified 13 domains with 45 questions. Internal reliability 0.75 to 0.93 in the preoperative and 0.73 to 0.90 in the postoperative questionnaire. A PROM questionnaire was developed with pre- and postoperative modules (24 questions, 8 domains and 21 questions, 5 domains).
Conclusion: This study has shown the validity of a disease specific Health Related Quality-of-Life (HRQoL) instrument in a population with gallstone disease and a post-operative module for follow-up. Further testing in a longitudinal cohort is recommended in order to establish responsiveness.
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