Development of the Functional Assessment of Cancer Therapy-Carcinoid Syndrome Symptom Index

Objective: To develop a symptom-focused index to evaluate representative symptoms, treatment side effects, and emotional and functional well-being of patients with carcinoid syndrome (CS). Methods: The development of the Functional Assessment of Cancer Therapy-Carcinoid Syndrome Symptom Index (FACT-CSI) followed US Food and Drug Administration guidelines for the development of patient-reported outcome (PRO) measures and involved the following: (a) literature review; (b) interviews with 14 CS patients; (c) interviews with 9 clinicians; and (d) instrument development involving input from a range of PRO measure development and CS experts. The resulting draft instrument underwent cognitive interviews with 7 CS patients. Results: Forty-six CS sources were reviewed. Analysis of patient interviews produced 23 patient-reported symptoms. The most frequently endorsed physical symptoms were flushing, diarrhea, abdominal pain, fatigue, and food sensitivity/triggers. Seven priority CS emotional and functional themes were also identified by patients. Expert interviews revealed 12 unique priority symptoms - the most common being diarrhea, flushing, wheezing, edema, abdominal pain/cramping, fatigue, and 8 emotional and functional concerns. Through an iterative process of team and clinical collaborator meetings, data review, item reduction and measure revision, 24 items were selected for the draft symptom index representing symptoms, emotional concerns, global assessment of treatment side effects, and functional well-being. Cognitive interview results demonstrated strong content validity, including positive endorsement of item clarity (>86% across items), symptom relevance (>70% for most items), and overall measure content (86%). Conclusions: The FACT-CSI is a content-relevant, symptom-focused index reflecting the highest priority and clinically relevant symptoms and concerns of people with CS.