OBJECTIVES : Patients often use a variety of words to describe similar disease experiences, leading to challenges during analysis and concept selection for patient-reported outcome (PRO) measures. This study aimed to determine if conceptually similar symptoms and impacts are defined as the same or different among patients with different diseases.

METHODS : RESULTS : A total of 419 subjects were enrolled, with n=104 for all disease groups except depression (n=107). More than two-thirds of the sample identified “annoyed” and “irritated” (87.3%), “tired” and “fatigued” (86.3%), “irritated” and “aggravated” (82.2%), “frustrated” and “aggravated” (75.9%), and “sad” and “depressed” (67.7%) as conceptually the same. The only words categorized as different by more than two-thirds of the sample were “not confident” and “embarrassed” (80.8%). Subjects did not provide definitive responses (i.e., no group achieved two thirds agreement in either direction) for the remaining pairs. Results showed little variation across disease groups.

CONCLUSIONS : Words patients use to describe disease concepts do not always align with clinical and regulatory definitions. As patients use words interchangeably, concept-level analysis can help narrow the selection of items and produce more concise questionnaires. The homogeneity of results across disease groups suggests that patients’ vocabulary is not impacted by the underlying disease state (e.g., a depressed patient is as likely to report “sad” and “depressed” as conceptually the same as a non-depressed patient). For words identified as conceptually the same, factors like readability or translatability should be considered and perhaps prioritized when selecting language used in PRO measures.