Exploring face validity of patient-reported outcomes assessing subjective norms, self-regulation, and illness perceptions in lumbar spinal stenosis: A think aloud study.

Outcome measures are essential in healthcare. This study aimed to use Think Aloud methodology to explore the face validity of three patient-reported outcome measures (PROMs)-the Subjective Norms, Self-Regulation, and Expected Illness Perception questionnaires-among individuals undergoing surgery for lumbar spinal stenosis (LSS). Twelve participants aged 59-88 verbalised their thoughts while completing the questionnaires. Content analysis revealed 96 issues across the 3 PROMs. The Expected Illness Perception and Subjective Norms questionnaires yielded the highest number of problems, particularly around phrasing and inconsistent response scales. While the Self-Regulation questionnaire was generally well understood, some items still prompted confusion. Findings highlight the importance of clear item phrasing, scale consistency, and contextual framing to reduce cognitive burden and enhance usability. Recommendations for item revision are provided to improve face validity and interpretability. Further qualitative and quantitative evaluation in a more diverse participant population is warranted before clinical or research use.