OBJECTIVES: Physical functioning (PF) and symptom severity are important factors in the health-related quality of life of people living with non-small cell lung cancer (NSCLC). The objective of this study was to evaluate the validity evidence and meaningful change thresholds of two patient-reported outcome (PRO) measures in NSCLC: the Patient-Reported Outcome Measurement Information System (PROMIS) PF short form (SF) 8c as a measure of PF and the NSCLC Symptom Assessment Questionnaire (NSCLC-SAQ) as a measure of NSCLC symptom severity.

METHODS: The study included data from two Phase 3 clinical trials for patients with EGFR-mutated locally advanced or metastatic NSCLC. Analyses of the PROMIS PF included data from 300 participants in the PAPILLON trial, and analyses of the NSCLC-SAQ included 615 participants in the MARIPOSA 2 trial. Prespecified expected relationships between the target PROs and relevant study variables were used to evaluate convergent, discriminant, and known groups validity evidence, as well as each scores’ ability to detect change. Meaningful change thresholds were estimated using distribution-based and anchor-based analyses, including examination of empirical cumulative distribution and probability functions.

RESULTS: Both measures exhibited adequate internal consistency for clinical trial use. For both the PROMIS PF-SF 8c and NSCLC-SAQ, all examined correlations with reference variables and score differences between clinically meaningful groups conformed to expectations. Estimated thresholds for meaningful worsening were a decrease of 6 to 7 points on PROMIS PF and an increase of 2 to 3 points on NSCLC-SAQ.

CONCLUSIONS: This study is the first to examine longitudinal measurement properties of PROMIS PF-SF 8c and the first to establish thresholds for meaningful worsening on the PROMIS PF and NSCLC-SAQ measures. Results from this study support the validity of these instruments in NSCLC and aid the interpretation of clinically meaningful change in scores over time.