Content validity of the National Comprehensive Cancer Network - Functional Assessment of Cancer Therapy - Breast Cancer Symptom Index (NFBSI-16) and Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function Short Form with advanced breast cancer patients

Background: The purpose of this study is to evaluate the content validity of the National Comprehensive Cancer Network - Functional Assessment of Cancer Therapy - Breast Cancer Symptom Index (NFBSI-16) and the Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function Short Form 10b among patients with hormone receptor positive (HR+)/human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer. Methods: Cognitive debriefing interviews sought to evaluate patients' ability to read, understand, and meaningfully respond to the questionnaires, as well as to evaluate the questionnaires' relevance in the target patient population. Interviews were conducted by telephone and lasted approximately 90 min. Audio recordings were transcribed, anonymized, and analyzed using qualitative data analysis software. Results: Fifteen cognitive debriefing interviews were conducted with women (mean age 66.0 years [standard deviation = 12.4]). Patients reported metastases in the bone (86.7%), liver (20.0%), lung (13.3%), skin (6.7%), and lymph node (6.7%) (not mutually exclusive). All patients for whom data were available demonstrated understanding of the instructions and the recall period of the NFBSI-16 (n = 14/14, 100.0%) and the PROMIS (n = 14/14, 100.0%). Greater than 90% of patients demonstrated understanding of each of the items in the NFBSI-16 and the PROMIS. Greater than 70% of patients demonstrated understanding of the response options of the NFBSI-16, > 90% understood response options of PROMIS Items 1-6, and ≥ 50% understood response options of PROMIS Items 7-10. Conceptual relevance was supported for most items in both questionnaires based on patients' reports of experiencing the concepts as part of their breast cancer experience. Conclusions: The results of the cognitive debriefing interviews provide evidence that the NFBSI-16 and PROMIS Physical Function Short Form 10b have content validity in the HR+/HER2- advanced breast cancer patient population. Patients may benefit from additional instructions at the point the response options reverse direction in the PROMIS.