Content validity of the NCCN-FACT ovarian symptom index-18 (NFOSI-18)

Abstract

Objective: This study examined the content validity of the NCCN-FACT Ovarian Symptom Index-18 (NFOSI-18), an advanced ovarian cancer symptom index comprised of symptoms perceived as most important by clinical experts and women with advanced ovarian cancer.

Methods: Eighteen women with advanced ovarian cancer completed the NFOSI-18 and participated in cognitive interviews to assess: (a) the understandability of the NFOSI-18; and (b) the things patients have in mind when responding to the item, "I am bothered by side effects of treatment;" and (c) the interpretation patients place on items relating to fatigue and lack of energy. Interviews were recorded and transcribed for qualitative analysis.

Results: All but 2 (89%) participants indicated that each item was clear and understandable and the same proportion (89%) stated they were "very confident" or "confident" about providing accurate answers to all but one item. When responding to the item, "I am bothered by side effects of treatment," fatigue, nausea, and neuropathy constituted the most frequently mentioned concerns. Among the participants who were asked, eight participants responded that "fatigue" and "lack of energy" were the same concept and nine responded they were different. Participants associated "fatigue" with tiredness and associated "lack of energy" with the inability to perform daily tasks and activities.

Conclusions: The findings support the content validity of the NFOSI-18. Item revisions, deletions or additions do not appear warranted. Future research can address the reliability and validity of the NFOSI-18 in clinical research.

Keywords: Content validity; Ovarian cancer; Patient-reported outcome; Quality of life; Symptom index.