Assessing caregiving experience in COPD: content validity of the Zarit Burden Interview in Canadian and Portuguese caregivers

Purpose Informal caregivers play an important role in chronic disease management but their experience is often neglected. The objective of this study was to explore the content validity of the Zarit Burden Interview (ZBI) in caregivers of individuals with COPD in Canada and Portugal. Materials and methods Cognitive debriefing interviews were conducted with informal caregivers of individuals with moderate to very severe COPD. Participants completed the ZBI and verbalised their thinking process to assess the adequacy of the questionnaire's content and instructions. Content validity was assessed using deductive content analysis of interviews and descriptive statistics of questionnaire responses. Results Nine caregivers from Canada (age = 67 +/- 8 years) and 13 from Portugal (age = 69 +/- 7 years) participated. For Canadian caregivers, 3/22 items were not understood, and 8/22 items were not relevant to at least 1/3 of them. For Portuguese caregivers, 1/22 items were not understood, and 20/22 items were not relevant to at least 1/3 of them. The distribution of response choices was approximately symmetrical for 17/22 items in the Canadian sample. The response option "no/never" was selected by at least 75% of Portuguese participants for 18/22 items. Conclusions The instrument was well understood by caregivers of people with COPD, but its relevance is uncertain.