Confirming content validity of The Insomnia Daytime Symptoms and Impacts Questionnaire (IDSIQ) among adults with insomnia in four European countries.

backgroundThe Insomnia Daytime Symptoms and Impacts Questionnaire (IDSIQ) v2.0 is a 14-item patient-reported outcome measure for assessing the daytime symptoms and impacts of insomnia. Content validity and measurement properties of the IDSIQ have been established among English-speakers. This study assessed content validity of translations of the IDSIQ, generated for use in clinical trials in non-English-speaking countries.

methodsThis was a cross-sectional, non-interventional, qualitative study in adults with insomnia from Denmark, Germany, Poland, and Spain. During one-on-one telephone interviews in their local language, participants answered the IDSIQ questions and described their overall impressions of the measure’s clarity, length, recall period, and comprehensiveness, as well as the overall relevance of the IDSIQ items to their experience of daytime symptoms and impacts of insomnia. They also explained their interpretation of each IDSIQ item (i.e., what they were thinking when they answered the question) and provided feedback on item clarity and the response options. Interview transcripts were translated into English and analyzed using ATLAS.ti.

resultsTwenty adults with insomnia were interviewed (five per study country, average age 46.5 years). Most participants were female (75%) and were currently receiving treatment for insomnia (70%). All participants reported that the IDSIQ instructions were clear; almost all participants reported that they understood the individual IDSIQ items (95%) and that the number of items was appropriate (95%). While 60% of participants considered “today” an appropriate recall period, 35% suggested that a longer timeframe could also be useful. Most participants reported that the IDSIQ was comprehensive in its coverage of insomnia-related experiences (80%) and that the IDSIQ items collectively were relevant to their experiences of insomnia (80%). For each item, ≥ 85% of participants felt that the wording was clear and ≥ 75% of participants would not make any changes to the response options.

conclusionsOverall, participants in European countries representing differing languages and cultures considered the IDSIQ clear, comprehensive, and relevant to their experience of daytime symptoms and impacts of insomnia. Moreover, participant feedback indicated understanding of individual items as intended. These findings support content validity of the IDSIQ after its translation into different European languages, as well as its use in future studies.