The Reliability of a New Sleep Screening Questionnaire for Large Population-Based Studies: The Third Nord-Trøndelag Health Study

The aim of the present study was to evaluate the reliability of a new sleep questionnaire (sHUNT-Q) used in the Nord Trondelag Health Study 3 (HUNT 3) performed between 2006 and 2008. Six of nine items were modified from a Norwegian version of the Karolinska Sleep questionnaire (KSQ). Overall, 50,839 (54%) out of 94,194 invited participated in HUNT 3. In a randomly selected group of participants, 297 (53%) out of 563 invited persons attended an interview by neurologists. The reliability of the sleep related questions was evaluated with Cohens kappa by blindly comparing the an- swers in the questionnaire with those from the semi-structured interview. Summary measure scores were calculated by summing the responses of the six modified KSQ questions, the three insomnia-related questions, and the two questions re- lated to respiratory disturbance during sleep. Agreement was calculated for dichotomized sum-score indexes based on 75% and 50% percentile cut-offs. Kappa values for the individual questions ranged from 0.35 to 0.52 in 3 x 3 tables while kappa for summary indexes in 2x2 tables ranged from 0.47 to 0.62. The best agreement between the interview and the questionnaire was found for respiratory disturbance defined as a summary measure score � 50 percentile (kappa value 0.62, 95% CI 0.51-0.74). Reliability did not depend on the time between the HUNT questionnaire and the interview. The KSQ-based summary measure scores from the new sHUNT-Q sleep screening questionnaire may become a useful tool in epidemiological studies for identifying individuals with a persistent sleep disturbance.