Holland Sleep Disorders Questionnaire: a new sleep disorders questionnaire based on the International Classification of Sleep Disorders-2.

The primary objectives of this study were to construct a self-assessment questionnaire for sleep disorders based on the International Classification of Sleep Disorders-2, and to evaluate the questionnaire's psychometric properties with respect to its total score and the individual scores for each of the six sleep disorders. In total, 1269 patients, clinically diagnosed with a sleep disorder, and 412 subjects without sleep complaints were enrolled into this study. Principal components analysis confirmed that the Holland Sleep Disorders Questionnaire differentially represented the six symptom clusters associated with International Classification of Sleep Disorders-2 classifications. The Holland Sleep Disorders Questionnaire's total score distinguished patients with a clinically diagnosed sleep disorder from individuals without sleep complaints, with area under the receiver operating curve P(A) of 0.95. The internal reliability coefficient alpha was 0.90 and, applying the Youden criterion as cutoff score, the overall accuracy was 88% (κ: 0.75). Subsequently, the six diagnostic groups of sleep-disordered patients could be differentiated reliably, with P(A) values ranging between 0.69 and 0.95, alpha coefficients ranging between 0.73 and 0.81 and an overall percentage of 85% correctly classified patients (κ = 0.80), indicating a substantial to excellent agreement between the primary diagnoses and the Holland Sleep Disorders Questionnaire classifications.