Psychometric goodness of the Mini Sleep Questionnaire
The current study was conducted to evaluate the psychometric properties and analyze the convergent validity of the Italian version of the Mini Sleep Questionnaire (MSQ). In addition, it was aimed to put forward cut-off values to be used in screening protocols.
The MSQ was administered to 1830 participants (age range 18–87 years), of whom 1208 also completed the Sleep Disorder Questionnaire (age range 18–87 years). A subgroup of 187 (age range 18–71 years) participants was randomly chosen to test the test–retest reliability. A complete psychometric evaluation was performed on the MSQ. To study the validity of the tool, the Sleep Disorder Questionnaire was used as an external criterion to validate the MSQ. Using the Youden index, we calculated the cut-off values that performed best. Finally, we created receiver–operator curves to test the accuracy of each cut-off value identified.
For the MSQ, Cronbach's alpha score was 0.77 while homogeneity was 0.26. Factorial analyses confirmed the presence of two dimensions: sleep (Cronbach's alpha 0.75; homogeneity 0.37) and wake (Cronbach's alpha 0.75; homogeneity 0.44). For each dimension, a cut-off value was identified (>16 and >14, respectively). Both cut-off values obtained an area under the curve higher than 0.80.
Psychometric evaluation of the MSQ was satisfactory. The cut-off values analyzed in the present study showed good performance. On the whole, the results of this study suggest that the MSQ can be a useful screening tool.