Development of the Lebanese insomnia scale (LIS-18): a new scale to assess insomnia in adult patients.

Objective: To define the development and validation of the Lebanese Insomnia Scale (LIS-18) to be used for the evaluation of insomnia in Lebanese adult patients.
Methods: A first cross-sectional study, conducted between August 2017 and April 2018, enrolled 789 participants (sample 1). A second sample was recruited in May 2018 to confirm the results obtained from the first sample.
Results: Five factors derived from the LIS-18 scale items with an Eigenvalue over 1, explaining a total of 59.64% of the variance (Cronbach's alpha = 0.821). The first ROC curve, comparing participants with diagnosed insomnia to healthy individuals, showed that the optimal score was seen at a cutoff of 58.00, with a good sensitivity and specificity at this cutoff (93.3 and 88.4%, respectively). A second ROC curve, comparing participants taking drug medication for insomnia vs. those not taking drug, showed that the optimal score was seen at a cutoff of 52.50, with a good sensitivity and specificity at this cutoff (89.5 and 80.0%, respectively). A third ROC curve, comparing participants diagnosed by a physician or taking drug medication for insomnia and healthy control without insomnia drug, showed that the optimal score was seen at 51.50, with good sensitivity and specificity at this cutoff as well (90.0 and 78.10%, respectively). The positive predicted value (PPV) of the LIS-18 score in sample 2 was 93.3%, whereas the negative predicted value (NPV) was 88.4%.
Conclusion: The results demonstrate that the LIS-18 can be used in clinical practice and research to measure insomnia.