Use of the Sleep Apnea Scale of the Sleep Disorders Questionnaire (SA-SDQ) in adults with epilepsy

•The reliability of the SA-SDQ and its individual items for predicting OSA in adults with epilepsy was high.•The SA-SDQ total score and most items correlated strongly with the diagnosis of OSA and AHI (a marker of OSA severity).•A unique SA-SDQ cutoff score for both genders for any severity of OSA (25) and a cutoff score for moderate-to-severe OSA (28) are proposed.•Based on the sample prevalence of OSA of approximately 45%, PPVs and NPVs using these proposed scores are provided.

ObjectiveA growing body of literature supports the importance of sleep comorbidities in epilepsy. The prevalence of obstructive sleep apnea (OSA) in adults with epilepsy exceeds that of the general population, and its presence adversely impacts seizure control in some cases. The Sleep Apnea Scale of the Sleep Disorders Questionnaire (SA-SDQ) is a 12-item screening instrument generally used in clinical research. One prior study suggested modified cutoffs for the prediction of OSA in adults with epilepsy using this instrument. Our purpose was to further investigate the validity of the SA-SDQ in adults with epilepsy.MethodsNinety adults with epilepsy who underwent polysomnography (PSG) completed the SA-SDQ. Receiver operating characteristics were constructed to assess optimal sensitivity and specificity for predicting OSA (apnea-hypopnea index [AHI] ≥ 5).ResultsObstructive sleep apnea was diagnosed in 40 (44.4%) subjects. The overall area under the curve for the diagnosis of OSA was 0.771 (0.926 for males, 0.687 for females). For all subjects, a SA-SDQ cutoff score of 25 provided good sensitivity (73%) and specificity (72%) for OSA diagnosis. The same cutoff score provided optimal sensitivity (94%) and specificity (83%) for males, whereas for females, it provided lower sensitivity (55%) and specificity (68%). In females, a cutoff of 24 improved sensitivity (68%) but not specificity (58%). For all subjects with moderate-to-severe OSA (AHI ≥ 15), the area under the curve was 0.766, and the optimal cutoff was 28.SignificanceOur work confirms the validity of the SA-SDQ as a screening instrument for OSA in clinical research involving adults with epilepsy. Further, our findings support the use of cutoffs lower than those applied to the general population and a single cutoff score (25) for predicting any severity of OSA in adults with epilepsy.