Abstract
STUDY OBJECTIVES: Posttraumatic stress disorder (PTSD) is associated with suicidal ideation (SI) and obstructive sleep apnea (OSA). There are no studies of OSA diagnosed by sleep study and SI in patients with PTSD. METHODS: Forty consenting civilians with PTSD (38 female, mean ± standard deviation age: 44.60 ± 12.73) underwent a Level 3 home sleep apnea test (WatchPAT200; Itamar Medical, Israel). OSA severity was measured with the respiratory disturbance index (RDI) (number of apneas, hypopneas and respiratory effort related arousals per hour). SI was measured with Items 9, 35, 39, and 50 of the Brief Symptom Inventory (BSI). Other patient-rated measures included the Beck Depression Inventory, second edition (BDI-II), PTSD Checklist for DSM-5 (PCL-5), and the Pittsburgh Sleep Quality Index PTSD Addendum modified to include only Items 1c, 1e, 1f, and 1g that address nightmares. RESULTS: The RDI (r = .757, P < .001) and oxygen desaturation index (r = .633, P < .001) were directly correlated to SI. Multiple regression analysis using SI as the dependent variable and patient-rated measures as independent variables revealed only RDI (β = .480, t = 4.167, P < .001) and BDI-II (β = .469, t = 3.375, P = .002) as predictors of SI, with adjusted R(2) = 0.718. In patients with RDI < 30 events/h (n = 37) correlation of SI with RDI (r = .511, P = .001) but not ODI (r = .312, P = .060) remained significant. Multiple regression analysis (when RDI < 30 events/h) revealed only BDI-II (β = .603, t = 3.492, P = .002), and not RDI (β = .247, t = 1.723, P = .096) as a significant predictor of SI. CONCLUSIONS: OSA severity in PTSD was directly related to SI. Depression was a significant mediator in the relationship between RDI and SI, with OSA-related intermittent hypoxemia possibly contributing to this relationship only in severe OSA.