Daily Variation in Suicidal Ideation in Individuals With and Without Posttraumatic Stress Disorder

ObjectiveLittle is known about the day-to-day variation in suicide ideation (SI) associated with posttraumatic stress disorder (PTSD). This study examined daily variations in SI frequency and intensity in individuals with and without PTSD. Methods: Using an ecological momentary assessment methodology, participants ( N  = 156; 78 with probable PTSD, 78 without PTSD) completed self-report assessments of SI four times daily for 15 days. SI was measured by Patient Health Questionnaire (PHQ-9) item 9. The SI assessment adherence rate was 80.0%. For each person, overall and daily measures of frequency of endorsing SI (FSI), mean SI intensity (MSI intensity; range 0-10), and highest SI intensity (HSI intensity; range 0-10) were obtained. Linear mixed models were used to examine associations between the 7 days of the week and weekday/weekend variations in FSI, MSI intensity, and HSI intensity and PTSD. Results: Individuals with PTSD (vs. those without) reported a higher overall FSI (23.2% vs. 2.0%, t  = 5.44, p  < .001), MSI intensity (1.01 vs. 0.04, t  = 4.17, p  < .001), and HSI intensity (3.26 vs. 0.87, t  = 4.97, p  < .001). Among those with PTSD and SI, 10.9% had overall MSI intensity scores between 5 and 10 (range 0-10) and 32.6% had overall HSI intensity scores of 8-10. Among the latter group, the overall HSI intensity was episodic for 60.0% and persistent for 40.0% of individuals. No day of the week or weekday versus weekend differences were found. Conclusions: Understanding the characteristics of SI frequency and intensity will aid in understanding the transition from SI to suicide attempts and may inform interventions and clinical care.