Concurrent and Proximal Associations Among PTSD Symptoms, Prescription Opioid Use, and Co-Use of Other Substances: Results From a Daily Monitoring Study

Objective: Posttraumatic stress disorder (PTSD) and nonmedical prescription opioid use (NMPOU) are linked. Much of the research documenting this association uses cross-sectional or longitudinal designs that describe patterns of use over extended intervals. The present study used a daily monitoring design to examine how daily fluctuations in PTSD symptoms predicted patterns of prescription opioid use (both medical and nonmedical) and co-use of other substances. This approach has distinct advantages for understanding proximal temporal relations between PTSD symptom variation and substance use patterns. Method: Forty adults with clinical or subclinical PTSD and past-month NMPOU completed daily measures of PTSD symptoms, physical pain, prescription opioid use, and other substance use for 28 days using a smartphone application. Results: Same day co-use of prescription opioids and at least one other substance was common. Higher-than-typical PTSD symptoms on a given day (within-person) was associated with an increased likelihood of reporting NMPOU (overall and with co-use of one or more additional substances) on the same day. This association was specific to PTSD alterations in arousal and reactivity symptoms (Criteria E). Neither total PTSD symptoms nor individual PTSD symptom clusters prospectively predicted next-day prescription opioid use (overall or with co-use). Use of prescription opioids also did not predict next-day PTSD symptom severity. Conclusion: This is the first study to demonstrate positive associations between day-to-day fluctuations in PTSD symptoms and NMPOU. Results from the current study also highlight the importance of examining polysubstance use patterns among individuals with PTSD who use prescription opioids.