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Subthreshold PTSD contributes to future disorder burden in military

Study findings published in Depression & Anxiety showed that subthreshold PTSD accounted for a large proportion of a representative military cohort’s future PTSD burden.

“Despite the large number of papers that have documented the prevalence of subthreshold PTSD, to the best of our knowledge only a single study has examined the longitudinal course of subthreshold PTSD and no longitudinal studies have been conducted in a military setting,” David S. Fink, MPH, from the department of epidemiology at Columbia University’s Mailman School of Public Health, and colleagues wrote.

The researchers evaluated the role of subthreshold PTSD and probable PTSD on future PTSD in a representative military cohort of 3,457 U.S. National Guard members from Ohio. Fink and colleagues calculated the exposure rate, risk ratio and population attributable fraction to determine the burden of future probable PTSD attributable to subthreshold PTSD compared with probable PTSD.

Participants were assessed via phone each year from 2008 to 2014, then were classified into one of three groups at each wave based on the PTSD Checklist: no PTSD, probable PTSD, and subthreshold PTSD — defined as having at least one symptom in each cluster, symptom lasting longer than 30 days and functional impairment.

The researchers found that the yearly prevalence was 11.9% for subthreshold PTSD and 5% for probable PTSD. Although the risk ratio for probable PTSD was higher among respondents with probable PTSD at the prior interview than that of those with subthreshold PTSD (7 vs. 3.4), the population attributable fraction was much greater in those with subthreshold PTSD at the previous interview (35%; 95% CI, 26-42.9) than in those with probable PTSD (28%; 95% CI, 21.8-33.8).

“Our findings that respondents with subthreshold PTSD had an increased risk of future PTSD as compared to persons without PTSD, suggests a need to move beyond a binary PTSD diagnosis,” Fink and colleagues wrote.

“The elevated risk for future PTSD among those with subthreshold PTSD — combined with our finding that persons with subthreshold PTSD contribute more to the future population burden of probable PTSD than persons with chronic PTSD — suggests that it is important to include persons with subthreshold PTSD into intervention dissemination efforts and clinical care,” they continued. “Treatment for persons who go on to develop PTSD can receive current evidence-based PTSD care; however, research is needed to identify when and how to best treat those with subthreshold PTSD.” – by Savannah Demko

Disclosure: The authors report no relevant financial disclosures.