Long-Term Trajectories of Posttraumatic Stress Disorder Symptoms: A 20-Year Longitudinal Study of World Trade Center Responders
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Objective
The present study examined the 20-year course of posttraumatic stress disorder (PTSD) in World Trade Center (WTC) responders to address four questions: (1) How stable are symptoms of PTSD? (2) What is the average symptom trajectory? (3) How much do responders differ from the average trend? (4) How quickly do PTSD symptoms improve or worsen?
Methods
Data include 81,298 observations from n = 12,822 responders, spanning from July 2002 to December 2022. Fourteen percent meet PTSD criteria. PTSD symptoms were measured using the PCL-17. Retest correlations were calculated to estimate stability, growth curve models to estimate individual trajectories, and Kaplan-Meier curves to estimate the rate of clinically significant change.
Results
Retest correlations were high overall (range =.49, .84), lower in PTSD cases (range =.21, .78), and decreased as a function of time between assessments. The best-fitting growth model represented trajectories continuously rather than multiple classes. Symptom burden peaked in 2011 and declined modestly by 2022 (Cohen’s d = -0.28 and -0.59 in all responders and PTSD cases, respectively). Median time before clinically significant improvement in responders with PTSD was 8.88 years (95% CI = 8.01, 9.79).
Conclusions
In the longest and largest study of PTSD symptoms tracked continuously since exposure, illness course was characterized to find that, while symptoms were highly stable in the short term, symptoms changed significantly over two decades. Most responders experienced clinical improvement after nine years, but 10% had poor course and should be the focus of public health efforts.
