A longitudinal cotwin control study of the Vietnam Era Twin Registry.
The aim of this study was to examine the association of post-traumatic stress disorder (PTSD) symptoms with incident chronic back pain (CBP), while controlling for genetic factors and early family environment.
It is unknown whether PTSD symptoms are associated with an increased incidence of CBP.
In 2010 to 2012, a baseline survey was undertaken as part of a large-scale study of PTSD. Study participants completed the PTSD Symptom Checklist (PCL) and a self-report measure of CBP. In 2015 to 2017, a follow-up survey was sent to all 171 monozygotic (MZ) twin pairs (342 individuals) where both cotwins had no history of CBP at baseline, but only one cotwin in the pair met criteria for having current PTSD symptoms (one twin with PCL <30 and the cotwin with PCL ≥30). No other inclusion/exclusion criteria were applied. CBP at 5-year follow-up was defined as back pain of duration ≥3 months in the low back or mid/upper back. Covariates included age, race, education, income, Veterans Affairs health care use, disability compensation, smoking, body mass index, and depression. Statistical analysis estimated the cumulative incidence of CBP according to baseline PTSD symptoms. Risk ratios (RRs) and 95% confidence intervals (95% CIs) were estimated in matched-pair cotwin control analyses adjusting for familial factors.
Among 227 males completing 5-year follow-up, including 91 MZ twin pairs, the mean age was 62 years. Five-year incidence of CBP in those without and with baseline PTSD symptoms was 40% and 60%, respectively. Baseline PTSD symptoms were significantly associated with incident CBP in crude and multivariable-adjusted within-pair analyses (RR 1.6, 95% CI 1.2–2.1; P = 0.002).
PTSD symptoms were associated with an increased incidence of CBP, without confounding by genetic factors or early family environment. PTSD symptoms may be a modifiable risk factor for prevention of CBP.
Level of Evidence: 3
In this first longitudinal cotwin control study of post-traumatic stress disorder and chronic back pain, post-traumatic stress disorder symptoms were associated with incident chronic back pain at 5-year follow-up, independent of genetic and familial factors. Post-traumatic stress disorder symptoms may be a modifiable risk factor for chronic back pain.
∗Seattle Epidemiologic Research and Information Center, VA Puget Sound Health Care System, Seattle, WA
†Division of Rehabilitation Care Services, VA Puget Sound Health Care System, Seattle, WA
‡Department of Rehabilitation Medicine, University of Washington, Seattle, WA
§Clinical Learning, Evidence and Research (CLEAR) Musculoskeletal Research Center, University of Washington, Seattle, WA
¶General Medicine Service, VA Puget Sound Health Care System, Seattle, WA
||Department of Epidemiology, University of Washington, Seattle, Seattle, WA
∗∗Departments of Radiology, Neurological Surgery and Health Services, University of Washington, Seattle, WA
††Department of Medicine (Medical Genetics), University of Washington, Seattle, WA
‡‡Department of Genome Sciences, University of Washington, Seattle, WA
§§Department of Twin Research and Genetic Epidemiology, Kings College London, London, UK.
Address correspondence and reprint requests to Pradeep Suri, MD, MS, Division of Rehabilitation Care Services/Seattle Epidemiologic Research and Information Center (ERIC), VA Puget Sound Healthcare System, 1660 S. Columbian Way, Seattle, WA 98108; E-mail: firstname.lastname@example.org
Received 9 August, 2018
Revised 26 January, 2019
Accepted 11 March, 2019
The manuscript submitted does not contain information about medical device(s)/drug(s).
The creation and the ongoing development, management, and maintenance of the Vietnam Era Twin (VET) Registry (CSP #256) is supported by the Cooperative Studies Program (CSP) of the United States Department of Veterans Affairs (VA) Office of Research & Development. VET Registry data included in this article was supported by funding for CSP #569: The Course and Consequences of PTSD in Vietnam Era Twins, and a Career Development Award #1IK2RX001515 from VA Rehabilitation Research and Development.
All statements and opinions are solely of the authors and do not necessarily reflect the position or policy of the VET Registry, the VA, or the United States Government.
Relevant financial activities outside the submitted work: board membership.