Suri P, Boyko EJ, Smith NL, et al. - Via a longitudinal cotwin control study of the Vietnam Era Twin Registry, researchers investigated the correlation of post-traumatic stress disorder (PTSD) symptoms with incident chronic back pain (CBP), while controlling for genetic factors and early family environment. The mean age was 62 years among 227 males completing 5-year follow-up, including 91 monozygotic twin pairs. Five-year incidence of CBP in those with baseline PTSD symptoms and without was 60% and 40%, respectively. In crude and multivariable-adjusted within-pair analyses, baseline PTSD symptoms were significantly related to incident CBP. Thus, PTSD symptoms had a relation with an raised incidence of CBP, without confounding by genetic factors or early family environment. Moreover, for prevention of CBP, PTSD symptoms may be a modifiable risk factor.