Associations of initial injury severity and posttraumatic stress disorder diagnoses with long-term hypertension risk after combat injury

The associations between injury severity, posttraumatic stress disorder (PTSD), and development of chronic diseases, such as hypertension, among military service members are not understood. We sought to (1) estimate the prevalence and incidence of PTSD within a severely injured military cohort, (2) assess the association between the presence and chronicity of PTSD and hypertension, and (3) determine whether or not initial injury severity score and PTSD are independent risk factors for hypertension. Administrative and clinical databases were used to conduct a retrospective cohort study of 3846 US military casualties injured in the Iraq and Afghanistan conflicts between February 1, 2002, and February 1, 2011. Development of PTSD and hypertension after combat injury were determined using the International Classification of Diseases, Ninth Revision codes. Multivariable competing risk regression models were used to assess associations between injury severity score, PTSD, and hypertension, while controlling for covariates. Overall prevalence of PTSD was 42.4%, and prevalence of hypertension was 14.3%. Unadjusted risk of hypertension increased significantly with chronicity of PTSD (1-15 diagnoses: hazard ratio, 1.77; 95% confidence interval, 1.46-2.14; P<0.001; >15 diagnoses: hazard ratio, 2.29; 95% confidence interval, 1.85-2.84; P<0.001) compared with patients never diagnosed with PTSD. The association between injury severity score (hazard ratio, 1.06 per 5-U increment; 95% confidence interval, 1.03-1.10; P<0.001) and hypertension was significant, with little change in effect in the multivariable model (hazard ratio, 1.05 per 5-U increment; 95% confidence interval, 1.01-1.09; P=0.03). In a cohort of service members injured in combat, we found that chronicity of PTSD diagnoses and injury severity were independent risk factors for hypertension.