Objectives: To describe the prevalence and persistence of headache and associated conditions in an inception cohort of U.S. veterans of Iraq and Afghanistan wars.

Background: Iraq and Afghanistan war veterans (IAV) suffer from persistent and difficult-to-treat headaches that have been found to co-occur with traumatic brain injury (TBI) and other deployment related comorbidities.

Methods: This longitudinal retrospective cohort study used data from the national Veterans Health Administration (VA) data repository for IAV who first received VA care in 2008 (baseline) and also received care each year in 2009, 2010, and 2011. We used ICD-9-CM codes, to identify those treated for headache each year (2008-2011). Individuals with headache diagnosed each year were classified as having persistent headache. We also identified comorbidities that may be associated with baseline headache using algorithms validated for use with ICD-9-CM codes. Comorbidities included TBI, posttraumatic stress disorder (PTSD), depression, and conditions associated with these diagnoses (anxiety, memory/attention/cognition, neck pain, tinnitus/hyperacusis, photosensitivity/photo blurring, insomnia, malaise/fatigue, and vertigo/dizziness). Multivariable logistic regression analysis was used to determine characteristics associated with baseline headache as well as those associated with persistent headache.

Results: Among all IAV, 38,426 received their first year of VA care in 2008 and had care each year 2009-2011: 13.7% of these were diagnosed with headache in 2008. Veterans diagnosed with headache in 2008 were more likely than those without a headache diagnosis to also have a diagnosis of TBI alone (adjusted odds ratios [AOR] 6.75; 95% CI 5.79-7.86), TBI + depression (AOR 7.09; 95% CI 5.23-9.66), TBI + PTSD (AOR 10.16; 95% CI 8.96-11.53), TBI + PTSD + depression (AOR 9.40; 95% CI 8.12-10.09), and neck pain (AOR 2.44; 95% CI 2.14-2.77). Among those with headache diagnosis in 2008, 24.3% had a headache diagnosis each of the subsequent years of care (persistent headache). While diagnoses of TBI, PTSD, and/or depression at baseline were not associated with headache persistence, persistence was more likely for individuals with baseline tinnitus/hyperacusis (AOR 1.21; 95% CI 1.02-1.45), insomnia (AOR 1.19; 95% CI 1.02-1.39), and vertigo/dizziness (AOR 1.83; 95% CI 1.30-2.57).

Conclusions: Our results indicate that TBI alone is a strong predictor of headache in the first year of VA care among IAV and that comorbid psychiatric comorbidities increase the likelihood of headache among individuals with TBI. However, among those with baseline headache, only tinnitus, insomnia, and vertigo were baseline clinical predictors of headache persistence. These results suggest that attention to other symptoms and conditions early in the diagnosis and treatment of headaches may be important for understanding prognosis. These comorbidities offer potential targets for intervention strategies that may help address postdeployment headaches.