Most veterans treated at Headache Centers for Excellence in the Veterans Affairs (VA) health care system are designated as having a headache 'not otherwise specified (NOS)'— a catch-all diagnosis that may limit therapy options, researchers suggested in their presentation at the virtual annual scientific meeting of the American Headache Society.
The investigators wanted to determine differences in headache occurrence among the Headache Centers of Excellence based on comorbidities and gender.
About 16 percent of veterans were documented to have headache in at least one hospital code, creating a population of about 1.4 million individuals—and 85 percent of these headaches were classified as NOS, reported Jason J. Sico, MD, director of the Congressional-mandated Headache Centers of Excellence Research and Evaluation Center at the Veterans Health Administration, and director of the Headache Center of Excellence at the Veterans Affairs Connecticut Healthcare System in New Haven, CT.
"We were surprised that more than half of headache diagnoses fell into the category of headache-NOS," Dr. Sico told Neurology Today At the Meetings. "This could be for a myriad of reasons, including varying degrees of familiarity with the International Classification of Headache Disorders-third edition (ICHD-3) classification system or uncertainty about making a more specific headache diagnosis until additional evaluations such as brain imaging are completed."
About 36 percent of the patients with headache were classified as having migraine—the two classifications were not mutually exclusive, said Dr. Sico, who also is associate professor of neurology and of internal medicine at Yale School of Medicine.
Over the course of 10 years, the researchers also identified 71,344 cases of individuals with headache who had a history of traumatic brain injury. That represented about 5 percent of the total headache cohort. Headache with traumatic brain injury history was reported in 5.4 percent of the men and 2.6 percent of women in the study (p<0.0001), Dr. Sico said.
But even in this group, the diagnosis of headache-NOS predominated, he said, with 85 percent of both men and women with traumatic head injury receiving the headache-NOS diagnosis compared with 67.3 percent of the women (p<0.0001).
Post-traumatic headache was diagnosed in 43,184 veterans or 3 percent of cohort; and that included 3.2 percent men and 1.8 percent women, (p< .0001). About 16 percent of both sexes who experienced traumatic brain injury were also diagnosed with post-traumatic headache.
At least one non-headache pain condition was present in 90 percent of veterans with headache, with no gender difference. The most common comorbid pain conditions for both genders were limb pain (77.5 percent) and back pain (62.6 percent). Women had significantly higher rates of pelvic pain and systemic pain.
"We are now just understanding gender differences as they apply to headache among veterans," Dr. Sico said. "We found that women were more likely to be diagnosed with migraine than men. We know from decades of studies outside of the Veterans Health Administration that migraine occurs more commonly among women than men."
"We were also surprised by the low rate of post-traumatic headache within this population of veterans," he said. "We believe that the low post-traumatic headache rate can be partially explained by the current ICHD-3 definition that requires that post-traumatic headache begin within seven days of the head injury. As many headaches that appear later have the same characteristics as those appearing within seven days, perhaps a timeframe of within a year of injury, especially for persons leaving active duty and returning stateside following a traumatic brain injury, may be warranted."
"In considering both the high rates of headache NOS and low rates of post-traumatic headache, work is needed to assure that veterans get the best and most appropriate headache diagnosis," Dr. Sico added.
Commenting on the study, Peter Goadsby, MD, PhD, DSc, professor of neurology at King's College London, told Neurology Today At the Meetings, that the large percentage of men whose headaches were called 'not otherwise specified' or 'no specific cause' was disappointing.
"A headache diagnosis requires a history, so it is inexpensive, and there are good screening tools, such as ID-Migraine. The problem with headache-NOS is that there is no treatment. Diagnosis allows a treatment plan that will most often not involve simply using analgesics, so it is crucial to make a specific diagnosis as it is in the patients' best interest, noted Dr. Goadsby.
"One possible issue in the VA population is the predominance of men," Dr. Goadsby said. "Whereas migraine is more common in females in the population, and this is well known, it is possible this knowledge clouds the inclination to diagnose migraine in men. I would encourage the authors to study the NOS group as simply improving diagnosis is bound to improve their care."
Disclosures: Drs. Sico and Goadsby had no relevant disclosures.
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AHS Abstract: Fenton BT, Lindsey H, Grinberg A, et al. Prevalence of headache and comorbidities among men and women veterans across the Veterans Health Administration—A 10-year cohort study.