title: Risk factors for headache in the UK military: cross-sectional and longitudinal analyses.
abstract: OBJECTIVE
  To assess the importance of service demographic, mental disorders, and deployment factors on headache severity and prevalence, and to assess the impact of headache on functional impairment.
  
  
  BACKGROUND
  There is no information on prevalence and risk factors of headache in the UK military. Recent US reports suggest that deployment, especially a combat role, is associated with headache. Such an association may have serious consequences on personnel during deployment.
  
  
  METHODS
  A survey was carried out between 2004 and 2006 (phase 1) and again between 2007 and 2009 (phase 2) of randomly selected UK military personnel to study the health consequences of the Iraq and Afghanistan wars. This study is based on those who participated in phase 2 and includes cross-sectional and longitudinal analyses. Headache severity in the last month and functional impairment at phase 2 were the main outcomes.
  
  
  RESULTS
  Forty-six percent complained of headache in phase 2, half of whom endorsed moderate or severe headache. Severe headache was strongly associated with probable post-traumatic stress disorder (multinomial odds ratio [MOR] 9.6, 95% confidence interval [CI] 6.4-14.2), psychological distress (MOR 6.15, 95% CI 4.8-7.9), multiple physical symptoms (MOR 18.2, 95% CI 13.4-24.6) and self-reported mild traumatic brain injury (MOR 3.5, 95% CI 1.4-8.6) after adjustment for service demographic factors. Mild headache was also associated with these variables but at a lower level. Moderate and severe headache were associated with functional impairment, but the association was partially explained by mental disorders. Mental ill health was also associated with reporting moderate and severe headache at both phase 1 and phase 2. Deployment and a combat role were not associated with headache.
  
  
  CONCLUSIONS
  Moderate and severe headache are common in the military and have an impact on functional impairment. They are more strongly associated with mental disorders than with mild traumatic brain injury.
authors.affiliation: King's Centre for Military Health Research, Department of Psychological Medicine, King's College, London, UK. Roberto.rona@kcl.ac.uk
authors.forename: Roberto J
authors.initials: RJ
authors.lastname: Rona
authors.forename: Margaret
authors.initials: M
authors.lastname: Jones
authors.forename: Laura
authors.initials: L
authors.lastname: Goodwin
authors.forename: Lisa
authors.initials: L
authors.lastname: Hull
authors.forename: Simon
authors.initials: S
authors.lastname: Wessely
mesh_terms: D000328:Adult; D055826:Afghan Campaign 2001-; D001924:Brain Concussion / Q000150:complications / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006261:Headache / Q000453:epidemiology* / Q000209:etiology*; D006801:Humans; D054542:Iraq War, 2003-2011; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008889:Military Personnel / Q000523:psychology / Q000706:statistics & numerical data*; D015995:Prevalence; D012307:Risk Factors; D013313:Stress Disorders, Post-Traumatic / Q000150:complications / Q000453:epidemiology; D011795:Surveys and Questionnaires; D006113:United Kingdom; D055815:Young Adult