title: Mental health consequences of overstretch in the UK Armed Forces, 2007-09: a population-based cohort study.
abstract: BACKGROUND
  Concerns have been raised about the effect of tour length on the mental health of the UK armed forces. In 2007, we reported that cumulative length of deployment was associated with mental illness in military personnel. Our findings provided empirical evidence to support the UK advisory policy for tour length, known as the Harmony Guidelines. If fully implemented, these guidelines could aid prevention of mental illnesses. We aimed to reassess the association between cumulative length of deployment and number of deployments with mental illness in the UK forces.
  
  
  METHODS
  Our analysis was based on data from a representative study of the military for UK regular personnel who had completed a questionnaire between Nov 2, 2007, and Sept 24, 2009, and were deployed in the 3 years before questionnaire completion. Study outcomes were presence of possible post-traumatic stress disorder (PTSD), psychological distress, multiple physical symptoms, alcohol misuse, problems at home during and after deployment, and relationship or family problems. The key independent factors were deployment for 13 months or more, and months and number of deployments in the past 3 years.
  
  
  RESULTS
  8278 regulars responded to the questionnaire, of whom 3982 (48%) had been deployed in the 3 years before questionnaire completion. Deployment for 13 months or more decreased from 22% in March, 2005, (median March 8, 2005 [IQR Oct 10, 2004 to April 28, 2005]), to 12% in May, 2008, (May 17, 2008, [Feb 14, 2008, to Dec 5, 2008]). We noted an association between cumulative time deployed as a continuous variable and a score of 40 or more on the PTSD checklist (p=0·002), presence of psychological distress (p=0·018), and multiple physical symptoms (p=0·030; table 2). Furthermore, 13 months or more of deployment was associated with multiple physical symptoms (adjusted odds ratio [OR] 2·15, 95% CI 1·39-3·32), a PTSD checklist score of 40 or more (2·02, 1·31-3·12), and problems at home, but not a PTSD checklist score of 50 or more (1·50, 0·82-2·75), psychological distress 1·34, 0·98-1·85), or alcohol misuse (1·32, 0·97-1·80). Number of deployments was not associated with worse mental illness status or problems at home.
  
  
  CONCLUSIONS
  The Harmony Guidelines can prevent mental illness in the UK Armed Forces and, since 2006, their introduction has prevented personnel from being deployed for a longer period than recommended in the guidelines. Monitoring of cumulative length of deployment might reduce mental illness in the UK military.
  
  
  BACKGROUND
  The UK Ministry of Defence.
authors.affiliation: King's Centre for Military Health Research, Department of Psychological Medicine, King's College London, Weston Education Centre, London, UK. Electronic address: Roberto.rona@kcl.ac.uk.
authors.forename: Roberto J
authors.initials: RJ
authors.lastname: Rona
authors.affiliation: King's Centre for Military Health Research, Department of Psychological Medicine, King's College London, Weston Education Centre, London, UK.
authors.forename: Margaret
authors.initials: M
authors.lastname: Jones
authors.affiliation: King's Centre for Military Health Research, Department of Psychological Medicine, King's College London, Weston Education Centre, London, UK.
authors.forename: Mary
authors.initials: M
authors.lastname: Keeling
authors.affiliation: King's Centre for Military Health Research, Department of Psychological Medicine, King's College London, Weston Education Centre, London, UK.
authors.forename: Lisa
authors.initials: L
authors.lastname: Hull
authors.affiliation: King's Centre for Military Health Research, Department of Psychological Medicine, King's College London, Weston Education Centre, London, UK.
authors.forename: Simon
authors.initials: S
authors.lastname: Wessely
authors.affiliation: Academic Department of Military Mental Health, Department of Psychological Medicine, King's College London, Weston Education Centre, London, UK.
authors.forename: Nicola T
authors.initials: NT
authors.lastname: Fear