[1][2] The term does not replace any individual diagnoses or disorders, but rather describes a category of mental health concerns linked to the particular challenges that these military members or first responders encounter in their service.
[2] OSI encompasses a number of the diagnoses found in the Diagnostic and Statistical Manual of Mental Disorders (DSM) classification system, with the common thread being a linkage to the operational experiences of the afflicted.
[4] The term, at present mostly used within Canada, is increasingly significant in the development of legislation, policy, treatments and benefits in the military and first responder communities.
[7] The term was designed to expand the understanding of mental health disorders related to service beyond just PTSD, and to include other clinical diagnoses linked to trauma.
[8] By 2016, the Canadian Parliamentary Standing Committee on Public Safety and National Security recognized OSIs as an issue faced by all first responder organizations, not just the military.
[4] As of late 2016, the Parliament of Canada is exploring a national strategy to address OSIs within the various public safety professions.
[2][4] Research within the Canadian military has nonetheless identified several disorders most commonly associated with traumatic service-related experiences, and which have generally been accepted as included in the term.
[11] Posttraumatic stress disorder, or PTSD, is among the most common individual diagnoses linked to traumatic exposure in military or first responder service.
[13] When PTSD is totalled with other anxiety disorders, this category of mental health diagnosis is the most prevalent among Canadian military personnel with deployments[9] A lesser known but not uncommon diagnosis among military personnel,[9] adjustment disorder (sometimes referred to as situational depression) is characterized by an individual's inability to adjust to external stressors, or major life events.
Although presentation will vary, it may include a combination of depressive, anxious, or post-traumatic stress symptoms that do not meet the clinical threshold for those related named disorders.
In addition to formal healthcare settings, numerous grassroots or state-funded peer support organizations have emerged.