Post-traumatic stress disorder (PTSD) is among the most prevalent anxiety disorders, both in terms of lifetime and 12-month prevalence rates documented in epidemiological studies worldwide. The National Comorbidity Survey Replication (NCS-R) study conducted in the USA, for example, found the lifetime prevalence of PTSD to be 6.8% while the 12-month prevalence was 3.5%. [1,2] The South African Stress and Health Study (SASH) documented lower lifetime (2.3%) and 12-month (0.6%) rates, although PTSD was among the anxiety disorders with the highest proportion of severe cases (36% of all individuals diagnosed with PTSD were severely ill).  High rates of PTSD (19.9%) have also been documented among South African patients attending primary healthcare clinics. 
2. Diagnosis and clinical characteristics
The disorder represents a pathological response to a traumatic event, characterised by symptoms of recurrent and intrusive distressing recollections of the event (e.g. nightmares, a sense of reliving the experience with illusions, hallucinations, or dissociative flashback episodes, intense psychological or physiological distress at exposure to cues that resemble the traumatic event); avoidance of stimuli associated with the trauma (e.g. inability to recall important aspects of the trauma, loss of interest, estrangement from others); and increased arousal (sleep disturbances, irritability, difficulty concentrating, hypervigilance, and exaggerated startle response).  These symptoms cut across three recognised symptom clusters (re-experiencing, avoidance or numbing and hyperarousal), produce distress and impairment for individuals, and form the essential targets for treatment. The Diagnositic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) includes an additional cluster of symptoms characterised by negative alterations in cognition and mood. The full symptom picture must be present for more than 1 month for the diagnosis to be made.  PTSD is classified in the category of trauma- and stressor-related disorders, and separate from the anxiety disorders, in the DSM-V. Risk factors that increase the likelihood of PTSD include severity of the traumatic exposure, history of past trauma or previous psychiatric disorder, female gender, experience of further stressful events and lack of social support.
As a general rule, a comprehensive review of the differential diagnosis of the anxiety symptoms should be done, ruling out or treating other psychiatric diagnoses and medical causes. Thus, as part of the initial diagnostic assessment, and after each subsequent treatment trial, should response to treatment be unsatisfactory, it is important to evaluate symptoms associated with PTSD (e.g. insomnia, aggression, nightmares, suicidality, psychotic symptoms). Other considerations include comorbid diagnoses (including depression, other anxiety disorders, substance abuse, bipolar disorder), other issues such as concurrent medical illness especially that which may be undiagnosed (e.g. thyroid disease), ongoing trauma, and legal/compensation issues, ongoing use of anxiety-producing substances (e.g. caffeine, other stimulants), pregnancy, and poor adherence to treatment.  Those with PTSD, with and without depression, are at increased risk for suicidality, and it is important to assess suicide risk both at the initial evaluation and subsequent follow-up visits. 
Longitudinal studies indicate that PTSD is a disorder of chronicity in that symptoms appear shortly after the traumatic event, subside in many individuals, but can persist in as many as 40% in the form of chronic PTSD.  Given that a significant number of cases of PTSD are undiagnosed and undertreated, it is important to inquire about exposure to trauma, and to maintain a high index of suspicion and a high level of awareness of the disorder. Patients with PTSD are frequent users of general medical and psychiatric services, have high rates of coexisting psychiatric (e. …