Predictors of post-traumatic stress disorder following critical illness: a mixed methods study
Ceri E Battle, Karen James, Tom Bromfield and Paul Temblett. Ed Major Critical Care Unit, Morriston Hospital, Swansea, Wales
The aim of this study was to investigate the predictors of PTSD in survivors of critical illness.
Research has suggested that PTSD commonly occurs in critical illness survivors, irrespective of specific pre-ICU admission trauma and a number of predictors of PTSD have been investigated. These include patient age, sex, pre-admission psychological illness, medications used during the ICU stay, delirium and others.
Patients attending the ICU Follow-up Clinic completed the UK- Post-Traumatic Stress Syndrome 14-Questions Inventory (UK-PTSS-14) and data was collected from their medical records. Predictors investigated included age, gender, Apache II score, ICU length of stay, pre-illness psychopathology; delirium and benzodiazepine administration during ICU stay and delusional memories of the ICU stay following discharge.
This study investigated the prevalence and predictors of PTSD in a heterogenous cohort of survivors of critical illness, treated on a general ICU. The prevalence of PTSD in this study was 27%, which is higher than the median value reported in the systematic review by Davydow et al (2008). This may be due, in part, to the patients in this study being attenders at the ICU follow-up clinic. It could be that patients with self-perceived, longer-term problems were more likely to attend the clinic, than those without. In a more recent review, pooled prevalences of clinically important posttraumatic stress disorder symptoms (95% CI) were demonstrated to be 25% (18-34%) and 44% (36-52%) using Impact of Event Scale thresholds, which is similar to that reported in this study.
The results of this study support previous research that younger survivors of critical illness patients are more likely to suffer with PTSD. Younger patients are more likely to receive aggressive interventions that may predispose them to the development of PTSD. Furthermore, older patients may have a higher number of comorbidities with more frequent admissions to hospital, so consequently do not perceive their ICU stay as stressful.
A lower illness severity was significantly associated with PTSD in this study. It could be suggested that patients with a lower illness severity are more likely to be more aware of the stressful ICU environment and more likely therefore to experience fear of poor outcomes, than patients who are less conscious or more heavily sedated. This study found that any pre-illness psychopathology (not specifically depression) was a significant predictor of PTSD.
Davydow DS, Gifford JM, Desai SV, Needham DM, et al. Posttraumatic stress disorder in general intensive care unit survivors: A systematic review. Gen Hosp Psychiatry. 2008;30:421–34
Griffiths J, Fortune G, Barber V, Young JD. The prevalence of post traumatic stress disorder in survivors of ICU treatment: A systematic review. Intensive Care Med. 2007;33:1506–18