Identifying clinical and acute psychological risk factors for PTSD after critical care: a systematic review.

Background: Patients may suffer extreme psychological reactions in intensive care units (ICU), and post-traumatic stress disorder (PTSD) after leaving hospital. Previous systematic reviews of studies up to 2007 found that the true prevalence of and consistent risk factors for PTSD after ICU were not established, due to methodological shortcomings of studies. Therefore we aimed to conduct a systematic review of observational studies of post-ICU PTSD from 2008-2012, and to compare them to 1997-2007 studies, with regard to quality, prevalence estimates and risk factors.

Methods: We used a pre-specified protocol, and systematic, explicit methods to identify, select and critically appraise studies. Studies in general ICU settings with mixed-diagnosis patients (N.>30) were included. Risk of bias was assessed, with lower-risk studies given greater weight. No quantitative synthesis was possible due to heterogeneity, therefore ranges of estimates and frequencies of risk factors were examined.

Results: The review included 26 papers, 13 from 1997-2007 and 13 from 2008-2012. There were more high quality studies in the latter period. The range of prevalence estimates from high-quality studies was similar; 8% to 27% (1997-2007) and 9% to 27% (2008-2012). Clinical risk factors consistently identified over the two periods were use of benzodiazepines, duration of sedation and mechanical ventilation. Psychological risk factors include stress and fear experienced acutely in ICU, and frightening memories of the admission.

Conclusion: The quality and number of post-ICU PTSD studies has increased over time, and we can be more confident in the accumulated findings. Evidence from both periods suggests that up to 27% of ICU survivors suffer from PTSD. There is also increasing evidence that use of benzodiazepines and duration of sedation, along with fear, stress and delirium in the ICU are likely risk factors for subsequent PTSD.