This investigation of nearly 1,500 ICU survivors highlights that symptoms suggestive of PTSD occur in one-quarter one year after their ICU stay. The point prevalence of symptoms suggestive of a diagnosis of PTSD in this cohort is similar to the findings of studies of general ICU survivors [6
]. In addition, less than half of the patients requiring ICU stays for traumatic injury returned to their usual major activity (i.e., work, school, homemaker, etc.) 12 months after hospital discharge.
The findings regarding predictors of PTSD and return to usual major activity corroborate and extend those of prior investigations [10
]. As with prior analyses of the NSCOT data that focused on the prediction of 12-month PTSD in all trauma survivors, early psychological and physical distress symptoms predicted 12-month PTSD symptoms. However, above and beyond early post-ICU symptoms of distress, PAC insertion predicted PTSD symptoms, and a longer ICU LOS and having a tracheostomy were associated with limitations in return to usual major activity. To our knowledge, this study is the first large-scale investigation of ICU survivors to find an association between PAC insertion and post-ICU psychiatric morbidity. PAC insertion in this sample could be a proxy for injury/illness severity, since PA catheterization is indicated in critically ill patients requiring intensive hemodynamic monitoring [24
]. Furthermore, if PAC insertion represents greater illness/injury severity, then systemic inflammation could serve as an underlying pathophysiologic mechanism for the development of subsequent PTSD symptoms. Severe traumatic injuries are associated with activation of inflammatory cascades [25
], and inflammation has been speculated to play a role in the etiology of post-ICU PTSD [27
]. Moreover, critically ill patients are at greatly increased risk for delirium [28
], and in-ICU delirium may confer vulnerability for post-ICU PTSD [6
]. Since PAC insertion is an invasive procedure, it could represent an additional psychological trauma for the patient that may predispose to later psychopathology. Invasive procedures have been found to be associated with PTSD in pediatric intensive care survivors [29
], and our findings suggest that a similar association may be true in adults.
Additionally, pre-ICU depression was a predictor of symptoms suggestive of a diagnosis of PTSD 12 months after hospitalization. This finding bolsters the evidence suggested in general ICU populations that pre-ICU psychopathology is an important risk factor for psychiatric morbidity months after ICU stays [6
Substantial pre-ICU medical co-morbidities were found to be a risk factor for post-ICU PTSD in our cohort, an unsurprising finding as chronic medical illnesses are known to be associated with anxiety disorders [30
]. Contrary to prior investigations of adult survivors of physical injuries [33
], our investigation did not find female gender to be associated with an increased risk of developing PTSD symptoms following an ICU stay for traumatic injury. Also, to our knowledge, the current study is the first to demonstrate that female ICU survivors were more likely to return to usual major activity, in contrast to a prior study of physical injury survivors which found that women were less functional post-injury [35
], and prior studies of ICU survivors which found no significant differences in function based on gender [36
Several important limitations of the current study should be noted. First, many pre-ICU characteristics, including pre-ICU depression, were assessed retrospectively by patient report at the 3-month post-injury interview, potentially introducing bias due to current levels of distress and impairment. Second, the model used may have been overly conservative; including early post-ICU psychological and physical distress may have weakened the impact of analyses of other factors, such as pre-ICU depression or ICU and acute care service-related characteristics, on the outcomes. Third, the population described in this study is comprised entirely of survivors of traumatic injury, and although the outcomes were not influenced by injury severity, the study's findings may not be generalizable to other critically ill populations. Fourth, data on other ICU service-delivery characteristics of potential interest such as specific sedatives administered or exposure to corticosteroids was not collected in this study. Fifth, since a questionnaire, and not a structured or semi-structured diagnostic interview, was used to assess PTSD symptoms post-ICU, a diagnosis of PTSD could not be made, hence the use of the phrase, “symptoms suggestive of the diagnosis of,” throughout to articulate that the level of symptoms reached the questionnaire threshold for probable diagnosis. Furthermore, post-ICU return to usual major activity was measured by a single general question, limiting the depth of understanding of this important functional measure. Finally, the multiple imputation method has limitations, as do all methods attempting to handle missing data [37
In conclusion, patients surviving ICU stays for traumatic injury are burdened by substantial PTSD symptoms, and more than half do not return to usual major activity such as work or school 12 months after hospital discharge. ICU and acute care service-delivery characteristics such as PAC insertion may increase the risk of PTSD, and prolonged ICU LOS and having a tracheostomy may diminish usual major activity. Pre-ICU substantial medical co-morbidities and pre-ICU depression may increase the risk of post-ICU PTSD. Patients surviving ICU stays for traumatic injury who meet these risk factor profiles should be identified early so that they can receive appropriate treatments if necessary, and future investigations should be geared toward early screening and preventive interventions in acute care settings that may avert the suffering caused by subsequent psychiatric morbidity and impairments in function.