Posttraumatic stress disorder (PTSD) after hospitalisation has been increasingly acknowledged over the last decade. In particular, intensive care treatment may lead to PTSD in the same way as war and other life-threatening situations, although not as frequently.1–4 The resulting psychological damage and its impact on long-term outcome is evident.5
Posttraumatic stress impacts heavily on quality of life and can, therefore, exert an influence on the outcome of other maladies.6,7 For instance, PTSD is a risk factor for cardiac events and it is associated with a higher suicide risk.8,9 Early PTSD detection is critical for rapid intervention such as trauma-focused cognitive behavioural therapy or eye movement desensitisation and reprocessing.10–13 Although there is a chance of full recovery, chronic PTSD is common, with subsequent changes of some traits of personality making treatment far more difficult.5,14–16
According to the International Classification of Diseases (ICD) and the Diagnostic and Statistical Manual of Mental Disorders (DSM), PTSD symptoms occur with some delay after the traumatic event and, when present, they have to persist for at least 1 month to meet the diagnostic criteria. In addition to typical anxiety disorder related symptoms, distinctive symptoms include intrusive experiences (nightmares, ‘flash-backs’) in which patients re-experience the traumatising events. Twigg et al.17 developed the PTSS-14 (Post-Traumatic Stress Syndrome 14-Questions Inventory) to screen patients for PTSD in clinical practice. The wide use of this questionnaire makes results comparable and may lead to a significant increase in reliable information in this area of research. PTSS-14 was translated for use in the German-speaking setting and has passed a validation process.18
Medical interventions, and in particular intensive care treatment, have been examined in several studies and clinical trials as a trigger for PTSD.19–22 Possible risk factors include myocardial infarction, acute respiratory distress syndrome (ARDS) as well as the experience of being treated on an ICU.23–25 Reported incidences vary from 4% following myocardial infarction to 27.5% following acute respiratory failure and 27% after intensive care treatment in general.19,23,25 Data concerning prevalence of, and risk factors for, PTSD following surgery are missing or are at the very best rudimentary.26
We hypothesised that postoperative delirium could be a risk factor for PTSD 3 months after surgery. Delirium is associated with an increased mortality rate and is independently associated with cognitive decline at hospital discharge and 6 months after surgery.27 Delirium involves a state of confusion with impaired orientation, which is fluctuating and can present itself in a hyperactive, hypoactive or mixed form. Delirious patients require a longer time for cognitive recovery than those without delirium. Studies on elderly postoperative noncardiac patients revealed a 40% prevalence of postoperative delirium.27,28
The objective of this study was to measure the prevalence of PTSD in elderly patients 3 months after surgery with general anaesthesia. Furthermore, risk and protective factors associated with PTSD 3 months after surgery were sought.
Materials and methods
Ethical approval for this prospective clinical study (ethics proposal number EA1242/08) was obtained from the Ethical Committee of Charité - Universitätsmedizin Berlin, Germany (Chairperson Prof. Dr med. Ralf Uebelhack) on 9 March 2009. The study was conducted parallel to the main focus of a study on the use of monitoring depth of anaesthesia in relation to cognitive dysfunction and postoperative delirium. These results were not used for the analysis in this article and have already been published.29
All patients undergoing elective noncardiac surgery in Charité Campus Virchow-Klinikum and Campus Charité Mitte between March 2009 and May 2010 were evaluated for inclusion in the SuDoCo study (Surgery Depth of anaesthesia Cognitive outcome). All patients undergoing elective surgery under general anaesthesia were included following informed consent and all noncardiac surgical specialties were considered. Inclusion criteria were a minimum age of 60 years and an estimated duration of surgery of more than 60 min under general anaesthesia. The type of surgery was not individually analysed; the focus was on the duration of anaesthesia. A wide range of types of surgery were included, covering almost all fields. Exclusion criteria were impaired cognitive function [mini-mental state examination (MMSE) score of less than 24], simultaneous participation in drug trials and nonproficiency in German language. Written informed consent was obtained from all participating patients.
Throughout the study the ‘gold-standard’ for diagnosing PTSD was the criteria defined by the DSM-IV (4th Diagnostic and Statistical Manual of Mental Disorders). A new version of the DSM, the DSM-V, has recently been published. Alternatively, ICD-10 (10th International Classification of Diseases) criteria can be applied.4,15,16 In both the ICD and the DSM, the key criterion (DSM-IV A criterion) and trigger for PTSD is the exposure to a traumatic event involving loss of ‘physical integrity’, or risk of serious injury or death to self (or others). In addition to the exposure to a potentially traumatic event, the ICD also requires an acute emotional response to the event such as intense fear, horror, helplessness or despair. This has been modified by the DSM-V in that an emotional response is no longer necessary; there is also no longer a distinction between acute and chronic PTSD.
For assessing PTSD symptoms, participants completed the PTSS-14 which consists of 14 questions. Patients were asked to rate their answers on a 7-point Likert Scale (1, never to 7, always) resulting in a total score between 14 and 98. Higher scores represent a more likely diagnosis of PTSD. PTSS-14 was originally created by Twigg et al.,17 and was recently translated and validated for use in German-speaking countries (D-PTSS).18 The validated D-PTSS-14 showed high sensitivity (82%) and specificity (92%) with the optimum cut-off point at 40 points.18 While completing the questionnaire, patients were asked to refer to the stay in hospital following general anaesthesia.
Participating patients were screened with the PTSS-14 scale for PTSD 3 months after surgery. In addition, a small number of patients (n = 138) were screened 7 days after the procedure in order to evaluate the possibility of early screening. Screening for postoperative delirium was conducted using the confusion assessment method (CAM) twice in the recovery room (10 and 60 min after surgery) and twice daily for the following 7 days.30 The CAM was developed by Inouye in 1990. It was developed for patients in non-ICU departments, has been used in a wide range of clinical studies and has been translated and validated in several languages. The detection of at least one episode of postoperative delirium was defined as a positive postoperative delirium screening. Postoperative nausea and vomiting (PONV) were recorded in the recovery room and in the ICU 60 min after surgery.
In addition, patients were asked to complete the WHO-5 depression assessment preoperatively. The WHO-5 depression assessment uses a short questionnaire that allows screening for depressive symptoms. The cut-off point for screening positive was a score of less than 8.31 Postoperative pain scores (numerical rating scale from 0 to 10) were also recorded twice a day.
Univariate statistical analysis was performed by means of cross-tabulation including Fisher's exact test and nonparametric Mann–Whitney U-test comparing two groups, PTSD 3 months after surgery positive and negative, respectively. The statistical level of significance was defined at P value less than 0.05.
In order to identify associations between PTSD 3 months after surgery and other factors, multivariate backward logistic regression analysis was performed. A total of 411 patients were included in the multivariate regression, missing values limiting the inclusion of all patients. Factors included in the multivariate regression were selected partly due to significance in the univariate calculations and partly for clinical reasons. Eight variables were included: postoperative pain in the recovery room; positive preoperative depression according to the WHO-5 depression score; age; American Society of Anesthesiologists’ (ASA) physical status; gender; duration of anaesthesia; postoperative delirium; and PONV. The calculation included stepwise backward selection to find the relevant parameters significantly associated with PTSD 3 months after surgery. Furthermore, for each factor included, odds ratios with 95% confidence intervals and the corresponding P values were calculated.
Participants and descriptive data
One thousand two hundred and seventy-seven patients were recruited; 559 patients completed the PTSS-14 questionnaire 3 months after surgery and were included (Fig. 1). Patient characteristics and perioperative data are summarised in Table 1.
Outcome data and main results
Sixty-six patients (12%) had PTSD based on the PTSS-14 questionnaire 3 months after surgery. Seventy-seven patients (14%) had postoperative delirium.
In the univariate analysis, the following associations with PTSD 3 months after surgery were identified: PTSS-14 score 7 days after surgery; postoperative delirium; postoperative pain; PONV; and preoperative depression (negative association) (Table 1).
Independent associated factors in the backward logistic regression were postoperative delirium (risk factor) and preoperative depression (protective factor) (Table 2).
The main result of this study was the high prevalence of PTSD 3 months after surgery in elderly patients undergoing general anaesthesia. A second key result was the observation that postoperative delirium was a risk factor for PTSD 3 months after surgery.
The prevalence of PTSD that we identified 3 months after surgery could be a realistic estimate of an overall prevalence based on the fact that a wide variety of patients from different surgical specialties were included. The high prevalence of 12% may nevertheless still be an underestimation of the ‘true’ prevalence because patients with the most severe form of PTSD 3 months after surgery are less likely to complete all stages of the screening process.32
An important result of our study was that postoperative delirium was independently associated with PTSD 3 months after surgery. Sensory misperceptions, illusions and a feeling of disorientation as well as irrational thoughts are likely stress factors leading to a traumatic experience and possibly to a subjectively perceived threat to life.3,30 Thus, postoperative delirium may reinforce the subjective experience of a life-threatening event, even when there is, in reality, no particular threat to life. Consequently, patients with postoperative delirium may process the time after surgical procedures in the same way as an actual threat, leading to similar consequences.3,33 These findings underline the utmost importance of timely diagnosis and treatment of postoperative delirium.
We also showed that there is a univariate association between the PTSS-14 score 7 days postoperatively and PTSD 3 months after surgery when measured using the PTSS-14 questionnaire. It may be reasonable to screen all patients prior to discharge even though PTSD cannot be diagnosed at this early stage according to DSM and ICD.14–16 For this reason, the actual scores were compared rather than comparing the PTSD-positive versus PTSD-negative outcomes of the questionnaire. Considering the difficulty of reaching every patient 3 months after discharge, early screening, although not entirely reliable, may be a reasonable compromise. The screening process itself is easy to execute and very quick to analyse, and enables early intervention, potentially reducing the number of patients who develop chronic PTSD.5,17,18
An interesting result was that a positive preoperative WHO depression score seemed to result in a significantly lower risk of developing PTSD 3 months after surgery (P < 0.001). This is very interesting because other studies have found different tendencies.34 We speculate that PTSD 3 months after surgery may require a particular physiological response and susceptibility to emotional stress. The emotional numbness that can be a part of depression may reduce this susceptibility. The overall negative expectations may contribute differently to the experience of medical interventions. Further investigation may be needed in this area.35
Statistical association does not equate with causality. Therefore, the association between postoperative delirium and PTSD may not be causal and should not be overinterpreted. Further studies are needed to reinforce this observation.
Patients admitted to this study were exclusively over 60 years of age. Although it is probable that the risk factors are equal in all age groups, this needs further evaluation in future studies. Furthermore, only 559 of all patients (1277 in total) were included in this part of the study. This was due to the prolonged evaluation process of the questionnaire used, as well as a high drop-out rate at 3 months.
No distinction was made in the analysis between the different types of anaesthetics used, or between the different types of surgery. Although this has no influence on the connection between PTSD 3 months after surgery and postoperative delirium, it may have an influence on prevalence. This investigation was a single-centre study; therefore, our results cannot be generalised.
Finally, the target number of patients to be included in the study (1600) was not achieved. This was due to a lack of funding and, therefore, no possibility of prolonging the length of the study.
This study identified a high prevalence of PTSD 3 months after surgery and found that postoperative delirium was a risk factor for PTSD 3 months after surgery. On the basis of the results of this study, we recommend screening for PTSD after surgery.
Acknowledgements relating to this article
Assistance with the study: none.
Conflicts of interest: none.
Financial sponsorship and support: this work was supported by grants from the Charité - Universitätsmedizin Berlin, Berlin, Germany.
Presentation: preliminary data from this study were presented as a poster presentation at the European Delirium Association 18 to 19 October 2012, Bielefeld.
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