Use of a screening questionnaire for post-traumatic stress disorder (PTSD) on a sample of UK ICU patients

Background: Although rates vary across studies, research in recent years shows that prevalence of post-traumatic stress disorder (PTSD) following intensive care unit (ICU) can be high. Presently no screening tool assessing all three PTSD symptom categories has been validated in ICU patients. The aim of the study was to conduct a preliminary validation of such a measure, the UK- Post-Traumatic Stress Syndrome 14-Questions Inventory (UK-PTSS-14). Methods: A case series cohort study performed at two ICUs in two UK district general hospitals. The UK-PTSS-14 was administered at three time-points (4-14 days, 2 months and 3 months post-ICU discharge). At time-point three participants also completed the Post-traumatic Stress Diagnostic Scale (PDS) and the Impact of Events Scale (IES). Results: Forty-four patients completed the 3-month follow up. The UK-PTSS-14 was internally reliable at all three time-points (Cronbach's alpha=0.89, 0.86 and 0.84, respectively). Test-retest reliability was highest between time-points two and three (ICC=0.90). Concurrent validity at time-point three was high against the PDS (r=0.86) and the IES (r=0.71). Predictive validity was highest at time-point two (r=0.85 with the PDS and r=0.71 with the IES). Receiver operator characteristic curve analysis suggested the highest levels of sensitivity (86%) and specificity (97%) for diagnosis of PTSD were at time-point two, with an optimum decision threshold of 45 points. Conclusion: This preliminary validation study suggests that the UK-PTSS-14 could be reliably used as a screening instrument at 2 months post-discharge from the ICU to identify those patients in need of referral to specialist psychological services.