Postoperative delirium is an independent risk factor for posttraumatic stress disorder in the elderly patient: a prospective observational study

Abstract

Background: Posttraumatic stress disorder (PTSD) may appear after hospitalisation for surgery with general anaesthesia in elderly patients. Prevalence and risk factors in this setting are unknown. Postoperative delirium could be a risk factor.

Objective: The purpose of this study was to identify the prevalence of, and risk factors for, PTSD 3 months after surgery with general anaesthesia in elderly patients.

Design: A prospective, clinical observational study.

Setting: This study was carried out between March 2009 and May 2010 in a German university hospital in Berlin and was part of a larger study focusing on depth of anaesthesia.

Inclusion criteria: at least 60 years of age; noncardiac surgery with general anaesthesia.

Exclusion criteria: impaired preoperative cognitive function [mini-mental state examination (MMSE) score <24]; expected surgery time less than 1 h; nonproficiency in the German language.

Interventions: None.

Main outcome measures: Screening for PTSD 3 months after surgery using the screening instrument Post-Traumatic Stress Syndrome 14-Questions Inventory Score (PTSS-14). The following risk factors for PTSD 3 months after surgery were tested: age; American Society of Anesthesiologists physical status; sex; duration of anaesthesia; postoperative delirium; PTSS-14 score 7 days after surgery; postoperative vomiting and nausea; postoperative pain; and preoperative depression.

Statistics: Univariate statistical analysis was performed with Fisher's exact test and Spearman correlation. A backward logistic regression was performed.

Results: A total of 559 out of 1277 patients were included. Sixty-six patients (12%) were identified with PTSD 3 months after surgery. Seventy-seven patients (14%) were identified with postoperative delirium. Independent associated factors in the backward logistic regression were postoperative delirium (risk factor) and preoperative depression (protective factor).

Conclusion: The prevalence of PTSD 3 months after surgery in elderly patients was high using the screening instrument PTSS-14. Postoperative delirium is a risk factor for PTSD 3 months after surgery.

Trial registration: ISRCTN Register: 36437985. http://www.controlled-trials.com/ISRCTN36437985/