Effect of Depth of Sedation in Older Patients Undergoing Hip Fracture Repair on Postoperative Delirium
Authors: Frederick E. Sieber, Karin J. Neufeld, Allan Gottschalk, George E. Bigelow, Esther S. Oh, Paul B. Rosenberg, Simon C. Mears, Kerry J. Stewart, Jean-Pierre P. Ouanes, Mahmood Jaberi, Erik A. Hasenboehler, Tianjing Li, Nae-Yuh Wang
Journal: JAMA Surgery (2018)

<h3>Importance</h3> Postoperative delirium is the most common complication following major surgery in older patients. Intraoperative sedation levels are a possible modifiable risk factor for postoperative delirium. <h3>Objective</h3> To determine whether limiting sedation levels during spinal anesthesia reduces incident delirium overall. <h3>Design, Setting, and Participants</h3> This double-blind randomized clinical trial (A Strategy to Reduce the Incidence of Postoperative Delirum in Elderly Patients [STRIDE]) was conducted from November 18, 2011, to May 19, 2016, at a single academic medical center and included a consecutive sample of older patients (≥65 years) who were undergoing nonelective hip fracture repair with spinal anesthesia and propofol sedation. Patients were excluded for preoperative delirium or severe dementia. Of 538 hip fractures screened, 225 patients (41.8%) were eligible, 10 (1.9%) declined participation, 15 (2.8%) became ineligible between the time of consent and surgery, and 200 (37.2%) were randomized. The follow-up included postoperative days 1 to 5 or until hospital discharge. <h3>Interventions</h3> Heavier (modified observer's assessment of sedation score of 0-2) or lighter (observer's assessment of sedation score of 3-5) propofol sedation levels intraoperatively. <h3>Main Outcomes and Measures</h3> Delirium on postoperative days 1 to 5 or until hospital discharge determined via consensus panel using<i>Diagnostic and Statistical Manual of Mental Disorders </i>(Fourth Edition, Text Revision) criteria. The incidence of delirium was compared between intervention groups with and without stratification by the Charlson comorbidity index (CCI). <h3>Results</h3> Of 200 participants, the mean (SD) age was 82 (8) years, 146 (73%) were women, 194 (97%) were white, and the mean (SD) CCI was 1.5 (1.8). One hundred participants each were randomized to receive lighter sedation levels or heavier sedation levels. A good separation of intraoperative sedation levels was confirmed by multiple indices. The overall incident delirium risk was 36.5% (n = 73) and 39% (n = 39) vs 34% (n = 34) in heavier and lighter sedation groups, respectively (<i>P</i> = .46). Intention-to-treat analyses indicated no statistically significant difference between groups in the risk of incident delirium (log-rank test χ<sup>2</sup>, 0.46;<i>P</i> = .46). However, in a prespecified subgroup analysis, when stratified by CCI, sedation levels did effect the delirium risk (<i>P</i>for interaction = .04); in low comorbid states (CCI = 0), heavier vs lighter sedation levels doubled the risk of delirium (hazard ratio, 2.3; 95% CI, 1.1- 4.9). The level of sedation did not affect delirium risk with a CCI of more than 0. <h3>Conclusions and Relevance</h3> In the primary analysis, limiting the level of sedation provided no significant benefit in reducing incident delirium. However, in a prespecified subgroup analysis, lighter sedation levels benefitted reducing postoperative delirium for persons with a CCI of 0. <h3>Trial Registration</h3> clinicaltrials.gov Identifier:NCT00590707