How Does Intraoperative Sedation Affect Postoperative Delirium Risk?


Limiting levels of intraoperative sedation during hip fracture repair had no benefit for the reduction of incident delirium in severely ill older adults, according to the results of a recent study.


Postoperative delirium (PD) is a common complication following major surgery in older adults. Previous research has suggested that sedative and analgesic medications are iatrogenic risk factors for delirium in postsurgical patients, however, few studies have examined intraoperative sedation as a modifiable risk factor for delirium.



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The researchers conducted a double-blind randomized clinical trial (A Strategy to Reduce the Incidence of Postoperative Delirium in Elderly Patients [STRIDE]) from November 18, 2011 to May 19, 2016. The trial included 225 eligible patients undergoing elective hip fracture repair with spinal anesthesia and propofol sedation. Two-hundred participated in the study.


The 200 participants were randomized to either 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. The average Charlson Comorbidity Index (CCI) score was 1.8.


Overall, 39% of patients in the deep sedation group and 34% of those in the light sedation group experienced postoperative delirium 1 to 5 days after surgery. Intention-to-treat analyses indicated no statistically significant difference between groups in the risk of incident delirium, however, in a prespecified subgroup analysis, sedation levels did effect delirium risk when stratified by CCI. In low comorbid states (CCI = 0), heavier vs lighter sedation levels doubled the risk of delirium (hazard ratio 2.3), but level of sedation did not affect delirium risk in patients with a CCI or more than 0.


“The STRIDE trial suggests that the selection of sedation levels can be an important means of decreasing PD in many patients. However, the associated benefits of lighter sedation levels may be obscured by competing baseline comorbidities, placing patients at risk of developing PD. Given the STRIDE trial findings, the challenge for future research will be to determine the mechanisms and interactional relationships between comorbidities and precipitating risk factors for PD.”


—Michael Potts



Sieber FE, Neufeld KJ, Gottschalk A, et al. Effect of depth of sedation in older patients undergoing hip fracture repair on postoperative delirium [published online August 8, 2018]. JAMA Surg. doi:10.1001/jamasurg.2018.2602