Abstract
BACKGROUND/OBJECTIVE: Regular physical activity (PA) has been associated with improved cognitive function, but its effect on postoperative delirium (POD) has not been established. Our objectives were to determine the effect of baseline PA on the incidence of POD in older patients undergoing elective orthopedic surgery and to determine whether these effects were independent of cognitive reserve. We hypothesize that PA protects against POD by bolstering physiologic reserve needed to withstand the stressors of surgery. DESIGN: Secondary analysis of a prospective, single-center, cohort study. SETTING: Urban academic hospital. PARTICIPANTS: A total of 132 nondemented, English-speaking adults older than 60 years undergoing elective orthopedic surgery. MEASUREMENTS: Subjects were screened for POD and delirium severity using the Confusion Assessment Method and the Memorial Delirium Assessment Scale. Baseline cognitive activities and PAs were assessed with a validated Leisure Activity Scale. Regular PA was categorized as 6 to 7 days per week. The association of regular PA with incidence of POD was assessed using multivariable logistic regression, adjusting for age, sex, Charlson Comorbidity Index, cognitive reserve, and cognitive function. Linear regression was used to assess the association of delirium severity with regular PA. RESULTS: Of 132 patients, 41 (31.1%) developed POD. Regular PA was associated with a 74% lower odds of developing POD (odds ratio [OR] = 0.26; 95% confidence interval [CI] = 0.08-0.82). There was no significant interaction between PA and cognitive reserve (P = .70). Of 85 women, 25 (29.4%), and of 47 men, 16 (34.0%) developed POD. In stratified analysis, women who engaged in regular PA had dramatically lower odds of POD (OR = 0.08; 95% CI = 0.01-0.63) compared with men (OR = 0.93; 95% CI = 0.18-4.97). CONCLUSIONS: Regular PA is associated with decreased incidence of POD, especially among women. Future studies should address the basis of sex differences in PA benefits on delirium. J Am Geriatr Soc 67:2260-2266, 2019.