Neighborhood-Level Social Disadvantage and Risk of Delirium Following Major Surgery

Abstract

Background/objectives: Delirium is a common postoperative complication associated with prolonged length of stay, hospital readmission, and premature mortality. We explored the association between neighborhood-level characteristics and delirium incidence and severity, and compared neighborhood- with individual-level indicators of socioeconomic status in predicting delirium incidence.

Design: A prospective observational cohort of patients enrolled between June 18, 2010, and August 8, 2013. Baseline interviews were conducted before surgery, and delirium/delirium severity was evaluated daily during hospitalization. Research staff evaluating delirium were blinded to baseline cognitive status.

Setting: Two academic medical centers in Boston, MA.

Participants: A total of 560 older adults, aged 70 years or older, undergoing major noncardiac surgery.

Intervention: The Area Deprivation Index (ADI) was used to characterize each neighborhood's socioeconomic disadvantage.

Measurements: Delirium was assessed using the Confusion Assessment Method (CAM) long form. Delirium severity was calculated using the highest value of CAM Severity score (CAM-S) occurring during daily hospital assessments (CAM-S Peak).

Results: Residing in the most disadvantaged neighborhoods (ADI > 44) was associated with a higher risk of incident delirium (12/26; 46%), compared with the least disadvantaged neighborhoods (122/534; 23%) (risk ratio (RR) (95% confidence interval (CI)) = 2.0 (1.3-3.1). The CAM-S Peak score was significantly associated with ADI (Spearman rank correlation, ρ = 0.11; P = .009). Mean CAM-S Peak scores generally rose from 3.7 to 5.3 across levels of increasing neighborhood disadvantage. The RR (95% CI) values associated with individual-level markers of socioeconomic status and cultural background were: 1.2 (0.9-1.7) for education of 12 years or less; 1.3 (0.8-2.1) for non-White race; and 1.7 (1.1-2.6) for annual household income of less than $20,000. None of these individual-level markers exceeded the ADI in terms of effect size or significance for prediction of delirium risk.

Conclusions: Neighborhood-level makers of social disadvantage are associated with delirium incidence and severity, and demonstrated an exposure-response relationship. Future studies should consider contextual-level metrics, such as the ADI, as risk markers of social disadvantage that can help to guide delirium treatment and prevention.

Keywords: Area Deprivation Index; clinical outcomes in hospitalization; delirium; delirium severity; social determinants of health.

Figure 1.

Association between ADI and CAM-S Peak in the SAGES Cohort (N=560) Abbreviations: ADI, Area deprivation index; CAM-S, The Confusion Assessment Method Severity Score; CAM-S Peak, The highest single CAM-S rating during hospitalization. ^aAnalyses were completed using linear regression lines and 95% confidence intervals were calculated using a standard formula (mean ±1.96 * SE).