Cardiovascular Risk Associated With Social Determinants of Health at Individual and Area Levels

Abstract

Importance: The benefit of adding social determinants of health (SDOH) when estimating atherosclerotic cardiovascular disease (ASCVD) risk is unclear.

Objective: To examine the association of SDOH at both individual and area levels with ASCVD risks, and to assess if adding individual- and area-level SDOH to the pooled cohort equations (PCEs) or the Predicting Risk of CVD Events (PREVENT) equations improves the accuracy of risk estimates.

Design, setting, and participants: This cohort study included participants data from 4 large US cohort studies. Eligible participants were aged 40 to 79 years without a history of ASCVD. Baseline data were collected from 1995 to 2007; median (IQR) follow-up was 13.0 (9.3-15.0) years. Data were analyzed from September 2023 to February 2024.

Exposures: Individual- and area-level education, income, and employment status.

Main outcomes and measures: ASCVD was defined as the composite outcome of nonfatal myocardial infarction, death from coronary heart disease, and fatal or nonfatal stroke.

Results: A total of 26 316 participants were included (mean [SD] age, 61.0 [9.1] years; 15 494 women [58.9%]; 11 365 Black [43.2%], 703 Chinese American [2.7%], 1278 Hispanic [4.9%], and 12 970 White [49.3%]); 11 764 individuals (44.7%) had at least 1 adverse individual-level SDOH and 10 908 (41.5%) had at least 1 adverse area-level SDOH. A total of 2673 ASCVD events occurred during follow-up. SDOH were associated with increased risk of ASCVD at both the individual and area levels, including for low education (individual: hazard ratio [HR], 1.39 [95% CI, 1.25-1.55]; area: HR, 1.31 [95% CI, 1.20-1.42]), low income (individual: 1.35 [95% CI, 1.25-1.47]; area: HR, 1.28 [95% CI, 1.17-1.40]), and unemployment (individual: HR, 1.61 [95% CI, 1.24-2.10]; area: HR, 1.25 [95% CI, 1.14-1.37]). Adding area-level SDOH alone to the PCEs did not change model discrimination but modestly improved calibration. Furthermore, adding both individual- and area-level SDOH to the PCEs led to a modest improvement in both discrimination and calibration in non-Hispanic Black individuals (change in C index, 0.0051 [95% CI, 0.0011 to 0.0126]; change in scaled integrated Brier score [IBS], 0.396% [95% CI, 0.221% to 0.802%]), and improvement in calibration in White individuals (change in scaled IBS, 0.274% [95% CI, 0.095% to 0.665%]). Adding individual-level SDOH to the PREVENT plus area-level social deprivation index (SDI) equations did not improve discrimination but modestly improved calibration in White participants (change in scaled IBS, 0.182% [95% CI, 0.040% to 0.496%]), Black participants (0.187% [95% CI, 0.039% to 0.501%]), and women (0.289% [95% CI, 0.115% to 0.574%]).

Conclusions and relevance: In this cohort study, both individual- and area-level SDOH were associated with ASCVD risk; adding both individual- and area-level SDOH to the PCEs modestly improved discrimination and calibration for estimating ASCVD risk for Black individuals, and adding individual-level SDOH to PREVENT plus SDI also modestly improved calibration. These findings suggest that both individual- and area-level SDOH may be considered in future development of ASCVD risk assessment tools, particularly among Black individuals.

Figure 1.. Associations of Individual-Level and Area-Level Social Determinants of Health (SDOH) With Atherosclerotic Cardiovascular Disease (ASCVD)

The associations between SDOH and ASCVD were assessed using Cox proportional hazards models. All models were stratified by study cohort, allowing the baseline hazard function to vary across different cohorts. ^aModel 1 was adjusted for sex and age at the baseline visit. ^bModel 2 included adjustments in model 1 and was further adjusted for race and ethnicity. ^cModel 3 included adjustments of the other models and was further adjusted for traditional ASCVD risk factors included in the pooled cohort equations (including smoking status, total cholesterol, high-density lipoprotein cholesterol, systolic blood pressure, use of antihypertension medication, and diabetes status) and use of lipid-lowering medication.

Figure 2.. Changes in Harrell C Index and Scaled Integrated Brier Score (IBS) When Adding Individual-Level and Area-Level Social Determinants of Health (SDOH) to the Pooled Cohort Equations

The 95% CI of change in C index and change in scaled IBS were calculated by nonparametric bootstrapping.

Figure 3.. Calibration Plots of Pooled Cohort Equations (PCEs) and PCEs Plus Social Determinants of Health (SDOH) at Both Individual- and Area-Level by Race and Ethnicity and by Sex

Calibration plots compared estimated with observed 10-year atherosclerotic cardiovascular disease (ASCVD) risk by decile of the estimated risk. Orange lines represent calibration curves for models with only the PCEs; blue lines, calibration curves for models with PCEs plus individual- and area-level SDOH.