Using a Social Determinants of Health Summary Measure to Predict General Health Status in the BRFSS

Purpose

The social determinants of health (SDoH) refer to a broad array of social and contextual experiences that influence health, including but not limited to education, healthcare, economic stability, social and community context, and the built environment. ¹ Others have included factors such as racial/ethnic discrimination, occupational exposures, social support, and stress as among the many exposures or characteristics that can be considered SDoH. ² These experiences are highly inter-related and inter-dependent, and there is ample evidence that the profound influence that the SDoH have on health is not due to one experience vs another but rather the overall burden of risk conferred by SDoH. ³ In addition, researchers have begun to consider new approaches to modeling COVID-19 to better include information on SDoH ⁴ and assess the role that SDoH plays in vulnerability vs resilience following a disaster. ⁵

The Behavioral Risk Factor Surveillance System (BRFSS) is a national system of health-related telephone surveys, funded by the Centers for Disease Control and Prevention (CDC). These surveys collect statewide data on health-related behaviors, chronic diseases, and utilization of preventive services. ⁶ While there is a core set of required questions, CDC has offered “optional modules”—standardized sets of questions on special topics. One such optional module collects information on food insecurity, housing insecurity, financial instability, and stress. This module has evolved over time with the first set of questions introduced in 1996. While the specific questions have changed over time and will continue to change as our knowledge about SDoH increases, the goal—to assess the social, occupational, and financial conditions experienced by individual respondents—has remained the same. ⁶

Given the importance of the SDoH, combined with the multitude of measures, there is a need to succinctly describe the overall burden of risk due to SDoH. The objective of this study was to create a single measure that summarizes overall SDoH burden (of a subset of SDoH) and assess the relationship between the SDoH measure and overall health.

Methods

Measures

The outcome measures included self-rated general health, days of poor physical health, and days of poor mental health. General health was assessed by asking: “Would you say that in general your health is … excellent, very good, good, fair, or poor?” Responses were collapsed into 2 categories: “excellent/very good/good” vs “fair/poor.” Physical health was assessed by asking: “Thinking about your physical health, which includes physical illness and injury, for how many days during the past 30 days was your physical health not good?” Responses were collapsed into 2 categories: “0-14 days/month” vs “15+ days/month.” Mental health was assessed by asking “Thinking about your mental health, which includes stress, depression, and problems with emotions, for how many days during the past 30 days was your mental health not good?” Responses were collapsed: “0-14 days/month” vs “15+ days/month.”

The MA BRFSS included 6 of the 7 items in the CDC-created SDoH module. The response categories were dichotomized (0 = minimal/no experience vs 1 = experience of the SDoH risk factor). The following items were included: (1) housing instability (2 items): “During the last 12 months, was there a time when you were not able to pay your mortgage, rent or utility bills?” (no/yes) and “In the last 12 months, how many times have you moved from one home to another?” (0–1/2+ moves); (2) perceptions of neighborhood crime: “How safe from crime do you consider your neighborhood to be?” (safe/unsafe); (3) food insecurity (2 items): “The food that I bought just didn't last, and I didn't have money to get more” (never vs often/sometimes) and “I couldn't afford to eat balanced meals” (never vs often/sometimes); (4) financial instability: “In general, how do your finances usually work out at the end of the month?” (money left over or just enough vs not enough). Demographic covariates included age, education, annual income, gender, and race/ethnicity. Due to a large number of missing responses, annual income included a “missing” category (see Table 1).

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Table 1.

Massachusetts BRFSS 2017–2019. Sample Characteristics and Global Health Outcome Measures. N = 16,929.

	Weighted % (95% CI)
Demographic characteristic Age 18–24	12.1% (11.3–12.9)
25–34	15.2% (14.4–16.0)
35–44	15.5% (14.7–16.3)
45–54	16.4% (15.6–17.1)
55–64	18.4% (17.7–19.2)
65–74	13.3% (12.7–13.9)
75+	9.2% (8.6–9.7)
Education Less than high school	10.0% (9.2–10.8)
High school	25.5% (24.5–26.4)
College 1–3 years	26.9% (25.9–27.8)
College graduate or more	37.7% (35.8–38.7)
Annual income ≤ $25k	13.3% (12.6–14.1)
$25k–$34,999	6.1% (5.6–6.6)
$35k–$49,999	8.8% (8.2–9.4)
$50k–$74,999	11.2% (10.5–11.8)
$75k+	39.6% (38.5–40.6)
Missing	21.0% (20.1–21.9)
Gender Female	52.8% (51.7–53.8)
Race/Ethnicity White, non-Hispanic	74.8% (73.9–75.8)
Black, non-Hispanic	6.7% (6.2–7.3)
Hispanic	10.5% (9.8–11.1)
Asian	6.7% (6.0–7.4)
Other	1.2% (1.0–1.4)

Results

Fourteen percent of respondents rated their health as fair or poor, 10% reported 15+ days of poor physical health in the last month, and 12% reported 15+ days of poor mental health in the past month (see Table 1 for demographic characteristics).

The prevalence of any single SDoH was low. The number of respondents reporting aspects of housing instability ranged from 8% (unable to pay mortgage, rent, utility bills) to 3% (2+ moves in past year), 4% of respondents reported that their neighborhood was unsafe or extremely unsafe, 14% reported that they often or sometimes could not afford balanced meals, 12% ran out of food often or sometimes, and 9% ran out of money at the end of each month. The number of respondents who refused any single item was highest in the question about finances (4%). The other questions were refused by less than 1% of respondents.

The SDoH summary measure revealed that most respondents (75%) did not experience any of the SDoH risks, while 11% reported one, 6% reported two, 4% reported three, and 4% reported four or more. An increase in the burden of SDoH risk experiences was associated with an increase in the likelihood of fair or poor health, after controlling for demographic confounders. In adjusted analyses, those who reported experiencing 1, 2, 3, or 4+ SDoH had 1.6-, 2.9-, 3.2-, or 5.3-fold odds (respectively) of fair or poor health, compared to those who reported zero SDoH. Respondents who reported experiencing 1, 2, 3, or 4+ SDoH had 1.6-, 2.2-, 3.3-, or 4.7-fold odds (respectively) of 15+ days/month of poor physical health. Finally, respondents who reported experiencing 1, 2, 3, or 4+ SDoH had 1.7-, 2.4-, 4.8-, or 6.5-fold odds (respectively) of reporting poor mental health days (Table 2).

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Table 2.

Massachusetts BRFSS 2017–2019. Multivariate Logistic Regression—Social Determinants of Health Summary Measure to Predict General Health, Physical Health, and Mental Health. Unadjusted and Adjusted Results. N = 16,929.

	Unadjusted OR (95% CI)	Adjusted OR* (95% CI)
General health-rated as fair or poor
0 SDoH (ref)	1	1
1 SDoH	1.9 (1.6–2.4)	1.6 (1.3–2.0)
2 SDoH	3.9 (3.2–4.8)	2.9 (2.3–3.7)
3 SDoH	5.0 (4.0–6.4)	3.2 (2.4–4.3)
4+ SDoH	7.6 (6.0–9.7)	5.3 (4.0–7.0)
15+ days/Month of poor physical health
0 SDoH (ref)	1	1
1 SDoH	1.6 (1.3–2.0)	1.6 (1.2–2.0)
2 SDoH	2.6 (2.0–3.3)	2.2 (1.7–3.0)
3 SDoH	4.1 (3.1–5.3)	3.3 (2.4–4.5)
4+ SDoH	5.9 (4.6–7.6)	4.7 (3.5–6.4)
15+ days/Month of poor mental health
0 SDoH (ref)	1	1
1 SDoH	2.1 (1.7–2.6)	1.7 (1.4–2.2)
2 SDoH	3.3 (2.6–4.2)	2.4 (1.8–3.2)
3 SDoH	6.2 (4.9–8.0)	4.8 (3.6–6.3)
4+ SDoH	9.0 (7.0–11.6)	6.5 (4.9-8.6)

Discussion

Limitations

An important limitation of this study is the cross-sectional design, as it is difficult to determine the potential direction of causation. Missing data may also be an important source of bias, as the average income may be lower or higher or the total burden of SDoH may be higher.

The SDoH summary measure is not an exhaustive measure and does not include important aspects of the SDoH such as healthcare access, working conditions, or social networks—to name but a few. Additionally, the summary measure provides more information about some SDoH aspects (food and housing insecurity) than others (financial instability and neighborhood safety). Rather, this study is intended to provide a first look at succinctly summarizing the effect of social factors on health, and demonstrating, in addition to their individual effects, there may also be an important combined effect.

Significance

Important strengths of this study include the large, representative sample and the use of BRFSS, which uses validated questions and has a high response rate. As the body of work investigating the health impact of adverse childhood experiences has so elegantly demonstrated, it is not simply one risk experience vs another that matters for health, but rather the overall burden of experience. ¹¹ Similarly, the findings of this study indicate that the overall burden of SDoH, such as financial instability, housing instability, perceptions of neighborhood crime and food insecurity, is an important predictor of health, over and above the contribution of demographic characteristics. Current and planned research to investigate opportunities to include SDoH in COVID-19 models has outlined the problems in including SDoH measures.^4,5 The approach to quantifying SDoH burden utilized in this study may be helpful in modeling approaches, as it quantifies the vulnerability conferred by SDoH experiences.

“SO WHAT?”

What is already known on this topic?

Social determinants of health have a profound influence on health and health-related behaviors.

What does this article add?

There is evidence that the SDoH are inter-dependent and may work together to affect health. This article demonstrates how a summary of SDoH “exposure” relates to general health outcomes and provides evidence that SDoH “exposure burden” is an important facet of SDoH.

What are the implications for health promotion practice or research?

This study demonstrates that a succinct SDoH summary measure from the BRFSS is associated with general health measures in a strong and graded fashion.