What is it?
Sutter Health created the HEI to quantify avoidable emergency department utilization for ambulatory care sensitive conditions (ACSCs) compared to what would be expected if health equity was realized. The goal of this metric is to present an analytical method for stand-alone facilities or health systems to identify disparities and prioritize initiatives to reduce health inequality in specific patient populations. The HEI identifies inequities that are addressable by the health care system, recognizing that external factors contribute to underlying disparities within the community.
To calculate the HEI, Sutter Health examined the ratio of observed to expected encounters. This ratio is called the health equity score (HES), as seen in Figure 1. The HES is calculated using many inputs such as the population distribution in the catchment area, state-level condition prevalence, the average tendency to utilize a specific facility, and the frequency of that utilization.
To calculate the HES, Sutter Health divided their patient population into 24 possible subgroups based on age, sex, and race/ethnicity.
The HEI displays the magnitude of disparities across all 24 possible permutations of age, sex and race/ethnicity. It measures the frequency of hospital encounters by those factors and determines the areas where the amount by which each HES is above one – that is, higher than expected.
- If the HEI is >1: This means that the number of observed encounters exceeds the number of expected encounters. This indicates that there may be inequity in the treatment of that condition and may represent an opportunity for intervention.
- If the HEI is equal to 1: This assumes that there is equity from the health system perspective since the number of observed encounters matches the expected encounters.
- If the HEI is <1: This means that the number of observed encounters is less than expected given underlying disparities in the community. This can occur for a variety of reasons, one being that a segment of the patient population is using the outpatient setting to treat their condition more than expected.
Why is it useful?
The health equity index is a way to uncover disparities in granular populations, and it allows organizations to analyze their data through an intersectional lens. Layering multiple demographics in their analysis at once allows organizations to better understand how different types of oppression and privilege interact to impact outcomes. Since the index identifies granular populations, health systems can allocate resources for interventions that seek to address disparities for specific groups. Additionally, health systems can leverage the index to assess the effectiveness of their interventions.
The index provides an internal equity standard for health systems to calculate which groups are experiencing disparities in their care. The HEI quantifies inequity in a health system while accounting for the demographic variation in their existing catchment area, which is often beyond the control of the health system to alter unilaterally. Since the index uses an internal standard as the baseline against which each of the 24 possible subgroups can be compared, it can normalize it’s predictions to the system’s local demographics. To date, health systems typically stratify their outcomes and process-of-care data against the dominant group in their population (typically white males) for whom best-case-scenario outcomes are assumed. However, this approach relies on the assumption that the dominant group actually experiences the best outcomes, which is not always the case.