Measuring Equity in Readmission as a Distinct Assessment of Hospital Performance

Abstract

Importance: Equity is an essential domain of health care quality. The Centers for Medicare & Medicaid Services (CMS) developed 2 Disparity Methods that together assess equity in clinical outcomes.

Objectives: To define a measure of equitable readmissions; identify hospitals with equitable readmissions by insurance (dual eligible vs non-dual eligible) or patient race (Black vs White); and compare hospitals with and without equitable readmissions by hospital characteristics and performance on accountability measures (quality, cost, and value).

Design, setting, and participants: Cross-sectional study of US hospitals eligible for the CMS Hospital-Wide Readmission measure using Medicare data from July 2018 through June 2019.

Main outcomes and measures: We created a definition of equitable readmissions using CMS Disparity Methods, which evaluate hospitals on 2 methods: outcomes for populations at risk for disparities (across-hospital method); and disparities in care within hospitals' patient populations (within-a-single-hospital method).

Exposures: Hospital patient demographics; hospital characteristics; and 3 measures of hospital performance-quality, cost, and value (quality relative to cost).

Results: Of 4638 hospitals, 74% served a sufficient number of dual-eligible patients, and 42% served a sufficient number of Black patients to apply CMS Disparity Methods by insurance and race. Of eligible hospitals, 17% had equitable readmission rates by insurance and 30% by race. Hospitals with equitable readmissions by insurance or race cared for a lower percentage of Black patients (insurance, 1.9% [IQR, 0.2%-8.8%] vs 3.3% [IQR, 0.7%-10.8%], P < .01; race, 7.6% [IQR, 3.2%-16.6%] vs 9.3% [IQR, 4.0%-19.0%], P = .01), and differed from nonequitable hospitals in multiple domains (teaching status, geography, size; P < .01). In examining equity by insurance, hospitals with low costs were more likely to have equitable readmissions (odds ratio, 1.57 [95% CI, 1.38-1.77), and there was no relationship between quality and value, and equity. In examining equity by race, hospitals with high overall quality were more likely to have equitable readmissions (odds ratio, 1.14 [95% CI, 1.03-1.26]), and there was no relationship between cost and value, and equity.

Conclusion and relevance: A minority of hospitals achieved equitable readmissions. Notably, hospitals with equitable readmissions were characteristically different from those without. For example, hospitals with equitable readmissions served fewer Black patients, reinforcing the role of structural racism in hospital-level inequities. Implementation of an equitable readmission measure must consider unequal distribution of at-risk patients among hospitals.

Figure 1.. Cohort Development in a Study of Equity in the Hospital-Wide Readmission Measure

^aThere are 2 Disparity Methods: (1) the across-hospital method, which compares a hospital’s risk-standardized readmission rates (RSRR) for dual-eligible or Black patients to the median RSRR for dual-eligible or Black patients across all hospitals; and (2) the within-a-single-hospital method, which measures the absolute adjusted readmission rate difference between dual-eligible vs non–dual-eligible patients or Black vs White patients within an individual hospital’s patient population. Hospitals achieved equitable readmissions if they met threshold scores for both Disparity Methods. ^bHospitals were eligible for equity assessment if they met eligibility criteria for each of the Disparity Methods. Reasons for exclusion will not sum because some hospitals were excluded for more than 1 reason and are accounted in more than 1 criterion standard. ^cEligibility criterion 1, the across-hospital method: cared for at least 25 patients in the group at risk for inequities. ^dEligibility criteria 2A, the within-a-single-hospital method: cared for at least 12 patients within each group at risk and not at risk for disparities and at least 25 patients between both groups. ^eEligibility criterion 2B, the within-a-single-hospital method: the hospitals’ predicted readmission rate for dual-eligible or Black patients was not better than that of non–dual-eligible or White patients by more than 1%. ^fHospitals achieved equitable readmissions if they met threshold scores for both Disparity Methods. Subcategories will not sum because some hospitals did not meet either threshold score. ^gThe across-hospital method threshold score: a hospital’s RSRR for the at-risk group was better (lower) than the median RSRR for that group across all hospitals (ie, the hospital was in the top half of performers). ^hThe within-a-single-hospital method threshold score: the absolute adjusted readmission rate difference between the group at risk and not at risk of inequities was between −1% and 1%.

Figure 2.. State-Level Percentages of Hospitals Eligible for Examination of Disparities and With Equitable Readmissions

A and C, Color shading represents the percentage of total hospitals in each state eligible for examination of disparities by insurance (3414 of 4638 [73.6%]) and race (1962 of 4638 [42.3%]). The numbers listed in each state represent the the total number of hospitals in each state included in the Centers for Medicare & Medicaid Services Hospital-Wide Readmission measure cohort; see Figure 1). Eligibility/inclusion criteria: for the across-hospitals method, cared for at least 25 patients in the at-risk group; for the within-a-single-hospital method, cared for at least 12 patients in the at-risk group and 25 patients total. B and D, Color shading represents the percentage of hospitals in each state with equitable readmissions by insurance (592 of 3414 [17.3%]) and race (596 of 1962 [30.4%]). The numbers listed in each state represent the the total number of hospitals eligible for the Disparity Methods.

Figure 3.. Distribution of Performance of Eligible Hospitals on Disparity Methods

This figure illustrates eligible hospitals’ performance on Disparity Methods and how the across-hospitals and within-a-single-hospital methods were used to identify hospitals with equitable readmissions. The vertical axis depicts hospitals’ performance on criterion 1, the across-hospitals method. Hospitals met the threshold score for this criterion if their risk-standardized readmission rate (RSRR) for the at-risk group was better (lower) than the median RSRR for that group across all hospitals (ie, they were in the top half of performers). We classified those hospitals in the top half of performers as having low readmission rates and those in the bottom half of performers as having high readmission rates. The horizontal axis depicts hospitals’ performance on criterion 2, the within-a-single-hospital method. Hospitals met this criterion if, among their patient population, the absolute adjusted readmission rate difference (ARD) between the group at risk and not at risk of inequities was between −1% and 1%. We classified those hospitals with an ARD between −1% and 1% as having a narrow gap and those with an ARD greater than 1% as having a large gap.

Figure 4.. Comparing Characteristics of Hospitals With and Without Equitable Readmissions by Insurance and Race: Differences in Observed Proportions

Differences were calculated by subtracting the proportion for hospitals without equitable readmissions from the proportion with equitable readmissions. Raw proportions are also reported. See the Table for definitions of each characteristic.

Figure 5.. Relationships Between Equitable Readmissions by Insurance and Race, Measures of High Performance, and Domain Scores of Hospital Quality

^aThese analyses examined the unadjusted odds that hospitals with high quality (4 or 5 overall hospital star rating on Hospital Care Compare), low cost (Medicare spending per beneficiary score in the lowest quintile of all hospitals), and high value (achieved both high quality and low cost) also had equitable readmissions. ^bDetermined by the availability of star ratings and Medicare spending per beneficiary data for each hospital. Hospitals without assigned star ratings were excluded from analysis of high quality and high value. ^cThe star ratings are constructed from underlying continuous scores. The separate scores for each domain are averaged to create the single overall score. The underlying continuous scores are standardized (mean, 0; SD, 1), which gives them a natural interpretation (eg, for every change of 1 standard deviation on the continuous readmission score, there is a 1.29 times increased odds that a hospital will be classified as having equitable readmissions by race).