Effects of the Million Hearts Model on Myocardial Infarctions, Strokes, and Medicare Spending: A Randomized Clinical Trial

Abstract

Importance: The Million Hearts Model paid health care organizations to assess and reduce cardiovascular disease (CVD) risk. Model effects on long-term outcomes are unknown.

Objective: To estimate model effects on first-time myocardial infarctions (MIs) and strokes and Medicare spending over a period up to 5 years.

Design, setting, and participants: This pragmatic cluster-randomized trial ran from 2017 to 2021, with organizations assigned to a model intervention group or standard care control group. Randomized organizations included 516 US-based primary care and specialty practices, health centers, and hospital-based outpatient clinics participating voluntarily. Of these organizations, 342 entered patients into the study population, which included Medicare fee-for-service beneficiaries aged 40 to 79 years with no previous MI or stroke and with high or medium CVD risk (a 10-year predicted probability of MI or stroke [ie, CVD risk score] ≥15%) in 2017-2018.

Intervention: Organizations agreed to perform guideline-concordant care, including routine CVD risk assessment and cardiovascular care management for high-risk patients. The Centers for Medicare & Medicaid Services paid organizations to calculate CVD risk scores for Medicare fee-for-service beneficiaries. CMS further rewarded organizations for reducing risk among high-risk beneficiaries (CVD risk score ≥30%).

Main outcomes and measures: Outcomes included first-time CVD events (MIs, strokes, and transient ischemic attacks) identified in Medicare claims, combined first-time CVD events from claims and CVD deaths (coronary heart disease or cerebrovascular disease deaths) identified using the National Death Index, and Medicare Parts A and B spending for CVD events and overall. Outcomes were measured through 2021.

Results: High- and medium-risk model intervention beneficiaries (n = 130 578) and standard care control beneficiaries (n = 88 286) were similar in age (median age, 72-73 y), sex (58%-59% men), race (7%-8% Black), and baseline CVD risk score (median, 24%). The probability of a first-time CVD event within 5 years was 0.3 percentage points lower for intervention beneficiaries than control beneficiaries (3.3% relative effect; adjusted hazard ratio [HR], 0.97 [90% CI, 0.93-1.00]; P = .09). The 5-year probability of combined first-time CVD events and CVD deaths was 0.4 percentage points lower in the intervention group (4.2% relative effect; HR, 0.96 [90% CI, 0.93-0.99]; P = .02). Medicare spending for CVD events was similar between the groups (effect estimate, -$1.83 per beneficiary per month [90% CI, -$3.97 to -$0.30]; P = .16), as was overall Medicare spending including model payments (effect estimate, $2.11 per beneficiary per month [90% CI, -$16.66 to $20.89]; P = .85).

Conclusions and relevance: The Million Hearts Model, which encouraged and paid for CVD risk assessment and reduction, reduced first-time MIs and strokes. Results support guidelines to use risk scores for CVD primary prevention.

Trial registration: ClinicalTrials.gov Identifier: NCT04047147.

Figure 1.. Flow of Organizations and Beneficiaries From Random Assignment Through Analysis

^aThe Centers for Medicare and Medicaid Services (CMS) issued a broad request for applications to participate in the Million Hearts Model. To participate, organizations had to submit a complete application, have at least 1 practitioner enrolled in and eligible to bill for Medicare Part B, use an electronic health record system certified by the Office of the National Coordinator for Health Information Technology, and have met the criteria for the CMS electronic health record Incentive Programs, also known as Meaningful Use, in performance year 2014. Five organizations were ineligible because they failed to meet 1 or more of these criteria. CMS rejected an additional 6 organizations for ambiguous or unsatisfactory responses to application questions about these same criteria or about willingness or ability to participate in the model. ^bAssignment occurred at the organization level. CMS used a minimization procedure (adaptive randomization), equivalent to random assignment (eMethods 1 in Supplement 2). ^cIn the control group, the number of participating practitioners per organization was capped at 20. This resulted in fewer beneficiaries per organization, on average, in the control group vs the intervention group. ^dOrganizations were implicitly excluded from the analysis population if none of their model beneficiaries met the inclusion criteria. ^eBeneficiaries had to be aged 40 to 79 years when entering the model with no prior acute myocardial infarction, prior stroke, kidney failure, or hospice use. ^fAll beneficiaries remained alive and in Medicare fee-for-service at least 1 day after entering the model, although censoring sometimes occurred later due to beneficiaries dying or exiting Medicare fee-for-service.

Figure 2.. Cumulative Probability^a of First-Time Cardiovascular Disease (CVD) Event (Regression-Adjusted Mean Cumulative Probability Functions)

^aThe cumulative probabilities are modeled based on Cox proportional-hazards regressions of intervention and control group beneficiaries. The intervention group line represents the percentage of intervention group beneficiaries estimated to experience an event during the model. The control group line represents the percentage of beneficiaries who would experience an event over the same period, if those beneficiaries had the same characteristics (covariates) as intervention group beneficiaries but did not experience the Million Hearts Model.