Stress CMR imaging observation unit in the emergency department reduces 1-year medical care costs in patients with acute chest pain: a randomized study for comparison with inpatient care

Abstract

Objectives: This study sought to compare the direct cost of medical care and clinical events during the first year after patients with intermediate risk acute chest pain were randomized to stress cardiac magnetic resonance (CMR) observation unit (OU) testing versus inpatient care.

Background: In a recent study, randomization to OU-CMR reduced median index hospitalization cost compared with the cost of inpatient care in patients presenting to the emergency department with intermediate risk acute chest pain.

Methods: Emergency department patients with intermediate risk chest pain were randomized to OU-CMR (OU care, cardiac markers, stress CMR) or inpatient care (admission, care per admitting provider). This analysis reports the direct cost of cardiac-related care and clinical outcomes (myocardial infarction, revascularization, cardiovascular death) during the first year of follow-up subsequent to discharge. Consistent with health economics literature, provider cost was calculated from work-related relative value units using the Medicare conversion factor; facility charges were converted to cost using departmental-specific cost-to-charge ratios. Linear models were used to compare cost accumulation among study groups.

Results: We included 109 randomized subjects in this analysis (52 OU-CMR, 57 inpatient care). The median age was 56 years; baseline characteristics were similar in both groups. At 1 year, 6% of OU-CMR and 9% of inpatient care participants experienced a major cardiac event (p = 0.72) with 1 patient in each group experiencing a cardiac event after discharge. First-year cardiac-related costs were significantly lower for participants randomized to OU-CMR than for participants receiving inpatient care (geometric mean = $3,101 vs. $4,742 including the index visit [p = 0.004] and $29 vs. $152 following discharge [p = 0.012]). During the year following randomization, 6% of OU-CMR and 9% of inpatient care participants experienced a major cardiac event (p = 0.72).

Conclusions: An OU-CMR strategy reduces cardiac-related costs of medical care during the index visit and over the first year subsequent to discharge, without an observed increase in major cardiac events. (Cost Comparison of Cardiac Magnetic Resonance Imaging [MRI] Use in Emergency Department [ED] Patients With Chest Pain; NCT00678639).

Copyright © 2011 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1. Cardiac-related cost from randomization through 1 year

This figure shows the cumulative distribution of cost by study group over 1 year. It is obtained by calculating the percentage of patients with total cost (including the index visit and follow-up cost) less than or equal to the cost specified on the x-axis. In the observation unit cardiac magnetic resonance (OUCMR) group, 79% had total costs less than $5000 compared to 58% of the inpatient care group, suggesting OUCMR is a cost-reducing care strategy.

Figure 2. Cost accumulation by month following discharge among study groups, excluding the index hospital visit cost

Mean cumulative cost by study group after hospital discharge (y-axis) is displayed by month of follow up (x-axis). Mean cumulative cost for a month is calculated as the sum of the costs across all patients up to and including that month divided by the number of patients. Observation unit cardiac magnetic resonance (OUCMR) participants had lower cost of care in the year after discharge from the index hospital visit (p=0.012). Reduced cost was the result of fewer cardiac-related emergency department visits and cardiac-related hospitalizations suggesting that an OUCMR strategy impacts care utilization after discharge.