Outcomes According to Cardiac Catheterization Referral and Clopidogrel Use Among Medicare Patients With Non-ST-Segment Elevation Myocardial Infarction Discharged Without In-hospital Revascularization

Influence of primary payer status on non-ST-segment elevation myocardial infarction: 18-year retrospective cohort national temporal trends, management and outcomes

Background

The role of insurance on outcomes in non-ST-segment-elevation myocardial infarction (NSTEMI) patients is limited in the contemporary era.

Methods

From the National Inpatient Sample, adult NSTEMI admissions were identified [2000–2017]. Expected primary payer was classified into Medicare, Medicaid, private, uninsured and others. Outcomes included in-hospital mortality, overall and early coronary angiography, percutaneous coronary intervention (PCI), resource utilization and discharge disposition.

Results

Of the 7,290,565 NSTEMI admissions, Medicare, Medicaid, private, uninsured and other insurances were noted in 62.9%, 6.1%, 24.1%, 4.6% and 2.3%, respectively. Compared to others, those with Medicare insurance older (76 vs. 53–60 years), more likely to be female (48% vs. 25–44%), of white race, and with higher comorbidity (all P<0.001). Population from the Medicare cohort had higher in-hospital mortality (5.6%) compared to the others (1.9–3.4%), P<0.001. With Medicare as referent, in-hospital mortality was higher in other {adjusted odds ratio (aOR) 1.15 [95% confidence interval (CI), 1.11–1.19]; P<0.001}, and lower in Medicaid [aOR 0.95 (95% CI, 0.92–0.97); P<0.001], private [aOR 0.77 (95% CI, 0.75–0.78); P<0.001] and uninsured cohorts [aOR 0.97 (95% CI, 0.94–1.00); P=0.06] in a multivariable analysis. Coronary angiography (overall 52% vs. 65–74%; early 15% vs. 22–27%) and PCI (27% vs. 35–44%) were used lesser in the Medicare population. The Medicare population had longer lengths of stay, lowest hospitalization costs and fewer home discharges.

Conclusions

Compared to other types of primary payers, NSTEMI admissions with Medicare insurance had lower use of coronary angiography and PCI, and higher in-hospital mortality.

Clinical Model to Predict 90-Day Risk of Readmission After Acute Myocardial Infarction

BACKGROUND

Readmissions within 30 days after acute myocardial infarction have been used as a performance metric for hospitals. However, evolving concepts of value-based reimbursement have shifted the focus to 90 days after hospital discharge. Tools are needed to determine risk for 90-day readmission to identify patients who might benefit from enhanced transitional healthcare resources.

METHODS AND RESULTS

In this cohort study, we identified all Medicare beneficiaries with a primary diagnosis of acute myocardial infarction who were discharged from hospitals participating in National Cardiovascular Data Registry ACTION registry between 2008 and 2014. Among a random 70% sample (derivation cohort), we performed hierarchical proportional hazards regression, accounting for death as a competing risk, to assess predictors of all-cause readmission within 90 days. Models were validated in the remaining 30%. Among 86 849 unique patients, 23 912 (27.5%) were readmitted within 90 days. Of the readmissions, 55% occurred within 30 days and 81% occurred within 60 days. Predictors of readmission included older age and a history of diabetes mellitus or heart failure. Coronary revascularization was associated with a lower risk of readmission. A simple risk score incorporating patient demographic and clinical characteristics known before discharge identified groups of patients with readmission risks ranging from 13.1% to 42.9%. Model discrimination was moderate (C statistic=0.662), and calibration was excellent (slope=0.97, intercept=-0.04).

CONCLUSIONS

Readmission within 90 days of hospitalization for acute myocardial infarction can be predicted by variables known before discharge and offers the potential to prospectively design transitional care to the risks of individual patients.

Outcomes According to Cardiac Catheterization Referral and Clopidogrel Use Among Medicare Patients With Non-ST-Segment Elevation Myocardial Infarction Discharged Without In-hospital Revascularization

Background

While use of P2Y12 receptor inhibitor is recommended by guidelines, few studies have examined its effectiveness among older non–ST‐segment elevation myocardial infarction patients who did not undergo coronary revascularization.

Methods and Results

We included unrevascularized non–ST‐segment elevation myocardial infarction patients ≥65 years discharged home from 463 ACTION Registry‐GWTG hospitals from 2007 to 2010. Rates of discharge clopidogrel use were described for patients with no angiography, angiography without obstructive coronary artery disease (CAD; ≥50% stenosis in ≥1 vessel), and angiography with obstructive CAD. Two‐year outcomes were ascertained from linked Medicare data and included composite major adverse cardiac events (defined as all‐cause death, myocardial infarction readmission, or revascularization), and individual components. Outcomes associated with clopidogrel use were adjusted using inverse probability‐weighted propensity modeling. Of 14 154 unrevascularized patients, 54.7% (n=7745) did not undergo angiography, 10.6% (n=1494) had angiography without CAD, and 34.7% (n=4915) had angiography with CAD. Discharge clopidogrel was prescribed for 42.2% of all unrevascularized patients: 37.8% without angiography, 34.1% without obstructive CAD at angiography, and 51.6% with obstructive CAD at angiography. Discharge clopidogrel use was not associated with major adverse cardiac events in any group: without angiography (adjusted hazard ratio [95% CI]: 0.99 [0.93–1.06]), angiography without CAD (1.04 [0.74–1.47]), and angiography with CAD (1.12 [1.00–1.25], P_interaction=0.20).

Conclusions

We found no association between discharge clopidogrel use and long‐term risk of major adverse cardiac events among older, unrevascularized non–ST‐segment elevation myocardial infarction patients. Clopidogrel use in this population requires further prospective evaluation.