Association of Cardiac Rehabilitation With Survival Among US Veterans

IMPORTANCE Participation in cardiac rehabilitation (CR) programs at Veterans Affairs (VA) facilities is low. Most veterans receive CR through purchased care at non-VA programs. However, limited literature exists on the comparison of outcomes between VA and non-VA CR programs. OBJECTIVE To compare 1-year mortality and 1-year readmission rates for myocardial infarction or coronary revascularization between VA vs non-VA CR participants. DESIGN, SETTING, AND PARTICIPANTS This cohort study included 7320 patients hospitalized for myocardial infarction or coronary revascularization at the VA between 2010 and 2014 who did not die within 30 days of discharge and who participated in 2 or more CR sessions after discharge. The study excluded individuals hospitalized for ischemic heart disease after December 2014 when the VA Choice Act changed referral criteria for non-VA care. Data analysis was performed from November 2019 to January 2020. EXPOSURES Participation in 2 or more CR sessions within 12 months of discharge at a VA or non-VA facility.


Introduction
Cardiac rehabilitation (CR) is a multidisciplinary secondary prevention program aimed at reducing cardiovascular risk in patients with preexisting heart disease. Exercise-based CR has been shown to reduce cardiovascular-associated mortality and hospitalizations and improve quality of life in patients with coronary heart disease. 1,2 Referral to CR is a class I recommendation from the American Heart Association and the American College of Cardiology for patients with recent myocardial infarction (MI), percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG), chronic stable angina, or heart failure. [3][4][5] Historically, participation in CR programs in the US Department of Veterans Affairs (VA) has been reported to be low among patients with ischemic heart disease, with substantial geographic variation across the country. [6][7][8] The VA is adopting innovative means to improve CR participation; however, because not all VA facilities offer CR and a large proportion of veterans live far from a VA facility, referral to a CR program outside the VA (non-VA CR) is a common practice. Evaluation of CR outcomes in the VA (including non-VA referrals) is important to inform policy decisions and clinical care, particularly in the setting of recent changes in VA policy resulting in a potential increase in the use of community care referrals for health care in the VA.
Limited literature currently exists on the comparison of outcomes between VA-delivered and non-VA (purchased community care) CR programs. Therefore, we conducted a cohort study using the national VA electronic health record to compare 1-year all-cause mortality and 1-year readmission rates for non-fatal MI, PCI, and/or CABG among veterans attending VA and non-VA CR programs.

Methods
This study was approved by the San Francisco Veterans Health Administration and University of California, San Francisco institutional review boards. The requirement for informed consent was waived because the research involved no more than minimal risk to the participants, the waiver did not adversely affect the rights or welfare of the participants, and the research could not practicably be performed without the waiver. This study follows the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) reporting guideline for cohort studies. Patients who died within 30 days of discharge were excluded from the analysis. Among the remaining patients, we identified those who participated in 2 or more CR sessions within 12 months of discharge using CPT codes 93797, 93798, S9472, S9473, G0422, and G0423 and classified them as CR participants. Because visits and intake sessions without any exercise are often recorded using the same codes as those with exercise training, we required 2 or more encounters associated with the CR codes to qualify as participation to ensure at least 1 session of exercise training and/or behavioral education. Patients hospitalized for MI, PCI, or CABG between 2010 and 2014 who had only 1 or no CR sessions within 12 months of discharge were excluded from the analysis. Any CR encounters obtained from the VA outpatient tables were classified as VA CR, whereas those obtained from Fee Basis files (containing information about health care visits outside the VA that were paid

Statistical Analysis
Baseline characteristics of participants were compared using χ 2 tests for categorical variables and 2-sided t tests for continuous variables, with P < .05 considered statistically significant. Stabilized propensity weights were generated for VA CR vs non-VA CR participants using data on patient demographic characteristics, regional distribution, indication for CR, and comorbid conditions. We used Cox proportional hazards models with inverse probability treatment weighting to compare mortality and readmissions for VA CR participants with those for non-VA CR participants. Sensitivity analysis was performed by stratifying participants into 2 groups according to time to first CR session from discharge (0-6 months vs >6 months) and then comparing mortality and readmission outcomes between VA and non-VA CR participants within the 2 strata. All statistical analyses were performed   (Figure 1A and Table 3). Rates of readmission for MI or revascularization during the 12 months after discharge were 4.9% among VA participants vs 4.4% among non-VA CR participants (HR, 1.06; 95% CI, 0.83-1.35; P = .62) ( Figure 1B and Table 3). Separate Cox proportional hazard models estimating the hazard of readmission for MI and CABG did not show any statistically  significant difference between the 2 groups; however, the hazard of 1-year readmission for PCI was higher among VA CR participants than non-VA CR participants (HR, 1.45; 95% CI, 1.08-1.94; P = .01).

JAMA Network Open | Cardiology
On stratifying patients by time from discharge to first CR session, we found that 6561 patients (89.6%) started CR within 6 months of discharge and the remaining 759 patients (10.3%) started CR after 6 months. We found no differences in 1-year mortality (HR, 1.33; 95% CI, 0.90-1.97; P = .15) or 1-year overall readmission (HR, 1.06; 95% CI, 0.82-1.35; P = .66) rates for MI or revascularization between VA and non-VA CR participants in either strata (Table 3). Figure 2 shows the probability of mortality at 1 year according to the number of CR sessions.

Discussion
Among patients who were hospitalized at a VA facility between 2010 and 2014 for MI, PCI, or CABG, only 8.7% participated in CR, with 39.9% of participants attending VA-delivered CR programs and 60.1% attending non-VA (purchased care) CR programs. Black and Hispanic veterans were more likely to attend VA CR, whereas white veterans were more likely to attend non-VA CR, suggesting that VA-delivered care may address some of the racial and ethnic disparities seen in prior studies. There were no statistically significant differences in rates of 1-year mortality or 1-year overall readmissions for major adverse cardiovascular events between those who attended CR in VA vs non-VA settings.
These findings highlight the need to redouble efforts to improve participation in CR, regardless of where it is provided, among eligible patients with ischemic heart disease.   Prior studies 1,2,[9][10][11][12][13][14][15] have established the association of CR with reduced cardiovascular mortality.
Several studies [16][17][18][19][20][21][22][23] have compared the quality of care between VA and non-VA settings; however, to our knowledge, this study is the first to compare outcomes of CR between VA and non-VA facilities.
A systematic review comparing the quality of VA and non-VA care found that mortality outcomes were comparable between the 2 settings or favored VA care, depending on the condition studied. 21 A study 22 from 2007 found higher mortality rates in VA facilities among patients who underwent revascularization procedures. However, 2 newer studies 20,24 looking at 30-day mortality outcomes found that compared with non-VA care, VA care was associated with better survival among patients hospitalized for MI or PCI. One study 20 found higher readmission rates for MI in the VA compared with non-VA hospitals.
Given the heterogeneity in outcomes between VA and non-VA care, it is reassuring to find that participation in CR programs in either setting is associated with similar all-cause mortality and overall readmission rates for MI or revascularization. This is particularly relevant in light of the fact that most VA medical centers do not have on-site CR programs, necessitating referral to non-VA programs. 7,8 In addition, a qualitative study 25 looking at barriers to CR participation in the VA found that the most common reason for refusal was patient transportation issues. Because there is discussion around expanding community care in the VA alongside the impetus to increase CR participation, our research can help inform both practitioner and patient decisions around referral to CR.
Our results included a higher probability of 1-year readmission for PCI among VA CR participants than non-VA CR participants. However, our analysis only captured readmissions at VA hospitals or non-VA hospitals that were reimbursed by the VA. Veterans who attended non-VA CR may have been more likely than those who attended VA CR programs to have rehospitalizations covered through private insurance or Medicare, in which case we could have undercounted readmissions in the non-VA care group. Given that the mortality rates and 1-year MI readmission rates were similar between the 2 groups, the finding that VA CR participants were readmitted more often for PCI (at VA facilities or those reimbursed by the VA) should not be viewed as an indicator of a worse health outcome.

Limitations
There are several limitations to our study. Because we used electronic health records to obtain nationwide data for this study, we were unable to account for intangible factors, such as patient motivation and psychological factors that play an important role in CR participation and completion.
We were also unable to account for data such as numbers of vessels revascularized, ejection fraction, or medication adherence, which are important measures of disease severity. However, we adjusted for CR indication and traditional risk factors for cardiovascular disease, which would, in part, reflect No. of CR sessions7 -12 Adjusted marginal probability of 1-year mortality (line) with 95% CIs (shaded areas), by number of CR sessions attended.