Participation in cardiac rehabilitation is associated with reductions in mortality and recurrent myocardial infarction. Taylor et al, in a meta-analysis of randomized clinical trials of exercise based cardiac rehabilitation, demonstrated that participation in cardiac rehabilitation was associated with significant reductions in both all-cause mortality (OR 0.80, 95% CI 0.68–0.93) and cardiac-specific mortality (OR 0.74, 95% CI 0.61–0.96) after a median follow-up of 15 months (22
). Witt and colleagues have subsequently extended these data by demonstrating that participation in contemporary, community-based cardiac rehabilitation programs, which enroll older and higher risk patients not enrolled in clinical trials and provide more comprehensive approaches to secondary prevention in addition to exercise training, is associated with reduced mortality and fewer recurrent myocardial infarctions (23
). Despite these proven benefits of cardiac rehabilitation, previous studies from predominantly single centers within the United States report referral rates of less than 25–30% (11
). In our study, only approximately one-half of eligible patents in this large, nationwide sample of 72,817 patients discharged from 156 GWTG participating hospitals were referred to cardiac rehabilitation. We also observed substantial variation among hospitals in the percentage of eligible patients referred to cardiac rehabilitation. In 35% of hospitals, fewer than 20% of eligible patients were referred, while only one-third referred over 60%. Given that GWTG hospitals in general (24
), as well as the subset of those hospitals included in this analysis, report very good compliance with virtually all other secondary prevention performance measures, we believe our results represent a best case scenario among hospitals with high adherence rates to core measures and sufficient resources for excellent data collection.
We also observed that individuals not referred to cardiac rehabilitation were less likely to have received other guidelines-based therapies as defined by recent performance measures (20
). Individuals not referred to cardiac rehabilitation were less likely to be discharged on aspirin, beta-blockers, angiotensin converting enzyme inhibitors or angiotensin receptor blockers if they had left ventricular systolic dysfunction, to receive lipid lowering agents if they had a low density lipoprotein cholesterol level >100 mg/dL, and to receive smoking cessation counseling. Most concerning, however, is that despite the wealth of data on the benefits of cardiac rehabilitation, the overall referral rate to cardiac rehabilitation (56%) was far lower than for any of the other performance measures studied (which ranged from 84–98%), suggesting that physician awareness about the benefits of cardiac rehabilitation is lower than for other interventions.
Cortes and Arthur recently systematically reviewed 10 studies to examine referral patterns to cardiac rehabilitation (17
). Major predictors of referral to cardiac rehabilitation included being English speaking, admitted to a hospital with a cardiac rehabilitation program, insurance status, and previous myocardial infarction. Other less significant predictors included younger age, cardiac catheterization, hypercholesterolemia, CABG surgery, hypertension, and smoking (17
). Our results are similar. Younger age, ST-segment elevation myocardial infarction, and the performance of PCI or CABG surgery were associated with increased odds of cardiac rehabilitation referral. Individuals with dyslipidemia and those who smoked also had increased odds of cardiac rehabilitation referral; in contrast, most co-morbidities were associated with lower odds of referral. Individuals with co-morbidities may be perceived by physicians as less likely to benefit or less likely to participate in cardiac rehabilitation; however, in many instances, these individuals represent populations at significantly increased cardiovascular risk who may benefit from the more intense secondary prevention services provided in cardiac rehabilitation (23
). A recent analysis examining patient and physician factors affecting cardiac rehabilitation referral concluded that among physicians, one of the most important factors influencing whether physicians refer patients to cardiac rehabilitation was the degree of the physician’s perceived benefit of cardiac rehabilitation (26
). Therefore, increased physician awareness about the benefits of cardiac rehabilitation in these higher risk sub-groups may increase referrals.
Obviously, individuals cannot enroll and participate in cardiac rehabilitation if they are not first referred. Mazzini et al report that, in a single center using a GWTG-based clinical pathway, 55% of patients with myocardial infarction were referred to cardiac rehabilitation at discharge (27
). However, the subsequent enrollment rate into cardiac rehabilitation for these individuals who were referred prior to discharge was only 34% (27
). With no more than one-half of eligible patients being referred and only one-third of those referred enrolling, it is not surprising that most studies, including a recent analysis of 267,427 Medicare beneficiaries with acute myocardial infarctions or CABG surgery, report overall enrollment rates into cardiac rehabilitation of only about 15–20% (9
). One notable exception is Olmsted County, Minnesota where 55% of individuals enrolled into cardiac rehabilitation following a myocardial infarction between 1982 and 1998 (2
). Numerous barriers exist which prevent referred patients from enrolling into cardiac rehabilitation including cost, lack of insurance coverage, time commitment, and distance from a cardiac rehabilitation center. However, despite these barriers, simply increasing the proportion of eligible patients referred to cardiac rehabilitation, as recommended by numerous ACC/AHA guidelines (4
) and a recently published AACVPR/ACC/AHA performance measure (18
), could substantially increase cardiac rehabilitation enrollment.
Investigators in Canada have examined the effectiveness of computer generated, automatic referral at discharge of eligible patients to cardiac rehabilitation (28
). These authors report enrollment rates into cardiac rehabilitation ranging from as low as 43% to as high as 73% (28
). These data support the hypothesis that failure to refer patients to cardiac rehabilitation represents one of the largest and, potentially, most easily overcome barrier to participation in cardiac rehabilitation. By simply increasing referral rates, these authors report much higher rates of enrollment in cardiac rehabilitation than is reported using standard, physician-initiated referral practices. However, automatically referring patients to cardiac rehabilitation may not be enough. Mazzini et al report that among those who were referred to cardiac rehabilitation but did not enroll, 26% reported that they did not perceive that they had been referred (27
), reflecting a gap between what is documented in the medical record and what the patient actually recalls following discharge. Additionally, multiple previous studies have demonstrated that physician endorsement of the benefits of cardiac rehabilitation is one of the most powerful predictors of attendance in cardiac rehabilitation among patients who are referred (13
). Therefore, a computer generated referral, although helpful in prompting physicians to initiate referrals, may not be sufficient to correct the current vast underutilization of cardiac rehabilitation.
Our study has a number of limitations. First, hospital participation in the GWTG program is voluntary. Therefore, the overall proportion of eligible patients referred to cardiac rehabilitation and predictors of referral may not be the same in non-participating hospitals. Furthermore, even among participating hospitals, we are not able to determine the referral patterns of those hospitals with a large amount of missing data about cardiac rehabilitation referral. This does limit the generalizabilty of our findings; however, we are unlikely to have underestimated the proportion of eligible patients referred to cardiac rehabilitation in the United States. Rather, we believe that our results represent a best case scenario among hospitals with high adherence rates to core measures in general. Hospitals excluded from our analysis as well as non-GWTG participating institutions very likely refer a lower proportion of eligible CAD patients to cardiac rehabilitation. Therefore, the overall referral rate within the United States is likely lower than what we estimate in this analysis. Second, the GWTG program only collects in-hospital data and does not collect data on physician characteristics. Therefore, we are unable to assess what proportion of individuals are referred to cardiac rehabilitation following discharge from the hospital or what percentage of those referred actually attend cardiac rehabilitation. Furthermore, we are unable to determine what physician characteristics contribute to cardiac rehabilitation referral. Third, we lack detailed data on socioeconomic variables such as income and education levels of eligible patients, which prohibits us from assessing the impact that these variables have on referral rates. Fourth, we cannot exclude residual measured and unmeasured confounding variables that might account for these associations with cardiac rehabilitation referral.
Overall, only approximately one-half of patients discharged from these GWTG participating hospitals who were eligible for cardiac rehabilitation following a myocardial infarction, PCI, or CABG surgery were referred at hospital discharge. Older individuals, as well as those with most of the co-morbidities we studied had decreased odds of cardiac rehabilitation referral. Individuals with ST-segment elevation myocardial infarction or who underwent PCI or CABG surgery had increased odds for referral. More emphasis on increasing referral to cardiac rehabilitation is necessary to overcome the current underutilization of cardiac rehabilitation in the secondary prevention of cardiovascular disease.