Atherosclerosis Secondary Prevention Performance Measures After Coronary Bypass Graft Surgery Compared With Percutaneous Catheter Intervention and Nonintervention Patients in the Get With the Guidelines Database
Background— The American Heart Association Get With the Guidelines-Coronary Artery Disease program facilitates patient and physician compliance with proven atherosclerosis risk reduction strategies with collaborative learning sessions, teaching materials, predischarge online check lists, and web-based performance measure feedback for continuous quality improvement. Patients having coronary artery bypass graft surgery (CABG) may be subject to different care processes, nursing unit pathways, and personnel than patients having percutaneous catheter intervention or neither intervention, which may affect compliance.
Methods and Results— The Get With the Guidelines-Coronary Artery Disease database was queried to determine whether compliance with secondary prevention performance measures for CABG patients was different from that for nonsurgical patients. A total of 119 106 patients were treated with CABG (14 118), percutaneous catheter intervention (58 702), or neither intervention (46 286). Compliance with medication prescriptions, including aspirin, β-blockers, angiotensin-converting enzyme inhibitors, and lipid-lowering drugs, and smoking cessation counseling for eligible patients was analyzed. Medically appropriate exclusions and contraindications were included in the analysis. After adjusting for 14 clinical variables, CABG patients were less likely to receive most secondary prevention measures relative to percutaneous catheter intervention patients. In contrast, CABG patients were more likely to receive aspirin, β-blocker, and smoking cessation counseling than neither intervention patients. Composite adherence and defect-free rates were highest for percutaneous catheter intervention patients and lowest for neither intervention patients after adjustment.
Conclusions— There are significant differences in compliance at hospital discharge with secondary prevention performance measures for CABG patients compared with nonsurgical patients. Process of care differences may explain these differences and should be examined further because significant opportunities for improved compliance are evident. CABG patients in particular represent a group for whom secondary prevention has proven benefits, and they may benefit from future quality improvement interventions.
- secondary prevention
- CV surgery
- coronary artery disease
- catheter-based coronary interventions
Atherosclerosis risk reduction therapies can reduce early and late morbidity and mortality for patients with coronary artery disease (CAD). Since the early 1990s, the American Heart Association (AHA) has produced evidence-based guidelines on secondary prevention of atherosclerosis, providing updates as new evidence becomes available.1,2 However, in 2000, Pearson et al3 pointed out that despite a 95% awareness of guideline goals among primary care physicians caring for dyslipidemic patients, only 18% of patients were achieving goal levels of low-density lipoprotein.
As a result, programs were developed to provide a systematic approach to improving atherosclerosis secondary prevention performance measures.4 The AHA Get With the Guidelines-Coronary Artery Disease (GWTG-CAD) Program facilitates in-hospital success using a web-based patient management tool (outcome)5 and collaborative learning sessions in which hospital teams exchange best practices and learn rapid cycle improvement strategies. The patient management tool provides educational tools for patients and caregivers, as well as suggested clinical pathways and order sets to remind caregivers to institute and prescribe aspirin, β-blockers, lipid-lowering drugs, and angiotensin-converting enzyme (ACE) inhibitors, and to advise smoking cessation for appropriate patients. The patient management tool also facilitates documentation of important patient demographic and disease state information as well as performance measure compliance into the GWTG database. All of this can occur before discharge from the hospital. Online, on demand reports provide continuous quality improvement feedback to the participating institutions and permit hospitals to compare their respective performance measure improvement with other hospitals. Individual hospitals are responsible for data collection and input. Hospitals achieving the highest levels of compliance are recognized by AHA. There are no financial reward incentives directly attributable to participation, but compliance with quality performance measures can be enhanced.
Previous studies using other databases have suggested that compliance with secondary prevention performance measures for coronary artery bypass graft surgery (CABG) patients is lower than for nonsurgical patients.6 The GWTG-CAD database was queried to determine whether compliance with individual and composite atherosclerosis secondary prevention performance measures for coronary bypass graft surgery patients were different from for nonsurgical patients including those who had percutaneous catheter intervention (PCI) or neither CABG nor PCI (No-Intervention).
The study population included patients entered into the GWTG-CAD database with diagnoses of CAD, acute myocardial infarction including ST-segment and non–ST-segment elevation myocardial infarction, unstable angina, and subsequent care of myocardial infarction patients. Patients with heart failure, atrial fibrillation or syncope alone, or with a non-CAD diagnosis as the primary diagnosis were excluded from this analysis.
Performance measures were calculated for discharge medications including ACE inhibitors, aspirin, β-blocker, lipid-lowering drug, and smoking cessation advice and counseling. Performance measure compliance was analyzed using the cohort of patients eligible for the medication or counseling, excluding those patients who had a documented contraindication for the medication or were not eligible for counseling. A composite performance measure gave credit for partial patient compliance, whereas a 100% compliance performance measure required that all appropriate medications and counseling were documented for individual patients.
In the descriptive analysis, χ2 test was used for categorical variables and Kruskal–Wallis test for continuous variables to compare patient characteristics among CABG, PCI, and the No-Intervention groups. Multivariable regression analysis using generalized estimation equations was performed to determine whether CABG patients received different care from PCI or No-Intervention patients. The generalized estimation equation approach adjusts for patient demographics and baseline clinical status and considers the clustering effect within hospitals.7 A P value of <0.05 was considered significant for each test. The type-1 error (finding of false “significance”) of the whole analysis may exceed 0.05. All analyses were performed using SAS software (version 8.2; SAS Institute).
The authors had full access to and take full responsibility for the integrity of the data. All authors have read and agree to the manuscript as written.
The data collection period was from January 2000 through December 2005. A total of 119 106 patients with diagnoses of CAD, acute myocardial infarction, unstable angina, and subsequent care of myocardial infarction were analyzed. Of these, 14 118 were treated with CABG, 58 702 with PCI, and 46 286 were treated without either intervention.
The clinical characteristics of the patient groups are listed in Table 1. As expected, there were significant differences (P<0.05) between each group for all characteristics noted. The patients having No-Intervention were older and had a greater incidence of comorbid conditions compared with the CABG and PCI patients. These comorbid conditions included chronic obstructive pulmonary disease, history of heart failure, previous myocardial infarction, lower left ventricular ejection fraction, peripheral vascular disease, renal insufficiency, and previous cerebrovascular accident. Compared with PCI patients, CABG patients were older and had a greater incidence of chronic obstructive pulmonary disease, diabetes, history of heart failure, lower left ventricular ejection fraction, peripheral vascular disease, renal insufficiency, and previous cerebrovascular accident. In-hospital mortality was highest (9.21%) for the No-Intervention patients, followed by CABG (2.56%) and PCI (1.57%) patients (P<0.0001).
Performance measure compliance for each group is listed in Table 2. Univariate analysis showed that compliance was significantly (P<0.0001) lower for CABG patients compared with PCI patients for all performance measures. Compliance was significantly lower for CABG patients compared with No-Intervention patients for ACE inhibitor (57.3% versus 66.3%) but was significantly higher (P<0.0001) for aspirin (97.1% versus 94.5%), β-blocker (90.8% versus 88.2%), lipid-lowering drug (77.4% versus 72.3%), and for smoking cessation advice (82.5% versus 73.9%). Composite performance measure compliance was highest for PCI patients, followed by CABG, then No-Intervention patients at 89.5%, 86.2%, and 83.1%, respectively. Defect-free (100%) compliance was highest for PCI patients, followed by CABG, then No-Intervention patients at 71.5%, 65.1%, and 62.1%, respectively.
Multivariate analysis adjusting for the 14 clinical variables, previously noted in Table 1, confirmed that compliance with all performance measures was statistically significantly higher for PCI patients than for CABG patients (Table 3) for ACE inhibitor, aspirin, lipid-lowering drug, smoking cessation advice, and composite 100% compliance but not for β-blocker (P=0.55). Similar comparisons for CABG patients versus No-Intervention patients showed significantly higher (P<0.05) compliance for aspirin, β-blocker, and smoking cessation advice but lower for ACE inhibitor. There was no difference for lipid-lowering drug or defect-free 100% compliance.
Gender differences were noted between groups and are depicted in the Figure. Males were more likely to receive medications and defect-free care, whereas females were more likely to receive smoking cessation advice. However, the adjustment model included gender, such that the differences in conformity with performance measures between the intervention groups are independent of gender. There were no significant interactions between gender and the intervention groups for the aspirin, smoking cessation, lipid-lowering drug, and 100% compliance composite measures. There was a significant interaction for the ACE inhibitor and β-blocker measures by gender, but these differences were small. There were also no interactions between race and the intervention groups for ACE inhibitor, β-blocker, smoking cessation, low-density lipoprotein treatment, and 100% compliance composite performance measures. The aspirin use measure was slightly different across whites and nonwhites.
The presence or absence of contraindications to administration of the specific drugs is noted in Table 4. The No-Intervention patients had a far greater percentage of patients for whom the presence or absence of a contraindication was unknown for each performance measure. The percentage of unknowns was similar between the CABG and PCI groups, whereas the presence of a contraindication was higher for the CABG group compared with the PCI group for each performance measure. For the data analyses described above, unknowns were included in the no contraindication denominator.
The benefits of secondary prevention in all patients with CAD have been clearly demonstrated. The importance of instituting appropriate and effective secondary prevention measures after CABG has been emphasized to the surgical community initially in the form of editorial comment on atherosclerosis risk reduction guidelines and manuscripts,8,9 as well as later American College of Cardiology (ACC)/AHA and as Society of Thoracic Surgeons guidelines specifically directed toward CABG patients.10,11 Furthermore, the National Quality Forum has specifically included discharge aspirin, β-blocker, and lipid-lowering drugs as quality indicators after CABG.
Foody et al6 compared CABG patients with non-CABG patients in a Centers for Medicare and Medicaid Services National Heart Care Project database, including >37 000 patients with a discharge diagnosis of acute myocardial infarction, collected between April 1998 and March 1999. Performance measure compliance for CABG patients was higher for aspirin (88% versus 83%) but lower for β-blockers (61.5% versus 72.1%), ACE inhibitors (55.5% versus 72.1%), and lipid-lowering drugs (34.7% versus 55.7%). Our data included all patients enrolled by participating hospitals and represented a younger group of patients during a later time period than the Foody study, which probably accounts for higher compliance rates seen in all groups. In addition, hospitals participating in GWTG-CAD have the necessary tools and achievement incentives to reach higher levels of performance measure compliance.
More recently, there have been carefully focused programs aimed at improving performance measure compliance for patients after CABG. The Alabama Coronary Artery Bypass Grafting Project, a voluntary statewide process-oriented quality improvement initiative, demonstrated improvement in aspirin at discharge rates from 87% to 100% over a 6-year period (phases I and II) as well as β-blocker (65% to 78%) and lipid-lowering drug (36% to 95%) over a 2-year period (phase II). There was wide variability noted among the 21 hospitals performing CABG surgery.12 The University of Kentucky instituted an intensive educational and process-oriented quality improvement initiative based on the 2001 ACC/AHA secondary prevention guidelines13 and compared performance measures before and after institution of the program. Compliance rates improved significantly (P<0.05) for aspirin at discharge (92% to 100%), ACE inhibitor (42% to 84%), lipid-lowering drug (76% to 96%), smoking cessation counseling (0% to 100%), and dietary counseling (49% to 91%). β-Blocker use improved from 95% to 100%.14
There are clear limitations of this study, many of which relate to the nature of the observational database for which contributions are voluntary, for which there is limited audit, and for which on-site data collection and contribution processes may or may not be similar between hospitals as well as within each hospital. In most hospitals, CABG patients are cared for in different nursing units, by different nursing personnel, and using different clinical pathways than those patients having either PCI or No-Intervention. It is also likely that the No-Intervention patients had different care processes than PCI patients. No-Intervention patients had additional comorbid conditions that may have made either CABG or PCI not indicated because of high risk or patient preference. In addition, there may have been comorbid conditions that were the primary reason for hospitalization and in a care area different from the usual PCI or CABG care areas of the hospital. However, each of these differences could affect the compliance success as well as the recording of medically appropriate contraindications to specific medications. We could not determine the impact of these potential differences from the information contained in the GWTG-CAD database.
There are clear differences in performance measure compliance between CABG patients compared with PCI and No-Intervention patients. Opportunities for improvement are evident in each patient group. However, the opportunities for CABG patients would seem to be more readily achievable given the generally uniform care processes applied to CABG patients, who are usually hospitalized for a longer time period than PCI patients and who usually experience a greater disruption of their lives, both from an individual standpoint and the standpoint of their families. Whether a more focused GWTG program should be directed toward CABG patients and would improve performance measure compliance is the subject of additional investigation, although reports noted above suggest that higher performance measure compliance rates are achievable. More focused work to create standardized processes and improve performance measure compliance across the entire spectrum of CAD patients is clearly warranted.
Presented at the American Heart Association Scientific Sessions, Chicago, Ill, November 12–15, 2006.
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