Predictors of Cardiac Rehabilitation Referral in Coronary Artery Disease Patients:Results From the AHA’s Get With the Guidelines Program

Todd M. Brown, MD;1 Adrian F. Hernandez, MD, MHS;2 Vera Bittner, MD, MSPH;1 Christopher P. Cannon, MD;3 Gray Ellrodt, MD;4 Li Liang, PhD;2 Eric D. Peterson, MD, MPH;2 Ileana L. Piña, MD;5 Monika M. Safford, MD;1 Gregg C. Fonarow, MD6

1University of Alabama at Birmingham, Birmingham, AL; 2Duke Clinical Research Institute, Durham, NC; 3Brigham and Women’s Hospital, Boston, MA; 4Berkshire Medical Center, Pittsfield, MA; 5Case Western Reserve University, Cleveland, OH; 6UCLA Medical Center, Los Angeles, CA

Results

DISCLOSURE INFORMATIONThe following relationships exist related to this presentation:The GWTG-CAD program is supported by the American Heart Association which received funding from the Merck-Schering Plough Partnership

Table 1. Baseline Demographic and Clinical Characteristics in the Overall Population and in Those Referred and Not Referred to Cardiac Rehabilitation

Overall

Population

(n=185,794)

Not Referred

to CR

(n=115,231)

Referred

to CR

(n=70,563)

P-Value

Age (years)

Gender (%)

Male

Race (%)

White

African American

Hispanic

Body Mass Index (kg/m2)

Ejection Fraction (%)

Diabetes (%)

Hypertension (%)

Dyslipidemia (%)

Heart Failure (%)

Admitting Diagnosis (%)

Heart Failure with CAD

STEMI

Non-STEMI

Unspecified MI

Unstable Angina

CAD

65.6 ± 13.6

62.6

73.1

8.2

7.2

29.1 ± 6.9

47.8 ± 14.8

32.7

65.3

42.2

19.1

17.4

5.9

10.9

42.9

6.8

16.2

66.9 ± 13.9

59.9

69.3

9.1

8.2

28.9 ± 7.1

47.0 ± 15.5

34.6

65.7

37.6

24.3

25.7

4.5

9.9

40.1

6.3

13.5

63.5 ± 12.7

67.1

79.2

6.7

5.6

29.3 ±6.4

49.0 ± 13.7

29.6

64.6

49.8

10.5

3.8

8.2

12.4

47.5

7.6

20.5

<0.001

<0.001

<0.001

<0.001

<0.001

<0.001

<0.001

<0.001

<0.001

<0.001

All values listed as mean ± standard deviation or %.

Wilcoxon two-sample test performed for continuous variables.

Chi-square test performed for categorical variables.

CAD=coronary artery disease, CR=cardiac rehabilitation, MI=myocardial infarction, STEMI=ST segment elevation myocardial infarction

Table 3. Independent Predictors of Referral to Cardiac Rehabilitation in the Overall Population

VariableAdjusted Odds Ratio (95% CI)

VariableAdjusted Odds Ratio (95% CI)

Age (per 10 years)

Gender

Male

Female

Race

White

Hispanic

African American

Admitting Diagnosis

Heart Failure with CAD

STEMI

Non-STEMI

CAD

Unspecified MI

Unstable Angina

0.93 (0.92-0.95)

Referent

0.89 (0.85-0.93)

Referent

0.93 (0.86-1.00)

0.91 (0.85-0.98)

Referent

3.66 (2.03-6.58)

3.55 (1.93-6.50)

3.47 (1.87-6.43)

3.26 (1.89-5.63)

2.41 (1.40-4.15)

ST elevation/LBBB

BMI (per 5 units)

DC SBP (per 10 units)

Teaching Hospital

Co-morbidities

Dyslipidemia

Current Smoker

COPD

PAD

Prior MI

CRI

Atrial Fibrillation

Heart Failure

Stroke or TIA

Chronic Dialysis

1.26 (1.15-1.38)

1.02 (1.01-1.03)

0.98 (0.96-0.99)

0.26 (0.09-0.80)

1.20 (1.10-1.30)

1.08 (1.03-1.12)

0.93 (0.88-0.98)

0.92 (0.86-0.98)

0.91 (0.86-0.96)

0.91 (0.86-0.97)

0.90 (0.83-0.99)

0.89 (0.82-0.97)

0.87 (0.82-0.92)

0.67 (0.56-0.80)

The variables listed above are the statistically significant factors predicting CR referral in the final, reduced multivariable model.

BMI=body mass index, CAD=coronary artery disease, CI=confidence interval, COPD=chronic obstructive pulmonary disease, CRI=chronic renal insufficiency, DC=Discharge, LBBB=left bundle branch block, MI=myocardial infarction, PAD=peripheral arterial disease, SBP=systolic blood pressure, STEMI=ST segment elevation myocardial infarction, TIA=transient ischemic attack

• A significant number of Coronary Artery Disease (CAD) patients who qualify for Cardiac Rehabilitation (CR) are not referred despite proven reductions in mortality and national guideline recommendations.• The patient specific factors associated with referral to CR are not well understood.

Background

• To determine the patient specific factors which independently predict referral to CR in the AHA’s Get with the Guidelines (GWTG) CAD Program.

Objective

• Study population: 185,794 patients in the AHA’s GWTG Program admitted for CAD between January 2000 and September 2007 who were discharged home alive.• GWTG participating hospitals submit in-hospital clinical information using an internet-based tool. Data are abstracted by trained personnel.• We calculated the proportion of patients referred to CR in the overall population, in those admitted with myocardial infarction, and in those who had a myocardial infarction, percutaneous coronary intervention, or coronary artery bypass graft surgery.• To determine which factors independently predicted CR referral in the overall population, we performed multivariable logistic regression using the generalized estimating equations method to adjust for in-hospital clustering.• Outcome variable: referral to CR

We considered missing values, failure to document whether referral was made, and documentation that CR was “not applicable” to be non-referred for this analysis.

• Predictors of CR referral: The initial model included age, gender, race, body mass index, discharge systolic blood pressure, admitting diagnosis, ST segment elevation/LBBB on initial EKG, medical co-morbidities, insurance status, and hospital characteristics. Non-statistically significant predictors (p>0.1) were removed to create the final, reduced model.

Methods

Conclusions• Overall, only 38% of patients admitted to GWTG participating hospitals with a CAD-related diagnosis, 43% admitted with a myocardial infarction, and 46% with a myocardial infarction, percutaneous coronary intervention, or coronary artery bypass graft surgery were referred to CR.• In the overall population, both patient and hospital factors were independently associated with lower odds of CR referral:

Patient:• Demographics (older age, women, minorities)• Medical conditions (poorly controlled blood

pressure, a heart failure admitting diagnosis, most co-morbid diseases)

Hospital type (teaching hospitals)

Table 2. Number and Percent of Patients Referred to Cardiac Rehabilitation

Not Referred to CR Referred to CR

Overall Population (n=185,794)

Patients with MI (n=110,905)

Patients with MI, PCI, or CABG (n=144,281)

115,231 (62%)

62,849 (57%)

78,275 (54%)

70,563 (38%)

48,046 (43%)

66,006 (46%)

CABG=coronary artery bypass graft surgery, CR=cardiac rehabilitation, MI=myocardial infarction, PCI=percutaneous coronary intervention.

• Participation in the GWTG program is voluntary. The overall proportion of eligible patients who are referred to CR and the predictors of CR referral may not be the same in non-participating hospitals.• We considered individuals with missing data for CR referral, lack of documentation of CR referral, and documentation that CR was “not applicable” as not being referred for the purpose of this analysis. This may have resulted in an underestimation of the proportion of eligible patients referred to CR.• The GWTG program only collects in-hospital data. Therefore, we are unable to capture patients who are referred to CR following discharge from the hospital or assess what proportion of referred patients actually attend CR.• Data on patient socioeconomic status was not available.

Limitations