naaso october 2003
TRANSCRIPT
Body Mass Index Does Not Discriminate Coronary Revascularization in Post-Cardiac Rehab Patients1
Robert C. Lowe, Wellness Research Center, University of Central Florida, Orlando, FL [email protected] 407-823-4470
ABSTRACT
An increased body mass index (BMI) may confer cardioprotective benefits in some patients following coronary revascularization (CR) procedures. In addition, there appears to be a differential effect of BMI on the short and long-term outcomes of this patient population. The purpose of this investigation was to examine the relationship between BMI and CR in a group of post-cardiac rehabilitation patients. Eighty-six post-cardiac rehab patients (62±11 yr) with an average BMI of 27±4 participated in this study. The average length of time since completion of cardiac rehab was 3.8±2 yr. Patients were classified as either receiving or not receiving CR (CABG or PTCA) during this follow-up period. The influence of total cholesterol (TC), BMI, systolic blood pressure (SBP), diastolic blood pressure (DBP), and length of time since completion of cardiac rehab (TIME) were analyzed using Discriminant Function Analysis (DFA; SPSS 11.0.1). Pooled within group correlations between discriminating variables and standardized canonical discriminant functions revealed only DBP and TIME were highly correlated (0.847 and 0.597, respectively). Therefore, BMI, TC, and SBP were dropped from the model. The resulting model: CR = -7.228 + 0.803(TIME) + 0.520 (DBP) correctly classified CR 82.6% of the time. The results suggest that BMI may not be important in predicting whether or not post-cardiac rehab patients receive CR. Further, only TIME and DBP significantly contributed to the prediction of CR in this group of post-cardiac patients.
METHODS
Eighty-six post-cardiac rehab patients (62±11 yr) with an average BMI of 27±4 participated in this study. The average length of time since completion of cardiac rehab was 3.8±2 yr. Patients were classified as either receiving or not receiving CR (CABG or PTCA) during this follow-up period. The influence of total cholesterol (TC), BMI, systolic blood pressure (SBP), diastolic blood pressure (DBP), and length of time since completion of cardiac rehab (TIME) were analyzed using Discriminant Function Analysis (DFA; SPSS 11.0.1).
RESULTS
Pooled within group correlations between discriminating variables and standardized canonical discriminant functions revealed only DBP and TIME were highly correlated (0.847 and 0.597, respectively). Therefore, BMI, TC, and SBP were dropped from the model. The resulting model: CR = -7.228 + 0.803(TIME) + 0.520 (DBP) correctly classified CR 82.6% of the time.
INTRODUCTION
An increased body mass index (BMI) may confer cardioprotective benefits in some patients following coronary revascularization (CR) procedures. In addition, there appears to be a differential effect of BMI on the short and long-term outcomes of this patient population. The purpose of this investigation was to examine the relationship between BMI and CR in a group of post-cardiac rehabilitation patients.
SUMMARY
The results suggest that BMI may not be important in predicting whether or not post-cardiac rehab patients receive CR. Further, only TIME and DBP significantly contributed to the prediction of CR in this group of post-cardiac patients.
1This data was collected over 8 years from participants in the Baptist Health Cardiac Rehab Program, Little Rock, Arkansas.
TABLE 1: Descriptive Statistics
86 18.74 19.25 37.99 26.9181 4.37207
74 50.0 50.0 100.0 76.811 8.4977
86 4 1 5 2.42 1.057
86 7 1 8 3.79 2.018
75 100.00 90.00 190.00 134.0933 16.70505
65 244.00 112.00 356.00 202.0000 37.87521
58
BMI
DBP
FREQTIME
SBP
TC
Valid N (listwise)
N Range Minimum Maximum Mean Std. Deviation
TABLE 2: Tests of Equality of Group Means
.999 .045 1 56 .833
.736 20.109 1 56 .000
.974 1.480 1 56 .229
.999 .029 1 56 .866
.997 .175 1 56 .677
.848 10.002 1 56 .003
BMI
TIME
FREQ
TC
SBP
DBP
Wilks'Lambda F df1 df2 Sig.
TABLE 3: Structure Matrix
.847
.597
.230
.079
-.040
.032
TIME
DBP
FREQ
SBP
BMI
TC
1
Function
Pooled within-groups correlations between discriminatingvariables and standardized canonical discriminant functions Variables ordered by absolute size of correlation within function.
TABLE 4: Classification Results a
61 6 67
9 10 19
91.0 9.0 100.0
47.4 52.6 100.0
INTERVENNone
Revascularization
None
Revascularization
Count
%
OriginalNone
Revascularization
Predicted GroupMembership
Total
82.6% of original grouped cases correctly classified.a.