BACKGROUND: We evaluated the effectiveness of a low-cost group visit intervention for changing the dietary intake and lipid levels of patients with known coronary artery disease (CAD).
METHODS: We performed a controlled random group assignment trial in 4 community outpatient clinics. The Dietary Intervention and Evaluation Trial randomized 97 patients with CAD to either a control group that followed the National Cholesterol Education Program’s Step II-III diet plan (n=48) or an experimental group that received meal plans, recipes, and nutritional information during monthly group office sessions (n=49). Both groups received lipid-lowering medications and were followed-up over 12 months. We assessed dietary intake, fasting lipid profiles, hemoglobin A1C levels, and per member per month (PMPM) expense data.
RESULTS: Food frequency data showed that eating fruits and vegetables and cooking with monounsaturated fat increased significantly in the experimental group compared with the control group at 1 year (P=.0072; P=.0001; P=.0004). The total PMPM expenses decreased for both groups (38% for the experimental group and 10% for the control group), but the cost difference was statistically nonsignificant (P=.2975). Both groups noted low-density lipoprotein reductions, significant only in the experimental group (P=.0035).
CONCLUSIONS: Our study suggests that using group office visits for patients with CAD was an effective method for helping subjects make dietary changes and for improving lipid levels. Patients with known CAD and elevated lipid levels were willing to make significant lifestyle changes when offered a program that emphasizes healthy foods in a group visit format.
It is well established that nearly half of all Americans will die of cardiovascular disease. Lipid-lowering trials1,2 using medications have resulted in 30% reductions in mortality and morbidity. Although effective, nearly 70% of the morbidity and mortality from coronary artery disease (CAD) occurs in patients receiving lipid-lowering therapy, despite highly significant 30% to 35% low-density lipoprotein (LDL) level reductions. Additional interventions beyond medication-induced LDL reductions appear warranted if our health care system is to further reduce the morbidity, mortality, and expenses associated with CAD. Nutritional choices have been shown to beneficially influence several CAD risk factors.3
Physicians need low-cost, practical, and effective dietary programs that patients with CAD are willing to follow. In particular, there is a need to explore simple dietary interventions that influence the pathophysiology behind CAD. Fortunately, there is growing interest in dietary intake that has been shown to decrease LDL oxidation4-7 and to improve endothelial vasomotion. For example, it has been shown in patients in France with known CAD that simply switching polyunsaturated fat intake to largely oxidation-stable monounsaturated fat intake and n-3 fatty acid intake (omega-3 fats) reduces total mortality by 70% without reductions in total fat intake or changes in lipid profiles.9,10 Other observational studies have supported the concept that the type of fat intake is more important than reducing total fat intake.11,12
The objectives of the Dietary Intervention and Evaluation Trial (D.I.E.T.) were to add healthy foods to the diet (eg, legumes, fruits, and vegetables) and to change dietary fat intake from polyunsaturated and saturated fat to oxidation-resistant monounsaturated fat and n-3 fatty acid sources. In essence, we assessed the willingness of Americans with CAD to move toward a more Mediterranean-like diet. The subjects were counseled during group office visits. The mechanism for physicians to offer group visits as a billable service is reviewed elsewhere.13
Methods
Study Sample
In January 1997, patients with CAD were selected from the Heart Care Registry at Group Health Cooperative at 4 multispecialty clinics in 3 cities. Inclusion criteria were known CAD (based on hospital-generated diagnostic coding data and a subsequent chart review confirmation) and either LDL levels greater than 3.4 mmol per L (130 mg/dL) or patients without an LDL level recorded in the previous 18 months but with a total cholesterol/high-density lipoprotein (HDL) ratio greater than 5.5. We enrolled patients with high lipid levels in an attempt to choose patients at the greatest need for intervention. The Center for Health Studies contacted 234 patients by telephone and successfully recruited 132 with known CAD to participate in our study (56% willingness to enroll). Primary care physicians excluded 11 patients with terminal or end-stage medical problems who were not likely to survive the duration of the study. One patient who was following another dietary program (the Ornish Program) was excluded, resulting in 120 remaining subjects. Anticipating a 15% greater reduction in LDL levels and a 15% greater improvement in dietary intake in the experimental group than the control group, it was determined this sample size (a=0.05) would have a power of 80 (b=0.20). The subjects gave informed consent to participate in this randomized trial, signed consent forms, and received free monthly classes over the course of 1 year. There was no monetary compensation for their participation. The Human Subjects Committee of the Center for Health Studies and the University of Washington Research Committee approved this project.