Combined dietary and exercise intervention for control of serum cholesterol in the workplace

PURPOSE: To elucidate a potential combined dietary and exercise intervention affect on cardiovascular risk reduction of the National Aeronautics and Space Administration Headquarters employees. DESIGN: A nonexperimental, longitudinal, clinical-chart review study (1987 to 1996) of an identified intervention group and a reference (not a control) group. SETTING: The study group worked in an office environment and participated in the annual medical examinations. SUBJECTS: An intervention group of 858 people with initially elevated serum cholesterol, and a reference group of 963 people randomly sampled from 10% of the study group. MEASURES: Serum cholesterol data were obtained for both groups, respectively, from pre- and postintervention and annual examinations. The reference group was adjusted by statistical exclusion of potential intervention participants. Regression equations (cholesterol vs. study years) for the unadjusted/adjusted reference groups were tested for statistical significance. INTERVENTION: An 8-week individualized, combined dietary and exercise program was instituted with annual follow-ups and was repeated where warranted. RESULTS: Only the unadjusted (but not the adjusted) reference group with initial mean total serum cholesterol levels above 200 mg/dL shows a significant 9-year decline trend and significant beta coefficient tests. An intervention effect is suggested. Mean high density lipoprotein cholesterol rose slightly in the intervention group but was maintained in the reference group. CONCLUSION: With potential design limitations, the NASA intervention program focusing on a high risk group may be associated to some degree, if not fully, with an overall cardiovascular risk profile improvement.