The Metabolic Syndrome-the "Syndrome X Factor"-at Work
Nico Pronk, Ph.D., FACSM, FAWHP, is vice president of Health & Disease Management at HealthPartners health system in Minneapolis, Minnesota, with responsibility for health promotion, disease prevention and disease management programs for the health plan membership. He also is the executive director of the Health Behavior Group, a HealthPartners business unit that provides health promotion, disease prevention and disease self-management products and services to the local, national, and international wellness market. As a senior research investigator at the HealthPartners Research Foundation, he conducts studies in the areas of behavior change, population health improvement and the impact of systems-level change on health-related outcomes. Dr. Pronk has published extensively in the areas of exercise and physical activity, behavior change, economic impact of health risk factors, and the integration of health risk management strategies in population health initiatives. He is currently an associate editor for ACSM's Health & Fitness Journal®, a member of the International editorial board of Disease Management & Health Outcomes, and an editorial board member of the CDC e-journal Preventing Chronic Disease. He is a current member of the Task Force on Community Preventive Services and the Clinical Obesity Research Panel (CORP) at the National Institutes of Health. Dr. Pronk received Fellow status for ACSM and the former Association for Worksite Health Promotion (AWHP).
The metabolic syndrome, formerly called syndrome X, represents a cluster of health risk factors present at one time in a given individual. This clustering of multiple interrelated risk factors dramatically raises overall risk for an individual to develop conditions such as diabetes, cardiovascular disease, or even premature death. Information regarding the clustering of multiple behavioral health risks has been discussed (1, 2). For the metabolic syndrome, however, the clustering is not characterized around health behaviors but rather around modifiable health risk factors including obesity, blood lipids, blood pressure, and insulin resistance (3).
So, What Really IS the Metabolic Syndrome?
The term "metabolic syndrome" has been widely accepted in the medical scientific literature-although several varying definitions exist-and it even has its own International Classification of Diseases code (277.7). The Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III or ATP III) (4) definition is used in the United States and is the one most likely used for clinical purposes. Several definitions of the metabolic syndrome are provided in the table below.
Prevalence in the United States
Multiple risks cluster quite frequently within individuals. From a behavioral risk factor perspective, 57.7% (i.e., the majority) of the U.S. adult population meets the definition of having multiple (≥2) risk factors of only four health behaviors (smoking, physical inactivity, overweight, and risky drinking) (2). The prevalence of the metabolic syndrome among U.S. adults 20 years and older has been estimated to be 23.7% (7). Wide variation occurs around age and race, but not between men and women. For example, prevalence for men is 24.0%, and for women, it is 23.4%. On the other hand, for those aged 20 to 29 years, prevalence was 6.7% compared with 43.5% for those aged 60 to 69 years. Prevalence was highest among Mexican Americans (31.9%) and lowest among African Americans (21.6%).
Prevalence in the Worksite Setting
Knowing that age is directly related to prevalence of the metabolic syndrome may lead to the assumption that most of the health concerns related to this will occur in the older population and retirees. Unfortunately, this is not true. The metabolic syndrome occurs in 23.1% of the U.S. work force compared with the 23.7% noted above for the entire U.S. adult population. Prevalence is approximately the same in both sexes but varies greatly across weight categories. Figure 1 shows the impact of weight (body mass index) across three age strata for employees based on data from the National Health and Nutrition Examination Survey 1999 to 2000 (8). Whereas the average prevalence is 23.1%, the prevalence among obese workers is as high as approximately 50% to 70% among 20- to 39-year-olds and 60-year-olds or older, respectively. Hence, the metabolic syndrome affects a large proportion of the work force, places those affected at elevated risk for major diseases and disorders, and disproportionately affects those who are overweight and obese.
What Can Be Done?
Is there any indication that strategies designed to lower the disease risk for those affected with metabolic syndrome are effective? If so, are there valid and affordable ways in which employees with metabolic syndrome can be identified? What if diagnosis of metabolic syndrome is too cumbersome-can anything be done to ameliorate the potential impact of this condition without formal diagnosis?
In the worksite setting, on-site screening approaches represent tactics to identify employees with metabolic syndrome. However, whereas waist circumference, triglycerides, HDL, and blood pressure may be relatively easy to measure, measurement of fasting glucose is more difficult because the employee needs to be in a fasted state. Identification of the condition based on claims analysis is problematic; hypertension has a high false-positive rate; previously diagnosed hypertension or hyperlipidemia may be currently under control, and obesity codes are underreported. Furthermore, the diagnoses codes coming from the claims data may indicate the presence of the condition, but do not provide insight into the severity of the condition. So, there are some concerns about a systematic method by which to identify potential program candidates.
The Diabetes Prevention Program (DPP) was a large randomized controlled trial designed to study the impact of lifestyle and pharmacological intervention on the prevention of diabetes among subjects with impaired glucose tolerance (9). After 3.2 years of follow-up, the lifestyle intervention (which consisted of an intensive lifestyle regimen designed to induce 7% weight loss and 150 minutes of exercise per week) was effective at preventing or delaying the onset of diabetes for 58% of the subjects compared with 31% among those subjects who treated with Metformin®. Many of the DPP subjects actually met the criteria for metabolic syndrome, and therefore, this study also served as a data source for the impact of lifestyle and drug intervention on metabolic syndrome (10). Using the ATP III criteria (outlined above), 53% of the study population was identified with metabolic syndrome. The proportion of subjects who met the criteria for the individual components of the metabolic syndrome showed the following prevalence:
* waist circumference, 78%
* high triglyceride level, 57%
* low HDL cholesterol, 46%
* high blood pressure, 45%
* fasting blood glucose, 33%
The results of the intervention were very encouraging and are depicted in Figure 2. The prevalence of metabolic syndrome was significantly reduced from 51% to 43% in the intensive lifestyle intervention group. An impressive result, especially when considering that, during the course of the study, the prevalence actually increased among the control subjects from 55% to 61%. In the Metformin® group, the results remained unchanged. The change in prevalence among members of the lifestyle intervention group amounts to a 41% reduction relative to the control group and a 29% reduction compared with the Metformin® group. Hence, the impact of a moderate amount of weight loss and an increase in physical activity is not only effective in reducing the incidence in diabetes, but also is more effective in reducing other components of the metabolic syndrome.
Recommendations for Addressing Metabolic Syndrome at the Worksite
The findings that obesity and waist circumference are highly prevalent among those with metabolic syndrome! and that weight loss and increased physical activity are effective interventions present a solution for addressing this condition at the worksite. Even if diagnosis of the conditions is problematic, providing employees who meet the obesity and low physical activity criteria access to intervention opportunities is a first step. Next, those who are at elevated levels of risk based on their own self-report of high blood pressure, high cholesterol, an expanded waist line, or even family history of diabetes can be encouraged to visit their physician and check their blood lipids and glucose. The traditional approaches to increasing awareness of the risk factors, providing access to effective behavior change programs, and identifying and creating a supportive work environment and social support system remain cornerstone strategies to implementation of programs that generate impact. However, while some of the interventions can occur at the worksite, some risk factors should be addressed in collaboration with the health care system. Employees should be encouraged to seek appropriate care from their physician. A summary of recommended steps in the treatment of metabolic syndrome includes the following:
* behavioral therapy for the reduction of obesity and increase in physical activity
* treatment of existing chronic disease risk factors for diabetes, cardiovascular disease, renal disease, peripheral vascular disease, and stroke
While medical treatment for the risk factors is important, employees should be made aware that, based on the evidence, the behavioral intervention (i.e., weight loss and physical activity) in the DPP trial was more effective than the pharmacological agent Metformin® for improvements in HDL cholesterol, triglycerides, and blood pressure.
The metabolic syndrome represents a major modifiable risk factor cluster highly prevalent among employees that can be effectively addressed with lifestyle interventions. Moderate weight loss and increased physical activity are highly effective strategies that can reduce the number of employees who are at elevated risk for disease or premature death. Worksite health promotion practitioners are highly qualified and prepared to implement such strategies at the worksite.
1. Pronk, N.P., C.J., Peek, and M.G. Goldstein. Addressing multiple behavioral risk factors in primary care. American Journal of Preventive Medicine
2. Pronk, N.P. Addressing multiple risk factors at the worksite: birds of a feather flock together. ACSM's Health & Fitness Journal
® 8:28-31, September/October 5, 2004.
3. Shen, B.J., J.F., Todaro, R. Niaura, et al. Are metabolic risk factors one unified syndrome? Modeling the structure of the metabolic syndrome X. American Journal of Epidemiology
4. National Institutes of Health. Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III). Bethesda, MD: National Institutes of Health, 2001. NIH Publication 01-3670.
5. World Health Organization. Definition, Diagnosis, and Classification of Diabetes Mellitus and Its Complications: Report of a WHO Consultation, Geneva: World Health Organization, 1999.
6. International Diabetes Federation. The IDF consensus worldwide definition of the metabolic syndrome. Available at www.idf.org
. Accessed March 28, 2006.
7. Ford, E.S., Giles, W.H., Dietz, W.H. Prevalence of the metabolic syndrome among US adults. The Journal of the American Medical Association
8. Hertz, R.P., A.N., Unger, M. McDonald, et al. The impact of obesity on work limitations and cardiovascular risk factors in the U.S. workforce. Journal of Occupational and Environmental Medicine
9. Knowler, W.C., E., Barrett-Connor, S.E., Fowler, et al. Diabetes Prevention Research Group. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. New England Journal of Medicine
10. Orchard, T.J., M., Temprosa, R., Goldberg, et al. Diabetes Prevention Research Group. The effect of metformin and intensive lifestyle intervention on the metabolic syndrome: The Diabetes Prevention Program. Annals of Internal Medicine