Metabolic Syndrome

The World Health Organization (WHO) defines Metabolic Syndrome as:

The WHO publication that defines metabolic syndrome describes epidemiological studies that have shown that the syndrome occurs relatively commonly in a wide variety of ethnic groups, including Europeans and Afro/Mexican Americans. However, the actual frequency with which the metabolic syndrome occurs is difficult to define exactly, since this depends on the initial definition of what constitutes an abnormality. Not all of the publications on the prevalence of the syndrome have used the WHO criteria to define their patient population.

A population based study performed in Europe showed that 20-25% of the population exhibit at least two of the metabolic abnormalities associated with metabolic syndrome. A blood pressure value greater than or equal to 140/90 mmHg was also defined as an abnormality. Although the criteria used to define abnormality in this study were more conservative than the WHO definition, and therefore would have resulted in a higher percentage of patients being defined as having an abnormality, the model of the syndrome described in the publication is still generally applicable. The publication also describes other, more stringent, definitions set by expert panels of clinicians and discusses the effects of using these criteria on the population studied.

As stated in the WHO publication, each component of the metabolic syndrome alone conveys increased cardiovascular risk, but as a combination they become much more powerful. The study by Trevisan et al showed an estimated increase in hazard ratio for all cause mortality of between 1.95 (males) and 2.54 (females) times that of normal. If deaths caused by cardiovascular disease or coronary heart disease are considered, the increased risk is even more striking (with risk factors of approximately 3 in males and 16 in females).

Another study conducted in Finland has examined the mortality rates of 133 middle aged subjects, who were newly diagnosed with Type 2 diabetes and compared them with the mortality rates in 144 control subjects. Patients were followed for 15 years. The results showed that total mortality was markedly higher in patients with Type 2 diabetes compared to controls (44.3% vs 12.9% in males and 44.4% vs 11.0% in females). This translates to an age-adjusted odds ratio of 5.0 for males and 5.2 for females. The odds ratios were higher if cardiovascular mortality only was considered (being 6.2 and 11.2 for males and females respectively). This study also showed a strong link between lipoprotein abnormalities and cardiovascular mortality.

Whatever the actual prevalence, all available data point to an incidence for the severe form of the syndrome that is still high enough to present a considerable public health problem.