The prevalence of metabolic syndrome and metabolically healthy obesity in Europe: a collaborative analysis of ten large cohort studies

Abstract

Background: Not all obese subjects have an adverse metabolic profile predisposing them to developing type 2 diabetes or cardiovascular disease. The BioSHaRE-EU Healthy Obese Project aims to gain insights into the consequences of (healthy) obesity using data on risk factors and phenotypes across several large-scale cohort studies. Aim of this study was to describe the prevalence of obesity, metabolic syndrome (MetS) and metabolically healthy obesity (MHO) in ten participating studies.

Methods: Ten different cohorts in seven countries were combined, using data transformed into a harmonized format. All participants were of European origin, with age 18-80 years. They had participated in a clinical examination for anthropometric and blood pressure measurements. Blood samples had been drawn for analysis of lipids and glucose. Presence of MetS was assessed in those with obesity (BMI ≥ 30 kg/m2) based on the 2001 NCEP ATP III criteria, as well as an adapted set of less strict criteria. MHO was defined as obesity, having none of the MetS components, and no previous diagnosis of cardiovascular disease.

Results: Data for 163,517 individuals were available; 17% were obese (11,465 men and 16,612 women). The prevalence of obesity varied from 11.6% in the Italian CHRIS cohort to 26.3% in the German KORA cohort. The age-standardized percentage of obese subjects with MetS ranged in women from 24% in CHRIS to 65% in the Finnish Health2000 cohort, and in men from 43% in CHRIS to 78% in the Finnish DILGOM cohort, with elevated blood pressure the most frequently occurring factor contributing to the prevalence of the metabolic syndrome. The age-standardized prevalence of MHO varied in women from 7% in Health2000 to 28% in NCDS, and in men from 2% in DILGOM to 19% in CHRIS. MHO was more prevalent in women than in men, and decreased with age in both sexes.

Conclusions: Through a rigorous harmonization process, the BioSHaRE-EU consortium was able to compare key characteristics defining the metabolically healthy obese phenotype across ten cohort studies. There is considerable variability in the prevalence of healthy obesity across the different European populations studied, even when unified criteria were used to classify this phenotype.

Figure 1

The prevalence of obesity in the participating cohorts given as a percentage of the total sample size of the cohort.

Figure 2

The frequency of individual components of the metabolic syndrome among obese subjects (BMI ≥ 30 kg/m²). The presence of the metabolic syndrome mainly depends on the presence of a high blood pressure followed by the level of triglycerides and HDL cholesterol and – to a lesser extent – blood glucose levels. BP = blood pressure, BG = blood glucose, HDL-C = high density lipoprotein cholesterol, TG = triglycerides. *Denotes non-fasting measurement of blood glucose.

Figure 3

Age-standardized prevalence of metabolic syndrome (MetS) and metabolically healthy obesity (MHO) amongst obese (BMI ≥ 30 kg/m ² ) individuals in the participating cohorts, separately shown for men (panel A, left) and women (panel B, right).

Figure 4

Percentage of subjects (panel A: men; panel B: women) meeting the criteria of being ‘healthy obese’. The results are stratified for different age groups. In general, within each cohort the prevalence of healthy obesity decreases with increasing age. Note that more females are metabolically healthier than males.