Impact of age and gender on the prevalence and prognostic importance of the metabolic syndrome and its components in Europeans. The MORGAM Prospective Cohort Project

Abstract

Objective: To investigate the influence of age and gender on the prevalence and cardiovascular disease (CVD) risk in Europeans presenting with the Metabolic Syndrome (MetS).

Methods: Using 36 cohorts from the MORGAM-Project with baseline between 1982-1997, 69094 men and women aged 19-78 years, without known CVD, were included. During 12.2 years of follow-up, 3.7%/2.1% of men/women died due to CVD. The corresponding percentages for fatal and nonfatal coronary heart disease (CHD) and stroke were 8.3/3.8 and 3.1/2.5.

Results: The prevalence of MetS, according to modified definitions of the International Diabetes Federation (IDF) and the revised National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATPIII), increased across age groups for both genders (P<0.0001); with a 5-fold increase in women from ages 19-39 years to 60-78 years (7.4%/7.6% to 35.4%/37.6% for IDF/NCEP-ATPIII) and a 2-fold increase in men (5.3%/10.5% to 11.5%/21.8%). Using multivariate-adjusted Cox regressions, the associations between MetS and all three CVD events were significant (P<0.0001). For IDF/NCEP-ATPIII in men and women, hazard ratio (HR) for CHD was 1.60/1.62 and 1.93/2.03, for CVD mortality 1.73/1.65 and 1.77/2.06, and for stroke 1.51/1.53 and 1.58/1.77. Whereas in men the HRs for CVD events were independent of age (MetS*age, P>0.05), in women the HRs for CHD declined with age (HRs 3.23/3.98 to 1.55/1.56; MetS*age, P=0.01/P=0.001 for IDF/NCEP-ATPIII) while the HRs for stroke tended to increase (HRs 1.31/1.25 to 1.55/1.83; MetS*age, P>0.05).

Conclusion: In Europeans, both age and gender influenced the prevalence of MetS and its prognostic significance. The present results emphasise the importance of being critical of MetS in its current form as a marker of CVD especially in women, and advocate for a redefinition of MetS taking into account age especially in women.

Figure 1. Frequency of each MetS component according to gender and age group.

MetS indicates the metabolic syndrome; IDF, the International Diabetes Federation; and ATPIII, Adult Treatment Panel III. The men/women ratio is 38639/30455 for all components except for waist circumference (men/women  = 23817/152899) since not all cohorts registered waist circumference. P<0.0001 for each MetS component across age groups in men and women separately. Gender differences within each age group, with P<0.0001^a, P<0.01^b, P<0.05^c, NS indicates non-significance, P>0.05, and the dashed line indicates the same level of significance across the age groups.

Figure 2. Frequency of MetS according to gender and age group.

MetS indicates the metabolic syndrome; IDF, the International Diabetes Federation (MetS IDF) criteria and the National Cholesterol Education Program–Adult Treatment Panel III (MetS ATP) criteria. Numbers above each bar indicate total number of persons with MetS/total number of persons in the given age group; All P<0.0001 for each of the 4 MetS/gender combination across age groups. Within each age group, P<0.0001 between genders, except for MetS ATP in ages 40–49 years (P = 0.57).

Figure 3. Age- and gender-specific incidence rates per 1000 person years for CVD with increasing number of risk factors.

Risk factors refer to the components of the metabolic syndrome (MetS); and CVD, cardiovascular disease: (A) fatal and nonfatal CHD, (B) fatal and nonfatal stroke, and (C) cardiovascular death. Numbers above each bar indicate event/person. Overall trend with P<0.0001 for incidence rates with increasing number of MetS risk factors and age categories at baseline. Within each age group, the reported P values indicate significant differences in incidence rates with rising number of MetS risk factors, except in men (for CVD) and women (for stroke and CVD) below age 40 years.

Figure 4. Age- and gender-specific incidence rates per 1000 person years for CVD with or without the presence of MetS.

MetS IDF indicates the metabolic syndrome defined according to the International Diabetes Federation criteria; MetS ATP, the metabolic syndrome defined according to the National Cholesterol Eduation Program-Adult Treatment Panel III; and CVD, cardiovascular disease: (A) fatal and nonfatal CHD, (B) fatal and nonfatal stroke, and (C) cardiovascular death. Numbers above each bar indicate events/persons. Comparison of incidence rates between men and women with MetS within each age group using Pearson Chi²-test, P<0.05^a, P<0.0001^b, and NS indicates non-significance, P>0.05.