Early screening for metabolic syndrome opens a window of opportunity - learnings from a long-term, population-based study
Authors: Loennberg L , Rehn M , Leppert J , Ohrvik J , Chabok A , Damberg M 
Published: November 2023

Abstract

Introduction
The metabolic syndrome (MetS) represents a cluster of risk factors that predict cardiovascular disease (CVD) and type 2 diabetes. Early detection of MetS opens up for a successful treatment of the cardiovascular (CV) risk factors involved, hopefully leading to later advent of CVD in the general population.

Purpose
In this long-term, population-based study we aimed to investigate how presence of MetS, in middle-aged men and women, was associated with all-cause mortality and non-fatal CVD later in life.

Methods
Between 1990 -1999 a screening program was conducted among 40- and 50-year-old inhabitants in the County of Västmanland, Sweden. Data on lifestyle habits and socio-economic status were collected. Total cholesterol, fasting blood glucose, blood pressure, weight, height, waist and hip circumference were measured. Individuals that met three or more of the following risk factors were classified with MetS: waist circumference: ≥102 cm (men) and ≥88 cm (women), total cholesterol: ≥6.1 mmol/ l, blood pressure: ≥130 and/ or ≥85 mm Hg (or previous diagnosis of hypertension) or fasting plasma glucose: ≥5.6 mmol/ l (or previous diagnosis of type 2 diabetes). A control group was identified with individuals from the same population, without MetS diagnosis. Each participant with MetS was matched to two controls regarding sex, age and date for the health examination. The association between midlife MetS and all-cause mortality and non-fatal CV events (stroke and myocardial infarction) was adjusted for age, sex, smoking, physical inactivity, educational level, BMI, hip circumference and living alone or with family members. Multivariable cox regression and Kaplan-Meier analyses were used.

Results
A total number of 5084 individuals met the criteria for MetS and a control group of 10 168 individuals was identified. The median (Q1, Q3) follow-up time was 27 years (24.6, 30.1), corresponding to 130 820 and 269 696 person-years at risk in the MetS and the control group respectively. During follow up, 1317 MetS and 1904 control subjects died, implying 10 deaths in the MetS group and 7 deaths in the controls per 1000 person-years at risk (fig. 1). Cox analysis showed increased mortality in the MetS group compared to the controls, hazard ratio (HR) 1.30 (95% CI: 1.20-1.40); p&lt;0.001. Non-fatal CV events in the MetS group and in the controls were 32.4% vs 22.8%, respectively (p&lt;0.001); HR 1.35 (CI;1.25–1.46) (fig 2). Median time (Q1, Q3) for first non-fatal CV event was 16.8 years (9.9,22.3) in the MetS group and 19.1 (12.2, 23.6) for the controls.

Conclusions
Results from this long-term, population-based study underline that the risk of non-fatal CVD and all-cause mortality was significantly higher in individuals with asymptomatic MetS. Present results support previous studies that early identification of MetS with screening programs might open a window of opportunity for prevention of CVD and premature death in the general population.Figure 1.All-cause mortalityFigure 1.Cardiovascular events