Obesity Matters : Findings in the Utrecht Health Project and the Framingham Heart Study

Abstract

Studies in this thesis focused on the burden and treatment of overweight, obesity and their associated co-morbidities in the general adult population. Overweight and obesity have reached epidemic proportions globally. Overweight and obesity are defined as abnormal or excessive fat accumulation that may impair health. The body mass index (BMI=kg/m2) is a useful measure of excess body weight at a population level. A BMI of 25 or over is defined as overweight, with a BMI between 25 and 30 classified as moderate overweight and a BMI?30 as severe overweight or obesity. For our studies we predominantly used data from two large ongoing population-based prospective cohort studies, the Utrecht Health Project (or in Dutch “Leidsche Rijn Gezondheidsproject”) and the Framingham Heart Study. We compared the prevalence of physical and mental health conditions, and health-related quality of life among individuals with normal weight, moderate overweight and obesity upon entering a new primary care practice. Overweight was associated with a broad range of physical and mental health conditions and a reduced health-related quality of life. Measurement of BMI, as part of a health assessment at intake in a primary care practice may be an easy procedure to start being informed on many health risks. In addition, we assessed the rates of treatment and control of CVD risk factors among individuals in different BMI categories. Despite the higher burden of CVD risk factors among individuals with obesity than those without, rates of treatment and control of CVD risk factors were suboptimal. This suggests it may be more difficult to achieve treatment goals with standard therapy among obese individuals. Therefore we examined the influence of BMI on the impact of intensive versus standard lipid-lowering statin therapy on cardiovascular outcomes in patients with acute coronary syndrome. Among overweight patients, intensive therapy resulted in a lower risk of cardiovascular complications, whereas no increased clinical benefit was apparent among normal weight patients. As abdominal adiposity -in particular visceral adipose tissue (VAT)- is strongly associated with cardiometabolic risk, we investigated the relation between lifestyle factors and subcutaneous abdominal adiposity (SAT) and VAT. A healthy diet and physical activity were associated with lower SAT and VAT, whereas smoking and high alcohol intake were differentially associated with higher VAT. Most trials involving lifestyle interventions for the management of overweight are performed in academic medical centers. To evaluate the efficacy of a multidisciplinary weight management program for overweight adults in routine primary care we conducted a randomized trial. The results from this trial suggest that exercise counseling does not significantly add to the beneficial effect of nutritional counseling on body weight, but may have a small additional beneficial effect on waist circumference. In the last study we demonstrate that the use of self-reported data to estimate the prevalence of hypertension and diabetes may lead to underestimated prevalence estimates and biased associations with risk factors. Adding biometrical measurements may increase the validity of the data. We close the thesis by reflecting on certain methodological aspects of the use of routine health care data for epidemiologic and public health research.