Obesity Epidemiology

OBESITY AND HEALTH-RELATED QUALITY OF LIFE 235young and middle-aged men 11 (while in a study among young women, a significantassociation between overweight/obesity and higher suicide risk was observed 12 ). Onthe other hand, many studies have also documented the social stigma associated withthe condition of being obese (e.g., references 13 and 14), which would place affectedindividuals at increased risk of low self-esteem and negative affect. Examining theimpact of obesity on generically-assessed HRQOL provides additional insight into theseapparently contradictory findings. Furthermore, most studies of “hard” health outcomesassociated with obesity (such as cardiovascular disease, diabetes, hypertension, andgallstones) provide only a narrow window through which to examine the impact ofthis risk factor on people’s lives. Although examining specific health outcomes are ofetiologic interest, they are the “tip of the iceberg” when it comes to assessing the trueextent of the population burden of morbidity associated with overweight and obesity.People care about the consequences of health risks (such as obesity) on their abilityto perform their daily activities and social roles, and studies of HRQOL thus providevaluable information for consumers, clinicians, and policy makers.Mechanisms Linking Obesity to HRQOLObesity can adversely affect HRQOL because of the symptoms and treatments associatedwith the specific diseases that it causes (e.g., pain from arthritis, functional limitations dueto cardiovascular disease). However, obesity may deleteriously affect HRQOL above andbeyond the effects that are mediated by established diagnoses. First, obesity may limita person’s ability to function even in the absence of established disease. An overweightindividual may not have been diagnosed with hypertension or diabetes, and yet reportsignificant limitations in daily activities such as walking up a flight of stairs, bendingor stooping, or carrying groceries. Second, the stigma associated with being obesemay compromise an individual’s ability to function in social settings. There is interestin documenting both the direct and indirect (i.e., mediated by established diagnoses)consequences of obesity for HRQOL.In observational studies linking obesity to HRQOL, causal inference is complicatedby the fact that health behaviors, such as sedentarism, may act simultaneously as bothconfounders and mediators of the association. In other words, lack of physical activitymay mediate the association between obesity and low HRQOL. Alternatively, a sedentarylifestyle may be a common prior cause of both weight gain as well as lower HRQOL.A similar concern applies to markers of socioeconomic status (SES). Low socioeconomicposition (e.g., low educational attainment and low income) is a well-established risk factorfor obesity as well as low HRQOL, that is, it is a potential confounder of the relationshipbetween obesity and HRQOL. On the other hand, studies have also documented thatobesity earlier in life is a predictor of subsequent social mobility, 15,16 such that lowersocioeconomic position may mediate the relationship between obesity and low HRQOL.In the systematic review of the literature in this chapter, we have noted the occasionswhen observational studies attempted to measure and control for potential confoundingvariables when describing the relationship between obesity and HRQOL.In the following sections, we provide an overview of commonly used instruments tomeasure HRQOL in adult and child and adolescent populations, and summarize how wellthese measures have performed in psychometric evaluations. In addition to presentingfindings from a systematic review of the existing epidemiologic literature on obesityand HRQOL in the section “Obesity, Weight Change, and HRQOL,” we comment onmethodological issues and knowledge gaps in these studies that should be addressed infuture investigations.