Analysis of baseline data from 161,393 older women participating in the WHI demonstrated that the odds of poor physical HRQOL increased as weight category increased in diverse racial/ethnic groups. Self-rated health showed the largest proportional change in physical HRQOL across clinical weight categories. The odds of poor physical HRQOL among women with class 3 (or extreme) obesity were substantially higher than were those among normal weight women. AA and AI/AN women had the highest prevalence of obesity and extreme obesity. However, the greatest change in adjusted odds of poor physical HRQOL was between extremely obese women and those of lower weight categories, suggesting that extreme obesity carries a particularly high burden in terms of physical HRQOL. In addition, the results confirm that extremely obese AA and H/L women with lower educational levels had even greater risk of poor physical HRQOL. Some studies support the notion that those with excess weight conditions are likely to have lower educational levels.23,34,35
In the context of obesity and HRQOL, a cross-sectional study found that women with lower educational level were at least 76% more likely to have lower scores in the domains of physical functioning and general health.34
These findings suggest that although morbidity risk increases with the transitions from normal weight to overweight to obese, those with extreme obesity demonstrate the greatest risk. This is particularly true for that subset of minority women who are also poorly educated. This group deserves more attention, as the steepest incline of obesity rates has occurred for the heaviest weight categories in the U.S. population.37
It is important to delineate the impact of physical health and psychosocial factors on various outcomes with obesity; the relative importance that each contributes to obesity-associated physical HRQOL in women needs to be established. A recent cross-sectional study found that increasing age was associated with greater impairment in physical domains (physical functioning, work, sexual life) of weight-related QOL but lesser impairment in psychosocial domains (public distress, self-esteem).15
Likewise, one prospective study of weight change and HRQOL demonstrated a stronger connection between weight and physical health factors (e.g., physical functioning, bodily pain, vitality) than between weight and mental health factors (anxiety, depression, emotional problems, and psychological well-being) in obese women.6
Another examined gender differences in the association among obesity, mood disorders, and emotional well-being, with a stronger association between obesity and mental health in women than in men,17
suggesting that weight stigmatization is more likely to upset emotional health among obese women than obese men. This analysis examined emotional/psychological factors with potentially positive and potentially negative effects to discover that there appears to be a lesser impact of emotional/psychological factors (vs. physical health factors) on physical HRQOL. Previous research has demonstrated the importance of emotional states on physical health and how positive feeling states promote good health behaviors and a more favorable outlook.20
An important follow-up would be to examine mental HRQOL for probable racial/ethnic differences in how stigma or stress and social support are perceived.
Additionally, this analysis showed that as the weight category increased, women were more likely to report having at least one chronic medical condition, having lower self-rated health, or having moderate to severe pain. It also showed that of all the physical health factors measured, self-rated health was the strongest predictor of poor physical HRQOL. These findings support earlier research showing the following: (1) obesity-related comorbid diseases are prevalent across diverse racial/ethnic groups and adversely impact physical HRQOL, particularly as it relates to CHD, diabetes, osteoarthritis, and respiratory disorders,3,9,10,50
(2) people with higher BMIs report greater impairment of HRQOL31,33
and have a poorer perception of their health status,8
and (3) the presence of pain represents a significant covariate of obesity and has an independent effect on HRQOL.51
These results show that physical health factors exert a greater negative influence on physical HRQOL than do emotional/psychological characteristics and do so to a similar degree across diverse racial/ethnic cohorts. Accordingly, these findings would support the adverse impact of obesity on disability. A recent study examined self-reported functional impairment among older persons over a 16-year period.52
Findings demonstrated that obese persons had a 43% increased risk of functional impairment over time.52
Disability is greatest among obese older women.52,53
The associated reduction in HRQOL is probably mediated through lower activity states or possibly through fears related to loss of independence; the role of sedentary behavior in the association between obesity and poor HRQOL should be explored in future analyses. In the analyses presented here, however, accounting for the major weight-related physical health variables, considerable risk of poor physical HRQOL remained, suggesting an independent effect of obesity or absence of an important covariate, such as functional status, severity of comorbid conditions, and self-care ability.
The WHI is one of the first large studies to examine physical and emotional/psychological factors simultaneously in the context of BMI's impact on physical HRQOL. In addition, this study has a very large, racially/ethnically diverse sample from 40 U.S. clinical sites, which allows the unique opportunity to provide more accurate comparisons across these varied groups. However, it does have some limitations. First, the emotional/psychological health factors assessed in the WHI do not collectively comprise a standardized measure and may lack the statistical strength to detect an effect between weight and physical HRQOL. However, each factor was adopted from a validated measure. Second, a large portion of the residual effect that was found in the fully adjusted model may be accounted for by factors not measured in this study, including mobility limitations and mental HRQOL. Third, many variables used in this analysis were self-reported data, which has response bias as an inherent limitation. Although self-rated health had a positive correlation with the PHC score, evidence has demonstrated that these two constructs are distinctly different. In a meta-analysis of health status and QOL,54
it was determined that although self-rated health correlated with HRQOL, mental health has the greater impact on HRQOL and physical functioning has a greater impact on self-rated health from the patient's perspective. Finally, the cross-sectional nature of this study limits any causal inferences about the results. Although the trend of weight change was not examined, it is likely important in explaining the association between BMI and physical HRQOL. Furthermore, smaller proportions of racial/ethnic minority groups and the higher socioeconomic status (more educational attainment and a high proportion of insured) of this sample compared with the general population limit the generalizability of the results; however, the large numbers within these groups strengthen the detected effects of weight on physical HRQOL.