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EDITORS

Rosemarie Perrin, Editor; Camille Martin, Editor, Preventing Chronic Disease. Disclosure: Rosemarie Perrin and Camille Martin have disclosed no relevant financial relationships.

CME AUTHOR

Laurie Barclay, MD. Freelance writer and reviewer, Medscape, LLC. Disclosure: Laurie Barclay, MD, has disclosed no relevant financial relationships.

AUTHORS AND CREDENTIALS

Disclosures: Brian Armour, PhD; Elizabeth Courtney-Long, MA, MSPH; Vince Campbell, PhD; Holly R. Wethington, PhD have disclosed no relevant financial relationships.

Affiliations: Brian Armour, Division of Human Development and Disability, Centers for Disease Control and Prevention, Atlanta, Georgia; Elizabeth Courtney-Long, Vince Campbell, Holly R. Wethington, Centers for Disease Control and Prevention, Atlanta, Georgia.

We obtained the data for this study from the 2003–2009 NHIS, a nationally representative, in-person, household survey of the civilian, noninstitutionalized US population that is conducted by the National Center for Health Statistics. The survey collects comprehensive demographic, health, behavioral risk, preventive health, and disability data. The NHIS data are used to examine trends in health and disability and to assess progress in meeting national health objectives (eg, Healthy People 2020).

The NHIS core consists of 4 major components: household, family, sample child, and sample adult. The household component collects demographic information on all household residents. The family component collects additional demographic information on each household family member, as well as data on health status, limitations, injuries, health care access and use, health insurance, and income and assets. For each family, 1 adult and 1 child are randomly selected, and more detailed information on specific conditions and health behaviors is collected. Our study used data from the 2003–2009 sample adult, family, and household questionnaires. NHIS complies with Department of Health and Human Services regulations (45 CFR 46) for protection of human subjects (http://www.cdc.gov/nchs/nhis.htm).

We used responses to 2 questions from the 2003–2009 NHIS questionnaires to determine BMI: “How tall are you without shoes?” and “How much do you weigh without shoes?” We used the NHIS definitions to categorize adults as underweight (BMI <18.5), normal weight (BMI, 18.5-24.9), overweight (BMI, 25−29.9), or obese (BMI ≥30) (1).

Disability is a complex, multidimensional experience characterized by the interaction of an impairment (eg, spinal cord injury) with environmental factors (eg, lack of sidewalks) that may produce varying degrees of limitation in a person’s activities or participation in social activities (5,6,10,11). Disability is defined differently among surveys, depending on several factors, including, for example, the conceptual model of disability the survey designer uses (12). The NHIS includes many questions relating to structural and functional impairments and activity limitations, enabling investigators to achieve greater detail in defining disability. The Nagi model of disability considers the causes of disability to be multidimensional and to include individual attributes and environment (13). The Nagi model was a cornerstone of the 1991 Institute of Medicine report on disability (5), which was published the year following passage of the Americans with Disabilities Act (ADA) (14). The ADA defines disability as a physical or mental impairment that substantially limits 1 or more major life activities (14). Consistent with the ADA definition of disability, the NHIS questions were used to construct 2 disability subcategories: basic actions difficulty and complex activity limitation (10).

Basic actions are essential functions that enable a person to maintain independence and participate in social activities (10). Basic actions difficulties include movement, emotional, sensory, and cognitive difficulties. Complex activity limitations are complications experienced in performing tasks or engaging in social actions (5,10). The components of complex activity limitation include social and work limitations, as well as limitations with self-care activities of daily living (ADL) or instrumental activities of daily living (IADL). NHIS used several questions to define the components of basic actions difficulty and complex activity limitation. Respondents who were identified as having a basic actions difficulty or complex activity limitation were classified as having any limitation. These disability subcategories and their various components were used both separately and collectively to assess the association between BMI category and disability.

We used SAS-callable SUDAAN, version 10.0.1 (Research Triangle Institute, Research Triangle Park, North Carolina) to obtain national estimates of disability, type of disability, and obesity prevalence. We obtained prevalence estimates of sociodemographic variables to examine the population distribution of obese adults compared with those who are not obese. We examined the following variables: sex, age group (18–44 y, 45–64 y, and ≥65 y), race/ethnicity (Hispanic, non-Hispanic white, non-Hispanic black, non-Hispanic of another race ), education level (less than a high school education, high school graduate, associate or technical degree, college graduate), employment status (employed, unemployed, retired/student/homemaker, unable to work), annual household income (<$35,000, $35,000–$74,999, ≥$75,000), marital status (married, living with partner, widowed, divorced/separated, never married), and region of the country. We combined data from multiple years to ensure that stable estimates were calculated for the various types of disability. Because adjusted measures of obesity have not shown significant change from 2003 to 2010 (1), the survey years of 2003 through 2009 were combined. A total of 190,786 respondents completed the sample adult questionnaire from 2003 through 2009, yielding an aggregate final sample adult response rate of 69.0% (the individual year final sample adult response rates ranged from 62.6% to 74.2%). A total of 178,999 respondents were included in our overall analysis. For each of the BMI categories, our total sample sizes were underweight (n = 3,182); normal weight (n = 66,698); overweight (n = 63,510); and obese (n = 45,609). Respondents were excluded from the entire analysis if their BMI information was missing (n = 8,645), if they had an extreme BMI value (<15 or >50 [ n = 1,173]), or if they were pregnant (n = 2,092). Exclusions were not mutually exclusive, so there was some overlap among categories. Data were weighted to account for differential probability of selection and to adjust for nonresponse. Estimates were age-adjusted to the 2000 US standard population (15) to account for the higher prevalence of disability in older age groups (10). We conducted t tests to compare the prevalence of disability in the weight status categories of underweight, overweight, and obese to prevalence in the normal-weight category for each disability type, by sex.

Overall, 31.2% of adults self-reported a disability, approximately 27.0% of normal-weight adults and 41.0% of obese adults (any limitation). Among men, 26.7% of those at a normal weight had a disability compared with 35.2% of those who were obese (Table 3). Among women, 26.8% of those at a normal weight had a disability compared with 46.9% of those who were obese (Table 4). Underweight men and women were more likely to have a disability (any limitation) than those of normal weight (Tables 3 and 4).

Among men, 24.1% of those at a normal weight reported having a basic-actions difficulty compared with 32.9% of those who were obese. Among women, 25.1% of those at a normal weight had a basic-actions difficulty compared with 45.0% of those who were obese. Movement difficulty was the most common type of basic-actions difficulty, affecting 15.5% of normal-weight men, 25.3% of obese men, 17.6% of normal-weight women, and 37.9% of obese women. Emotional difficulty was the least common type of basic-actions difficulty that normal-weight men and women reported (2.1% and 2.6%, respectively). In contrast, cognitive difficulties were the least common disability among obese men, affecting 2.9%, and hearing difficulties were the least common disability among obese women, affecting 3.6%.

The prevalence of movement difficulty was approximately 1.5 times higher for obese men in comparison to normal-weight men (15.5% vs 25.3%; P < .001). Similarly, the prevalence of movement difficulty was twice as high for obese women as for normal-weight women (17.6% vs 37.9%; P < .001).

Underweight men were more likely than normal-weight men to experience basic-actions difficulty (39.7% vs 24.1%, P ,<.001) as were underweight women (31.2% vs 25.1%, P ≤ .001). Underweight men had a significantly higher prevalence of disability across all types of basic action difficulty than normal-weight men, with the exception of hearing difficulty, which was similar for both groups. Underweight women had a significantly higher prevalence of all basic-actions difficulties than normal-weight women.

Among men, 13.4% of those at a normal weight reported having a complex-activity limitation compared with 16.7% of those who were obese. Among women, 11.6% of those at a normal weight reported having a complex-activity limitation compared with 23.0% of those who were obese. Work limitation was the most common type of complex-activity limitation, affecting 11.3% and 8.9% of normal-weight men and women, respectively. It was the most common type of complex-activity limitation affecting obese adults. ADL limitation was the least common type of complex-activity limitation, affecting 1.8% and 1.7% of normal-weight men and women and 1.7% and 2.9% of obese men and women, respectively.

Underweight men were more likely than normal-weight men to experience complex-activity limitations (28.2% vs 13.4%, P ≤ .001) as were underweight women (19.4% vs 11.6%, P ≤ .001). Underweight men and men had significantly higher prevalence of complex-activity limitations than their normal-weight counterparts. (Tables 3 and 4).