Prevalence of Multiple Chronic Conditions Among US Adults

Estimates From the National Health Interview Survey, 2010

Brian W. Ward, PhD; Jeannine S. Schiller, MPH

Disclosures

Prev Chronic Dis. 2013;10 

In This Article

Analysis

Data Source

The NHIS is a multipurpose health survey that represents the US civilian, noninstitutionalized population.[12,13] The NHIS is multistaged and is conducted continuously throughout each calendar year by using computer-assisted personal interviews. The survey has 3 main components: the Family Core, the Sample Adult Core, and the Sample Child Core. In the Family Core, an adult self-reports for himself or herself and as a proxy for the remainder of the family. From each family, 1 adult aged 18 years or older and 1 child (if the family includes a child) are randomly chosen for the Sample Adult Core and Sample Child Core questionnaires. The selected "sample adult" self-reports for the Sample Adult portion of the NHIS (unless a health condition requires a proxy respondent to answer for this adult).[12,13] All data for chronic conditions were taken from the Sample Adult Core, and data for sex, age, race/ethnicity, and health insurance coverage were taken from the Family Core. The 2010 NHIS Sample Adult Core contained 27,157 adults, had a conditional response rate (ie, the rate for those sample adults identified as eligible without taking into account household or family nonresponse) of 77.3%, and a final response rate of 60.8%. Descriptive estimates of select sociodemographic characteristics for the 2010 adult population are in Table 1. For the trend analysis using the NHIS for the years 2001 through 2010, the lowest Sample Adult Core sample size over the 10-year period was 21,781 (2008) and the highest was 33,326 (2001). The conditional response rate was lowest in 2008 (74.2%) and highest in 2003 (84.5%); the final response rate was lowest in 2008 (62.6%) and highest in 2002 (74.3%).

Definitions

The HHS Interagency Workgroup on MCC and Office of the Assistant Secretary for Health have generated a standardized approach to defining chronic conditions in the United States,[14] which was used as a basis to generate a measure of MCC. The 2010 NHIS included questions on 10 of the 20 chronic conditions captured by the Workgroup's definition, including whether adults had ever been told by a doctor or other health professional that they had hypertension, coronary heart disease, stroke, diabetes, cancer, arthritis, hepatitis, or emphysema; had experienced weak or failing kidneys or chronic bronchitis during the past 12 months; or currently had asthma. Presence of emphysema or chronic bronchitis was combined in this analysis to form a single condition of chronic obstructive pulmonary disease (COPD). We counted the presence of each of these 10 conditions and combined them into 3 categories: 0 to 1 condition, 2 to 3 conditions, and 4 or more conditions. We also generated estimates for the 5 most common MCC dyad and triad combinations by sex and age group, and we estimated weighted prevalences for the 5 most common combinations. Within each combination, chronic conditions are listed alphabetically. These MCC dyad and triad combinations were not mutually exclusive; an adult could have more than 1 dyad or triad.

The NHIS questions on chronic conditions included in this article remained consistent for the 2001 through 2010 NHIS surveys, with 1 exception: in 2001 the NHIS asked sample adults if they had arthritis, with no reference to rheumatoid arthritis, gout, lupus, or fibromyalgia. From 2002 and onward, the question on arthritis included all 5 conditions (ie, arthritis, rheumatoid arthritis, gout, lupus, and fibromyalgia). The 10 conditions included in this HHS standardized approach[14] that were not measured by the NHIS for those years were congestive heart failure, cardiac arrhythmias, hyperlipidemia, autism spectrum disorder, dementia, depression, human immunodeficiency virus infection, osteoporosis, schizophrenia, and substance abuse disorders (a few of these conditions were measured by the NHIS in some years). The inability to capture these additional conditions, especially those related to mental health among the younger population,[15] likely means percentages of MCC using the NHIS may be underestimates.[16] Health insurance categories were based on a hierarchy of mutually exclusive categories,[12,13] which included private coverage, public coverage (ie, Medicaid, Children's Health Insurance Program, or Medicare), other coverage (ie, state-sponsored health plans, other government programs, or military health plans), and uninsured.

Statistical Analysis

To account for survey weights that allow for generalization to the US adult civilian noninstitutionalized population and the additional covariance resulting from the complex cluster sampling design used by the NHIS, we used SUDAAN version 10.0.1 (RTI International, Research Triangle Park, North Carolina) to generate all descriptive estimates and their corresponding confidence intervals. Two-tailed significance tests were used to test for significant differences in prevalence among population subgroups in 2010, and all differences noted in this article are significant (P < .05) unless otherwise noted. Estimates with a relative standard error greater than 30% were considered unreliable and were not discussed. Data from the 2001 through 2010 NHIS surveys were used to examine the trends of MCC by sex, age, and selected race/ethnicity subgroups with sufficient sample sizes to generate statistically reliable estimates. The JoinPoint Regression Program version 3.5.1 (National Cancer Institute, Washington, DC) was used to identify whether an increasing or decreasing trend was significant. This software also identified "joinpoints," which are points in time where a change in trend occurs.[17]

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