Prevalence of Arthritis and Arthritis-Attributable Activity Limitation by Urban-Rural County Classification — United States, 2015

Rural populations in the United States have well documented health disparities, including higher prevalences of chronic health conditions (1,2). Doctor-diagnosed arthritis is one of the most prevalent health conditions (22.7%) in the United States, affecting approximately 54.4 million adults (3). The impact of arthritis is considerable: an estimated 23.7 million adults have arthritis-attributable activity limitation (AAAL). The age-standardized prevalence of AAAL increased nearly 20% from 2002 to 2015 (3). Arthritis prevalence varies widely by state (range = 19%–36%) and county (range = 16%–39%) (4). Despite what is known about arthritis prevalence at the national, state, and county levels and the substantial impact of arthritis, little is known about the prevalence of arthritis and AAAL across urban-rural areas overall and among selected subgroups. To estimate the prevalence of arthritis and AAAL by urban-rural categories CDC analyzed data from the 2015 Behavioral Risk Factor Surveillance System (BRFSS). The unadjusted prevalence of arthritis in the most rural areas was 31.8% (95% confidence intervals [CI] = 31.0%–32.5%) and in the most urban, was 20.5% (95% CI = 20.1%–21.0%). The unadjusted AAAL prevalence among adults with arthritis was 55.3% in the most rural areas and 49.7% in the most urban. Approximately 1 in 3 adults in the most rural areas have arthritis and over half of these adults have AAAL. Wider use of evidence-based interventions including physical activity and self-management education in rural areas might help reduce the impact of arthritis and AAAL.

BRFSS is an ongoing, state-based, random-digit–dialed landline and cellphone survey of the noninstitutionalized adult population aged ≥18 years of the 50 states, the District of Columbia (DC), and the U.S. territories. BRFSS, designed to provide national and state-level estimates, collects data on health-related risk behaviors and chronic health conditions. Among the 2015 BRFSS respondents surveyed in the 50 states and DC, complete information on age, county, and arthritis diagnosis was available for 426,361 (98.2%). The median combined response rate for the 2015 BRFSS was 47.2% and ranged from 33.9% in California to 61.1% in Utah.* Respondents were classified as having arthritis if they answered “yes” to the question, “Have you ever been told by a doctor or other health professional that you have some form of arthritis, rheumatoid arthritis, gout, lupus, or fibromyalgia?” Among adults with arthritis, AAAL was identified by a “yes” response to the question, “Are you now limited in any way in any of your usual activities because of arthritis or joint symptoms?”

Counties were classified into six urban-rural categories using the National Center for Health Statistics 2013 Urban-Rural Classification Scheme for Counties,^† based on 2010 U.S. Census data and the 2013 Office of Management and Budget designations of metropolitan statistical areas, micropolitan statistical areas, and noncore areas. The county classification categories from most urban to most rural are 1) large central metropolitan (city); 2) large fringe metropolitan (suburb); 3) medium metropolitan; 4) small metropolitan; 5) micropolitan; and 6) noncore (rural).

Unadjusted overall, age-specific, and age-standardized prevalence with CIs were estimated for arthritis and AAAL by urban-rural categories. Age-standardized prevalence by urban-rural categories was further stratified by selected demographic (sex, race/ethnicity, highest education level, and employment status) and health (body mass index, leisure time physical activity, self-rated health, disability, and smoking status) characteristics. Estimates were age-standardized to the 2000 U.S. standard population aged ≥18 years using three age groups (18–44 years, 45–64 years, and ≥65 years).^§ All analyses accounted for the complex sampling design of the survey, with sampling weights created using raking methodology. This methodology allows incorporation of many demographic variables into the weighting process, including telephone source, which makes the sample more representative of the population and reduces the potential for bias. Statistical significance was determined using t-tests at α = 0.05 with the most rural (noncore) category as the reference group.

In the most rural areas (noncore) nearly 1 in 3 adults (unadjusted prevalence 31.8%) reported having doctor-diagnosed arthritis (Table 1). Age-specific prevalence was higher in older age groups and in rural areas. In age-standardized analyses, the prevalence of arthritis was lower among adults living in the most urban areas (20.0%; 95% CI = 19.6%–20.5%), and higher among adults living in the most rural areas (26.9%; 95% CI = 26.2%–27.5%) (Table 1) (Figure). Age-standardized arthritis prevalence was higher in rural areas among most subgroups studied. Across all urban-rural categories, arthritis prevalence followed previously reported patterns for U.S. adults: higher prevalence among women, older adults, smokers, adults with less education, adults who are less physically active, or adults with higher body mass index. Arthritis prevalence was ≥50% among adults aged ≥65 years across all urban-rural categories (50%–55%), adults unable to work because of disability in all but the most urban categories (50%–57%), and adults reporting any functional disability in the most rural category (50%) (Table 1).

AAAL affected about half of adults with arthritis in all urban-rural categories; unadjusted overall prevalence ranged from 47.8% to 55.3% (Table 2). Age-specific prevalence of AAAL was higher in rural areas and among persons aged 45–64 years in all areas. In age-standardized analyses, the overall prevalence of AAAL was lower among adults in the most urban category (47.1%, 95% CI = 44.9%–49.3%), and higher in the most rural (56.9%, 95% CI = 54.6%–59.2%) (Table 2). Across the majority of health characteristic and demographic subgroups studied, higher prevalences of AAAL were found in the most rural (noncore) category (Table 2).

Corresponding author: Michael Boring, MBoring@cdc.gov, 404-498-5148.

¹Division of Population Health, National Center for Chronic Disease Prevention and Health Promotion, CDC.

References

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TABLE 1. Prevalence of doctor-diagnosed arthritis (crude and age-standardized) among U.S. adults aged ≥18 years, by urban-rural status and selected characteristics — Behavioral Risk Factor Surveillance System, 2015*

Abbreviations: CI = confidence interval; HS = high school; UR = unreliable.
* Estimates are weighted and account for the complex sampling design.
^† Estimates age-standardized to the 2000 U.S standard population aged ≥18 years using three groups (18–44 years, 45–64 years, ≥65 years).
^§ Estimates are unreliable and are suppressed (sample size <50 or relative standard error >30%).
^¶ Respondents were classified as active if they reported ≥150 minutes of moderate intensity leisure time aerobic physical activity per week, insufficiently active if they reported 1–149 minutes, and inactive if they reported 0 minutes. Reported vigorous intensity physical activity minutes were counted double and added to moderate intensity physical activity minutes.
** Respondents were classified as functionally disabled if they answered yes to any of the following five questions: “Because of a physical, mental, or emotional condition, do you have serious difficulty concentrating, remembering, or making decisions?”; “Do you have serious difficulty walking or climbing stairs?”; “Are you blind or do you have serious difficulty seeing, even when wearing glasses?”; “Do you have difficulty dressing or bathing?”; “Because of a physical, mental, or emotional condition, do you have difficulty doing errands alone such as visiting a doctor’s office or shopping?”

FIGURE. Age-standardized arthritis prevalence, by urban-rural categories — Behavioral Risk Factor Surveillance Survey, United States, 2015

The figure above is a bar chart showing the age-standardized arthritis prevalence, by urban-rural categories, in the United States during 2015.

TABLE 2. Prevalence (crude and age-standardized) of arthritis-attributable activity limitation (AAAL) among adults aged ≥18 years with doctor-diagnosed arthritis, by urban-rural status and selected characteristics — Behavioral Risk Factor Surveillance System, 2015*

Abbreviations: CI = confidence interval; HS = high school, UR = unreliable.
* Estimates are weighted and account for the complex sampling design.
^† Analysis for AAAL prevalence excluded respondents where AAAL could not be ascertained (Don’t know/Not sure, Refused, or missing).
^§ Estimates are age-standardized to the 2000 U.S standard population aged ≥18 years using three groups (18–44 years, 45–64 years, ≥65 years).
^¶ Estimates are unreliable and are suppressed (sample size <50 or relative standard error >30%).
** Respondents were classified as active if they reported ≥150 minutes of moderate intensity leisure time aerobic physical activity per week, insufficiently active if they reported 1–149 minutes, and inactive if they reported 0 minutes. Reported vigorous intensity physical activity minutes were counted double and added to moderate intensity physical activity minutes.
^†† Respondents were classified as functionally disabled if they answered yes to any of the following five questions: “Because of a physical, mental, or emotional condition, do you have serious difficulty concentrating, remembering, or making decisions?”; “Do you have serious difficulty walking or climbing stairs?”; “Are you blind or do you have serious difficulty seeing, even when wearing glasses?”; “Do you have difficulty dressing or bathing?”; “Because of a physical, mental, or emotional condition, do you have difficulty doing errands alone such as visiting a doctor’s office or shopping?”