Defining Arthritis for Public Health Surveillance: Methods and Estimates in Four US Population Health Surveys

Objective To determine the variability of arthritis prevalence in 4 US population health surveys. Methods We estimated annualized arthritis prevalence in 2011–2012, among adults age ≥20 years, using 2 definition methods, both based on self‐report: 1) doctor‐/health care provider–diagnosed arthritis in the Behavioral Risk Factor Surveillance Survey (BRFSS), National Health and Nutrition Examination Survey (NHANES), National Health Interview Survey (NHIS), and Medical Expenditure Panel Survey (MEPS); and 2) three arthritis definitions based on International Classification of Diseases, Ninth Revision, Clinical Modification (ICD‐9‐CM) criteria in MEPS (National Arthritis Data Workgroup on Arthritis and Other Rheumatic Conditions [NADW‐AORC], Clinical Classifications Software [CCS], and Centers for Disease Control and Prevention [CDC]). Results Diagnosed arthritis prevalence percentages using the surveys were within 3 points of one another (BRFSS 26.2% [99% confidence interval (99% CI) 26.0–26.4], MEPS 26.1% [99% CI 25.0–27.2], NHIS 23.5% [99% CI 22.9–24.1], NHANES 23.0% [99% CI 19.2–26.8]), and those using ICD‐9‐CM were within 5 percentage points of one another (CCS 25.8% [99% CI 24.6–27.1]; CDC 28.3% [99% CI 27.0–29.6]; and NADW‐AORC 30.7% [99% CI 29.4–32.1]). The variation in the estimated number (in millions) affected with diagnosed arthritis was 7.8 (BRFSS 58.5 [99% CI 58.1–59.1], MEPS 59.3 [99% CI 55.6–63.1], NHANES 51.5 [99% CI 37.2–65.5], and NHIS 52.6 [99% CI 50.9–54.4]), and using ICD‐9‐CM definitions it was 11.1 (CCS 58.7 [99% CI 54.5–62.9], CDC 64.3 [99% CI 59.9–68.6], and NADW 69.9 [99% CI 65.2–74.5]). Most (57–70%) reporting diagnosed arthritis also reported ICD‐9‐CM arthritis; respondents reporting diagnosed arthritis were older than those meeting ICD‐9‐CM definitions. Proxy response status affected arthritis prevalence differently across surveys. Conclusion Public health practitioners and decision makers are frequently charged with choosing a single number to represent arthritis prevalence in the US population. We encourage them to consider the surveys’ purpose, design, measurement methods, and statistical precision when choosing an estimate.