Jeffrey J. Sacks

Objective: To estimate the prevalence of and the annual number of ambulatory health care visits for pediatric arthritis and other rheumatologic conditions.Methods: We used physician office visit, outpatient department visit, and emergency department visit data from the 2001–2004 National Ambulatory Medical Care Survey and 2001–2004 National Hospital Ambulatory Medical Care Survey to estimate annual visits for the International Classification of Diseases, Ninth Revision, Clinical Modification codes thought to represent significant pediatric arthritis and other rheumatologic conditions (SPARC). We converted visit estimates into prevalence estimates using data on the number of prior annual visits per patient. Synthetic estimates for states were produced using national rates.Results: The average annualized estimate of the number of children with SPARC was 294,000 (95% confidence interval [95% CI] 188,000–400,000). The annualized number of ambulatory health care visits for SPARC was 827,000 (95% CI 609,000–1,044,000).Conclusion: Pediatric arthritis estimates have varied widely because it is an umbrella term for which there are many definitions and because it is a relatively uncommon condition from a population surveillance perspective. Our estimates suggest that arthritis‐related health care visits impose a substantial burden on the pediatric health care system. One advantage of this surveillance paradigm is that it has established a starting point for tracking the national prevalence of arthritis and rheumatologic conditions in children on an ongoing basis using existing infrastructure rather than expensive new surveys. This surveillance system will help us monitor and predict the health care needs of patients with these conditions.

To assess whether self-reports of chronic joint symptoms or doctor-diagnosed arthritis can validly identify persons with clinically verifiable arthritis. The Behavioral Risk Factor Surveillance System (BRFSS), a telephone health survey, defines a case of arthritis as a self-report of chronic joint symptoms (CJS) and/or doctor-diagnosed arthritis (DDx). A sample of health plan enrollees aged 45-64 years and >/= 65 years with upcoming annual physical examinations were surveyed by telephone using the 2002 BRFSS CJS and DDx questions. Based on responses (CJS+, DDx-; CJS-, DDx+; CJS+, DDx+; CJS-, DDx-), respondents were recruited to undergo a standardized clinical history and physical examination for arthritis (the gold standard for clinical validation). Weighted sensitivities and specificities of the case definition were calculated to adjust for sampling. Of 2180 persons completing the telephone questionnaire, 389 were examined; of these, 258 met the case definition and 131 did not. For those examined and aged 45 to 64 years (n = 179), 96 persons had arthritis confirmed, of whom 76 met the case definition. Among those examined and aged >/= 65 (n = 210), 150 had arthritis confirmed, of whom 124 met the case definition. Among those without clinical arthritis, 45 of 83 of those aged 45 to 64 years and 40 of 60 of those aged >/= 65 did not meet the case definition. For those aged 45 to 64 years, the weighted sensitivity of the case definition in this sample was 77.4% and the weighted specificity was 58.8%; for those aged >/= 65, the sensitivity was 83.6% and specificity 70.6%. CJS+ had higher sensitivity and lower specificity than DDx+ in the younger age group; CJS+ and DDx+ behaved more comparably in the older age group. The case definition based on self-reported CJS and/or DDx appeared to be sensitive in identifying arthritis, but specificity was lower than desirable for those under age 65 years. Better methods of ascertaining arthritis by self-report are needed. Until then, a change in the surveillance case definition for arthritis appears warranted.