Arthritis Prevalent: Especially Among Women

SUMMARY: Study results report the prevalence of arthritis.

ABSTRACT: Arthritis and other rheumatic conditions are among the most prevalent diseases in the United States, particularly for women and some racial/ethnic groups (1-3). In 1992, arthritis was the leading cause of disability and was associated with total direct and indirect costs of $64.8 billion (4); projections indicate that by 2020, arthritis will affect 59.4 million (18.2%) persons in the United States (1). Previous reports have documented marked differences in the prevalence rates of arthritis by age, sex, race, ethnicity, education, and body mass index (BMI) (1-3). To examine the relative importance of these factors, CDC used data from the 1989-1991 National Health Interview Survey (NHIS) and a multivariate model to estimate the independent effect of each factor on self-reported arthritis. This report summarizes the results of that analysis, which indicate that a higher risk for arthritis is associated with older age, overweight, or obesity and that a lower risk is associated with being Asian/Pacific Islander or Hispanic or with having a higher education level.

The NHIS is an annual national probability sample of the U.S. civilian, noninstitutionalized population (5). Estimates of the prevalence of arthritis were based on a one-sixth random sample (n=59,289) of respondents who answered questions about the presence of any musculoskeletal condition during the preceding 12 months and provided details about these conditions. Each condition was assigned a code from the International Classification of Diseases, Ninth Revision (ICD-9). This analysis used the definition of arthritis, which included arthritis and other rheumatic conditions, developed by the National Arthritis Data Workgroup (1) *. The final sample of 41,919 excluded persons aged less than 18 years (n=16,488), for whom self-reported height and weight were not asked, and persons aged greater than or equal to 18 years for whom such data were missing (n=882).

Multivariate logistic regression was used to assess the relation between self-reported arthritis and age, race, ethnicity, education, and BMI. Previous studies have documented that each of these variables is associated with arthritis (1-3,6-8). Because stratified analyses suggested that the effect of BMI on arthritis differed by sex, the model was applied separately to men and women. For this analysis, BMI (weight {kg}/height {m}2) was divided into four categories: underweight (BMI less than 20), normal weight (20 less than or equal to BMI less than 25), overweight (25 less than or equal to BMI less than 30), and obese (BMI greater than or equal to 30) (9). SUDAAN was used to weight observations and to account for the complex sampling design.

Of the 41,919 persons surveyed, 8706 (21%) reported having arthritis. Older age was the strongest overall predictor for self-reported arthritis among women, risk for arthritis varied directly with BMI. Among men, the risk was higher among those with greater BMI (odds ratio {OR}=1.3 {95% confidence interval (CI)=1.1-1.4} for overweight, OR=1.7 {95% CI=1.5-2.0} for obese), and those who were underweight (OR=1.4 {95% CI=1.0-1.8}), could cause chronic weight loss (e.g., infections and neoplasms). Risk for arthritis was similar by race for all groups except Asians/Pacific Islanders (OR=0.6 {95% CI=0.4-0.9}), and by ethnicity, was lower among Hispanics. For men, risk was lower for those who were college graduates (OR=0.8 {95% CI=0.7-1.0}) or who attended graduate school (OR=0.7 {95% CI=0.6-0.9}). Models using different BMI categories and models run without proxy-reported observations yielded similar findings.

Reported by: Dept of Epidemiology, School of Public Health, Univ of North Carolina, Chapel Hill. K Johnston-Davis, Association of Schools of Public Health, Washington, DC. Div of Adult and Community Health, National Center for Chronic Disease Prevention and Health Promotion, CDC.

Source: Center for Disease Control

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