Prevalence of Arthritis
Summary written by Kevin Fontaine, Ph.D.
Arthritis and other rheumatic diseases are the most frequent cause of disability and cost an excess of $15 billion dollars in direct medical costs annually. Because arthritis is such a disabling and costly disease, Mili and colleagues sought to estimate, using recent population-based survey data, the prevalence of arthritis among adults and to identify subgroups that have a high prevalence of arthritis (Journal of Rheumatology, 29, 1981-1988).
Methods: Using data from the 1996-1999 Behavioral Risk Factor Surveillance Survey (BRFSS), a telephone survey of a representative sample of non-institutionalized adults aged 18 years or older, they estimated the prevalence of self-reported arthritis, defined as chronic joint symptoms or doctor diagnosed arthritis. Data were obtained from 15 states and Puerto Rico that included the optional arthritis survey module of the BRFSS.
Results: Among the 54,169 BRFSS respondents, 17,556 reported having arthritis (~32%). After adjusting the estimates for age, they found that arthritis was more common among several subgroups not previously recognized to have high prevalence rates of arthritis. Specifically, current and former smokers, divorced or separated respondents, and those out of work or unable to work were found to have high rates of arthritis. As expected, arthritis was also more prevalent among older adults, women, those with low education, the physically inactive, overweight and obese respondents, and respondents with low household incomes.
Conclusion: The self-reported prevalence of arthritis is higher than previously estimated. Apart from traditional risk factors for having arthritis such as increased age and obesity, a number of additional risk factors have been identified including a history of smoking and being divorced.
Editorial Comments: This study provides the most recent estimate of the prevalence of arthritis and suggests that certain subgroups may be at higher risk of arthritis than previously thought. For example, compared to non-smokers, daily smokers had 60% higher prevalence rate ratios. This new finding suggests that there may be more risk factors for arthritis than previously thought. However, several limitations preclude making definitive statements about the validity of these newly identified risk factors. First, BRFSS data are self-reported and does not specify the type of arthritis reported. Second, these findings were derived only from 15 states and Puerto Rico, thus they may not generalize to the entire United States. Finally, because the BRFSS survey is cross sectional, we cannot assess causality of the associations between arthritis and the variables under study. Indeed, there is no plausible mechanism by which many of the newly identified risk factors (being divorced, for example) might put people at greater risk of having arthritis.
Nonetheless, the results of this new study may prove to be important. That is, if, indeed, new high risk groups have been identified, health care professionals should consider asking patients in these high risk groups about arthritis symptoms. Since it is estimated that 16% of people with arthritis never report it to their doctor or seek treatment, it may be possible to reduce the disability and functional decline from arthritis if it is identified and treated promptly. Moreover, if additional work confirms the validity of these new risk factors, public health interventions could be developed that are targeted to these subgroups to reduce the burden of arthritis.