Information about the economic impact of illness has become central to health policy debates, affecting the allocation of research funding among conditions and the choice of therapies for specific conditions. Because of the growing importance of cost of illness studies in health policy, the literature concerning the cost of all forms of musculoskeletal conditions for the US as a whole (1–8) and for other nations (9–13), as well as the cost of specific musculoskeletal conditions, including various forms of arthritis and other rheumatic conditions (AORC) (14–37), has been expanding rapidly.
In general, the studies of the economic impact of all forms of musculoskeletal conditions have been derived from population-based surveys, but not directly observed individual-level medical care expenditures or employment status and earnings. In contrast, studies that have tracked the actual costs or expenditures for individuals have used clinical-based samples and are, thus, not representative of the general population. In the present study, we used the results of the Medical Expenditures Panel Survey (MEPS), which melds the methods of the 2 kinds of studies by using a population-based sampling frame and then prospectively tracking actual expenditures and employment and earnings among respondents.
The specific goals of the study were as follows: 1) to provide estimates of all medical care expenditures on behalf of all persons with any form of AORC in the US in 1997, estimates of the increment in expenditures that was specifically attributable to the AORC among persons ages 18 years and older, and estimates of the fraction of total medical care expenditures attributable to the AORC and 2) to provide estimates of lost earnings among persons with AORC ages 18–64 years and estimates of the increment in lost earnings attributable to the AORC among persons of these ages.
A method developed by the investigators in an earlier study concerning all forms of musculoskeletal disease (7) was used to estimate the increment in medical care expenditures attributable to AORC. An expansion of that method was used to estimate the increment in earnings losses.
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- SUBJECTS AND METHODS
We performed 2 kinds of estimates of both the medical care expenditures and earnings losses associated with arthritis and other rheumatic conditions. In the first estimate of medical care expenditures, we recorded the magnitude and distribution of all medical care expenditures among the 38.423 million persons with AORC, and we found that such persons experienced mean total expenditures of $4,865, or $186.9 billion overall. Hospital admissions accounted for 39% of these expenditures; ambulatory care (29%) and prescription drugs (14%) were the next 2 largest components. Although average expenditures of $4,865 among persons with AORC were substantial, most individuals avoided such high levels of expenditures. Among persons with AORC alone, the average expenditures were only $1,074 and, even at the 95th percentile, were relatively small ($3,703). Among persons with both AORC and non-AORC chronic conditions, median expenditures were only $2,004 and only rose to $5,114 at the 75th percentile.
Nevertheless, expenditures incurred on behalf of persons with AORC represent a substantial drain on the nation's economy. In 1995, the National Arthritis Data Workgroup reported that both direct and indirect costs of all forms of musculoskeletal conditions, including AORC, for 1988 was 2.5% of the gross national product of the US (6). In the present study, however, we found that total medical expenditures for AORC alone in 1997 were equivalent to ∼2.3% of the gross domestic product for that year (48), and would suggest that both the accounting methods used in the MEPS and the aging of the population may have contributed to the increase in the estimated impact of these conditions.
In the second set of analyses of medical care expenditures, we estimated the proportion of total expenditures attributable to AORC among persons ages ≥18 years. Overall, AORC was associated with an attributable fraction of 10% for medical expenditures, or $1,391 per person with AORC, which aggregates to $51.1 billion, the equivalent of about 0.6% of the gross domestic product in 1997. Since in a recession, by definition, the economy retrenches by ≥1% of the gross domestic product for at least 2 consecutive quarters, the increment in medical care expenditures attributable to AORC has an impact slightly less than that of a small recession, but unlike a recession, it occurs in perpetuity.
In the unadjusted analysis, persons with AORC ages 18–64 years who were not working were estimated to be responsible for $73.2 billion in earnings losses, while those who were employed were responsible for losses of $9.2 billion, resulting in an estimate of net earnings losses of $82.4 billion. The finding that those who were not employed were responsible for the bulk of the lost income is consistent with clinical studies in specific rheumatic conditions that have shown a total loss of employment to be more common than a reduction in hours or a change in work activities (49). After controlling for demographic characteristics and comorbidity, the incremental value of the aggregate net earnings gap attributable to AORC was ∼$35.1 billion, or $1,579 per person with AORC ages 18–64 years.
In a recent estimate of the economic burden of musculoskeletal conditions, Rice and colleagues (1) calculated that the direct costs of AORC in 1995 were $21.7 billion, or about $22.8 billion in 1997 dollars. In the present study, we estimated that the increment in medical care expenditures attributable to AORC was $51.1 billion in 1997 dollars. Thus, the direct accounting of medical care expenditures made possible by the development of the MEPS may have resulted in a substantial increase in the estimate of the direct costs attributable to AORC. In the same study by Rice, it was estimated that the indirect costs of AORC among persons ages 18–64 years were $60.8 billion in 1995, or about $64.0 billion in 1997 dollars. Thus, the estimate of the earnings losses attributable to AORC in the current study ($35.1 billion) is considerably smaller than the estimate made by Rice and colleagues. The ability to control for differences in characteristics other than the AORC between persons with and without AORC may account for the lower estimate in the present study. The estimate of earnings losses, however, is within the range of estimates reported by Dunlop and colleagues (8).
Some AORC conditions were excluded from the analysis because 4-digit ICD-9 data that would identify these conditions were not available. This underestimation of cost was likely balanced by the presence of some non-AORC conditions that were included in the analysis because 3-digit ICD-9 codes are less specific.
There are 4 reasons why medical care expenditures may have been underestimated in this study. First, the study sample was limited to the US civilian noninstitutionalized population and, thus, expenditures by institutionalized and military populations were not included. Second, the MEPS measures only medical expenditures and does not capture services for which there is no exchange of money. Third, we did not include in this analysis expenditures for complementary and alternative medicine, which is becoming an increasingly common treatment modality, especially among individuals with AORC (50, 51). Fourth, the data from the current study precede the introduction of biologics for the treatment of rheumatoid arthritis, more-aggressive testing for the presence and treatment of osteoporosis, and the growth of the coxibs and/or the use of proton-pump inhibitors with traditional nonsteroidal antiinflammatory drugs. However, it should be pointed out that the relatively low prevalence of RA means that the introduction of biologics would add, at most, several billion dollars to the estimate of the aggregate increment of ∼$51 billion that was attributable to all forms of AORC. Moreover, although it is becoming increasingly common to prescribe bone densitometry for women at risk of developing osteoporosis, the added costs of such testing would be balanced by the reduction in the number of women receiving estrogen replacement therapy. Nevertheless, all of these developments have undoubtedly increased the incremental costs associated with AORC since 1997, making the estimates of the present study relatively conservative.
There are some limitations that would apply to the estimates of the increment in direct and indirect costs. The MEPS survey provides no information with which to estimate whether persons with AORC differ from the rest of the population in their level of perseverance in the face of medical symptoms with respect to the kinds of medical care services procured or their willingness to stay at work.
These 1997 cost estimates, and the 1996 expenditures presented by Dunlop et al (8), are the first national population–based AORC cost estimates based on directly observed individual-level expenditure and employment data. This study is the first to provide attributable fractions for medical care expenditures due to AORC. These expenditure estimates are an essential component of the ongoing effort by the Centers for Disease Control and Prevention to characterize the burden of AORC in the US for a single year, 1997. Thus far, the impact of AORC on hospitals (52) and ambulatory care (47, 53) has been reported, and these data will soon extend to characterizing the burden of AORC in nursing homes and assessing mortality rates among persons with AORC.
The results reported here indicate that a larger proportion of the indirect costs (41% of all $82.4 billion in indirect costs, or $35.1 billion) than of the direct costs (29% of all $186.9 billion, or $51.5 billion) of AORC is attributable to the AORC. This finding from a population-based study of persons with all forms of AORC is consistent with studies of persons with discrete rheumatic conditions (19) and indicates that the prevention of work loss and the resultant earnings losses should be central to public health policy aimed at reducing the impact of AORC, even as the cost of medical care continues to garner a disproportionate amount of the public's attention.