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- PATIENTS AND METHODS
Different studies have shown that musculoskeletal disorders have a great impact on individuals and society because of their high prevalence, morbidity and disability potential, and large use of acute and long-term health care and support resources (1, 2). Rheumatoid arthritis (RA) represents the paradigm of chronic inflammatory musculoskeletal disorder with a high prevalence and a progressive clinical course negatively affecting patients' quality of life, function, and life expectancy. Besides the consequences on the health status of individuals, RA has a substantial economic impact on patients, their families, and society (3–6).
Health economic studies are now an essential part of health care evaluation. The cost of any condition can be divided into 3 major components (7, 8). Direct costs include all expenses requiring actual payment or time spent due to the disease itself or to disability. Indirect costs represent the loss of resources as a consequence of work disability or unemployment. Finally, intangible costs are those related to decrease in quality of life and are not easily estimated because of difficulties in quantifying these dimensions of disease.
The annual costs of RA have been estimated to be 2 billion dollars in England in 1992 (9) and 8.7 billion dollars in the US in 1991 (10). Approximately half of these costs were direct costs and half were related to loss of productivity among working-age patients. However, only a few studies have addressed determinants of costs in RA from a societal perspective (11, 12). Factors influencing total costs of RA might help clinicians and decision makers in rationalizing resource allocation in a time of economic constraints for social and health care services. We analyzed individual and social factors influencing costs of RA in Spain from a societal point of view and by using a prevalence-based approach.
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- PATIENTS AND METHODS
We have analyzed annual costs of RA in a large retrospective cohort of patients referred to specialized care in a tertiary hospital. Our sample was representative of RA patients in our health district (14) and similar to other cohorts of RA patients reported (15, 16). We found an annual cost per RA patient of $11,341 in 2001 US dollars, approximately 90% of this amount attributable to the RA itself. The RA-related costs approached 100% of total costs when indirect costs and direct nonmedical costs were analyzed separately, reflecting that costs of RA are in a large proportion the costs of disability caused by disease. However, RA-related health care costs represented only 80% of total costs, reflecting the coexistence of different, non-RA-related, comorbid conditions in a substantial number of patients. Thus, the annual total cost per patient attributable to RA was $10,419, with a sensitivity analysis showing a lower cost of $7,914 and a higher cost of $12,922 per year. Our data falls in the range of other studies showing estimates of annual cost ranging from $5,300 to $7,000 per patient (9, 17). Because the prevalence of RA in Spain has been estimated at 0.5% of the general population (18), the annual economic impact of RA over the Spanish society might be more than $2 billion, which highlights the substantial burden that RA imposes on industrialized societies.
Direct costs represented the largest contributor to the total cost of disease (almost 70% of the global economic burden of RA). This distribution of costs is similar to that reported in Canada (17), but differs from other studies in which direct costs represented no more than 50% of total costs (9, 10, 19). These discrepancies might be explained by differences either in the intrinsic characteristics of each study population, health care system organization, or the methodology employed. Our patients made little use of long-term institutionalization but showed notable use of different forms of long-term care and help at home, including informal care delivered by relatives or informal caregivers. Because unpaid time was categorized among indirect costs in some studies and it represented more than 22% of direct costs in our study, the differences with other studies might be related both to specific definition of direct costs and a different pattern of use of sociosanitary resources, that is, all those related to a person's care. Admissions for orthopedic surgery and drug therapies, accounting for 17% and 11% of direct costs, respectively, were also major contributors to direct costs (12, 17, 20).
Productivity losses caused mainly by PWD of active workers and by the temporary or permanent disability of housewives to perform their duties at home accounted for the major part of indirect expenses. Similar results have been published in other studies (17), and differences with other studies (8–10, 19, 21–24) might be due to the relatively low rate of active workers in our population and the underestimation of the economic burden of “work disability of house keepers” as described by Reisine (25, 26). We did not include as production losses unemployment status or premature deaths (21).
Several variables were associated with higher RA-related costs. Duration of disease had a bimodal association with costs attributable to RA, with patients both with initial disease and long-lasting disease incurring higher costs than people with an intermediate duration of disease. The higher cost in patients with long-term RA was attributable both to direct and indirect costs (11), reflecting the impact of RA over function along years of disease, especially in terms of PWD. Conversely, patients with early disease incurred mainly direct costs, reflecting the intensive use of diagnostic and therapeutic procedures in these phases of the disease. However, duration of disease lost its statistical significance at the multivariate analysis when the HAQ score was introduced to the model.
We found an increment of $8,084 per year per unit of HAQ score. Similar associations with HAQ score have been reported (11, 12), suggesting that functional disability is a major determinant of costs in RA. However, we also observed that PWD attributable to RA and inability to perform housework tasks were also independently associated with higher costs. This suggests that the spectrum of RA-related disability is broader than the functional disability measured by HAQ score and has some distinct peculiarities in active workers and housekeepers. Our results confirm the strong link between disability and cost in RA and extend this connection not only to functional disability but also to other forms of measuring handicap in RA patients.
We did not find any relationship between different descriptive occupational variables and costs, but the low rate (11%) of active employed people in our sample as compared with other studies (12, 17, 19) do not allow firm conclusions. It has been described that workers with RA who can pace their own rhythm of work are more likely to continue performing their jobs (27). Because the low rate of active people in our sample was at least partially caused by an increased number of unemployed and permanently disabled individuals, one would hypothesize that the analysis of the sociolaboral context might be extremely useful to palliate the negative impact of RA in the workforce.
In conclusion, our data shows a global impact of RA similar to other studies, and links the costs of the disease mostly to its impact in function and the degree of disability of the patients. Although there is a great deal of consensus on the individual and societal advantages of an early and more efficient therapy of RA (24, 28, 29), it should be emphasized that disability is multidimensional and often the result of an ecological gap between environment demands and individual skills. For this reason, a coherent social response to RA would include preventive programs, aiming to reduce the levels of disability and institutional care, without promoting inadequate self or family care.