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- PATIENTS AND METHODS
In the current political atmosphere of limited health care budgets, it is increasingly important to determine economic consequences of disease. Therefore, in recent years, economic assessments of musculoskeletal diseases have received considerable attention. Cost analyses are conducted because they are considered an important step towards performing complex economic evaluations. Although cost studies cannot determine whether the health care expenses are worth paying for, they are suitable for determining the magnitude of a problem and identification of areas for further resource allocation. Cost analyses are often aimed towards determing the total cost of care. Total cost is the sum of so-called “direct” and “indirect” (also time-related) cost. The term direct cost typically encompasses expenses that are directly attributable to medical care and therapies. Conversely, indirect cost to the family or to the society at large arises from loss in work productivity and lost hours of work.
There is a small body of literature addressing the economic impact of adult systemic lupus erythematosus (SLE) in the US. The mean ± SD direct cost for an adult with SLE was recently estimated to be $4,170 ± $800 per year, with medication cost contributing $1,190 to the direct cost (1). In 2003, the indirect cost of musculoskeletal diseases was estimated to contribute 58% to the total cost of these diseases in the US (2). The indirect cost of SLE may be higher than that of other rheumatic diseases. A British study estimated that the indirect cost of SLE due to loss of working hours and unemployment was twice as high as the direct cost of SLE (3).
Childhood-onset systemic lupus erythematosus (cSLE) is among the most care-intensive diseases treated by pediatric rheumatologists. Compared with their adult counterparts, children with cSLE have a longer life expectancy, and the disease remits in few patients. No information is available on health care expenses associated with cSLE in the US. Therefore, the aim of the present study was to measure the direct cost of care of cSLE and to estimate the direct cost of care per quality-adjusted life year (QALY).
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- PATIENTS AND METHODS
Children with cSLE often require multiple medications and close followup by pediatric rheumatologists and other pediatric subspecialists to control the disease. The direct cost of care of cSLE has not been determined in the past. The current data suggest that the cost of cSLE may be considerably higher than the cost of care of adults with SLE (1, 3).
Our study supports previous reports of adult SLE, where inpatient or day-hospital care was the single largest cost factor (3). The observation that patients with cSLE frequently present to the emergency department but that the cost of emergency department visits is relatively small compared with the total cost of care in cSLE was similar to the experience of adults with SLE (3).
Laboratory testing for cSLE was expensive and extensive. Reasons may include frequent multiorgan involvement with cSLE, but also the lack of reliable and valid biomarkers of cSLE disease activity to help guide therapeutic decisions. Although the absolute cost of laboratory testing with cSLE appeared to be higher than with SLE in adults, possibly due to a lack of important comorbidities, the relative contribution of labortatory testing to the direct cost of care was even somewhat lower for cSLE than that reported for US adults with SLE (1).
Despite the fact that only a few children had renal failure requiring dialysis, the cost of this therapy contributed 11% to the direct cost of care, constituting the fourth largest cost entity. Therefore, based on previous research in adults, dialysis expenses contribute to the direct cost of both SLE and cSLE in similar proportions (1). This finding suggests that prevention and aggressive therapy of renal disease are not only of utmost importance for avoiding patient damage (11) but also appear to be relevant for containing the cost of care of cSLE.
When compared with the cost of other chronic childhood diseases, the cost associated with cSLE is considerable. The findings of this study suggest that the direct cost of care for cSLE far exceeds those for long-standing juvenile idiopathic arthritis (JIA) (12–14). Minden et al (12) estimated that the mean direct cost of JIA is 3,471 euros annually (1 euro = US $0.75; ∼$4,160), making cSLE therapy 3–4 times more expensive than JIA therapy.
Previous studies examining the cost of adult SLE health services used a slightly different valuation system than that used in the current study. Nonetheless, using a conservative estimate, the direct cost of care for a child with cSLE appears to be roughly 3 times higher than for an adult with SLE. Whether this difference in cost between adults and children is due to differences in health care delivery systems, adherence to therapies, or differences in disease severity remains to be determined (15).
Based on experiences from other chronic diseases including SLE, patient nonadherence to therapeutic regimens is likely an important factor in increasing the cost of care of both SLE and cSLE over time (16, 17). Beyond anecdotal experience, there is no published evidence supporting the idea that adolescents with cSLE are importantly less adherent to medications and clinic visits than their adult counterparts. Future studies are required to more closely examine the effects of therapy adherence on the cost of care in both SLE and cSLE.
The impact of disease duration, time to referral to a specialty clinic, disease activity, and disease damage on the cost of care of adults with SLE is still being investigated. A recent study on cost of care of Medicaid patients diagnosed with SLE in California suggests that the cost of care of non-Hispanic patients remains stable over time (18), e.g., is unrelated to disease duration. Conversely, statistically significant positive associations of increased cost of care with disease activity and damage have been reported for adults with SLE (1, 3). A limitation of our study is that we lacked information of patient disease activity over time, disease duration, time to referral to a pediatric rheumatologist, and disease damage. However, predictive models of the cost associated with cSLE was not an objective of this study, and our ongoing research will address more specifically predictors of cost of care of cSLE.
Another limitation of our study may be that children with cSLE at tertiary care centers could have more severe disease, leading to an overestimation of cSLE cost of care. However, most patients with cSLE have significant disease involvement, making it very likely for them to present to pediatric rheumatology clinics. Furthermore, cost estimation studies for adult patients with SLE were also performed at tertiary rheumatology centers, facilitating the comparison of adult and pediatric data (1, 19).
In addition, no information on medication or indirect cost was available. We assumed that medication requirements for children and adults are similar, although previous research suggests that children with cSLE require more intensive therapies (15, 20). Therefore, using this conservative estimate, we probably underestimated the true direct cost of cSLE care. Indirect cost of cSLE has not been measured in the past. Likely indirect costs of pediatric and adult disease are not comparable. Using a conservative approach, previous studies in adult SLE suggest that the annual indirect cost is approximately twice as high as the direct cost and exceeds $7,000. Conversely, Minden et al (12) suggest that the indirect cost (including copayments) of JIA is roughly 50% of the direct cost. Given the variance in these estimates, it appears to be difficult to estimate the indirect cost of cSLE. However, even if the indirect cost is neglected, the cost of cSLE care appears to be substantial.
In summary, we have shown that the per-patient health care cost of cSLE is considerable and appears to exceed that of adult SLE and JIA. In particular, research of treatments aimed at reducing the frequency and duration of inpatient care and dialysis seems to have a high potential for decreasing health care expenses in cSLE.