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Keywords:

  • Lupus;
  • Children;
  • Cost;
  • Systemic lupus erythematosus

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

Objective

To determine the direct cost of care of children with childhood-onset systemic lupus erythematosus (cSLE), and to determine the direct cost per quality-adjusted life year (QALY) with cSLE.

Methods

Administrative databases from 2 large tertiary pediatric rheumatology centers in the United States were reviewed for all patients with cSLE (n = 119) diagnosed and regularly treated in these centers between January 2001 and April 2004. Health-related quality of life estimates for patients with cSLE (n = 297) reported in the literature were used to calculate QALYs based on global health ratings of the Child Health Questionnaire (range 0–100).

Results

Information on 3,184 patient-months of followup was included in the analysis. During a mean ± SD followup of 27 ± 11.8 months, the direct cost of care for the cohort amounted to $3,965,048, excluding outpatient medications. Irrespective of patient sex, the mean ± SD cost of cSLE per month was $1,245 ± $2,352, or ∼$14,944 per year. Inpatient and day hospital care accounted for 28% of the cost, laboratory testing accounted for 21%, inpatient/day-patient medication costs accounted for 13%, and dialysis accounted for 11%. Visits to the rheumatology clinic only contributed 9% to the direct cost of care. When including an estimated outpatient medication cost of $1,190, the direct cost of cSLE per QALY was $30,908.

Conclusion

Children diagnosed with cSLE were found to have a considerable direct cost of care. The treatment of cSLE appears to be far more costly than that of adult SLE and juvenile idiopathic arthritis reported in the literature.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

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).

PATIENTS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

Patients.

All patients with cSLE followed at 2 large pediatric rheumatology centers in the US were identified using clinical and administrative databases. Patients were included in the study if they fulfilled classification criteria of SLE (4) prior to the age of 19 years. In addition, all patients had to be followed and treated regularly for cSLE at these centers between January 2001 and May 2004. Patients who were seen <3 times or in intervals of >5 months were excluded because we assumed that these children received a large proportion of their cSLE therapy elsewhere.

Cost data.

Source of information.

Costs rather than charges are presented in US dollars. Costs occurring in the 3 earlier years were not adjusted for inflation. Annual cost was based on the sum of the captured cost divided by the total patient-years of followup.

Cost data were obtained from administrative databases. Therefore, cost accumulated by outpatient clinic visits and hospitalizations at medical centers not affiliated with the tertiary care centers were not captured, and were not considered in the analysis. We previously verified the accuracy of these databases for pediatric rheumatology patients and found 98% concordance between database entry and the health resource utilization documented in the medical record (5).

For the purpose of the study, cost items coded in the databases were grouped in several cost categories as follows: 1) inpatient and day-hospital care, which included the professional fees for physician consultations and other hospital services; 2) medications given during inpatient and day-hospital admissions; 3) emergency department visits; 4) radiology testing, which encompassed the cost of radiographs, magnetic resonance imaging, computerized tomograms, and interventional radiology procedures; 5) clinical testing, e.g., echocardiograms, electroencephalograms, and pulmonary function testing; 6) clinical services, e.g., services by allied health professionals such as social workers, nurses, dietitians, psychologists, and outpatient surgery (e.g., wart removal, skin biopsy); 7) laboratory testing including cost of phlebotomy; 8) outpatient rheumatology clinic visits; and 9) outpatient clinic visits within the tertiary care centers to ophthalmology, pulmonology, cardiology, neurology, and nephrology.

Estimate of outpatient medication cost.

The cost of outpatient medications was not consistently available. Therefore, we assumed that cSLE medication cost was comparable with that of adult patients with SLE and was, on average, a mean ± SD of $1,190 ± $800 per year (3).

Information on health-related quality of life in cSLE.

The Pediatric Rheumatology International Trials Organization and the Pediatric Rheumatology Collaborative Study Group have recently completed an international study on the health-related quality of life (HRQOL) of almost 300 children with cSLE (6). HRQOL was measured using the Child Health Questionnaire (CHQ) (7). Briefly, the CHQ is a generic HRQOL instrument that is modeled after the Medical Outcome Survey Shortform 36 and is designed to capture the physical, emotional, and social components of health status of children ages ≥5 years. The CHQ comprises 15 subscales and includes a rating of global health (range 0–100). For healthy children (n = 1,333), mean values between 83.6 and 94.6 using the CHQ global health scale have been reported (7).

Quality-adjusted life years with cSLE.

A QALY is the common currency to assess the extent of the benefits gained from treatments in terms of HRQOL. The results of the global health subscale of the CHQ were used to estimate QALY. On average, the mean ± SD global health of children with cSLE was rated at 52.2 ± 25.9 using the CHQ gobal health scale. Assuming that HRQOL was constant over time, cSLE was associated with 0.522 QALYs per year of followup.

Statistical analysis.

Data were analyzed using SAS 8.2 (SAS, Cary, NC) and EXCEL 2002 (Microsoft, Redwood, CA). Descriptive analysis was performed, and 2-group comparisons were based on Student's t-tests.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

Participants.

A total of 122 patients with cSLE were identified. Three patients seen during the study period were excluded due to inconsistent followup and because health care was mainly provided elsewhere. As expected, there was a female preponderance of 87% (female:male = 103:16). The mean ± SD duration of patient followup was 26.8 ± 11.8 months. Information on 3,184 patient-months of followup was included in the analysis.

Use of health care services.

During the study period, 87 (73%) of the patients required hospitalization or had at least 1 day-hospital visit. Fifty children (42%) presented to the emergency room at least once (Table 1). Ninty-one patients (76.5%) were seen in other clinics besides rheumatology, and 97 (81.5%) required radiology services.

Table 1. Use of health care services coded in administrative databases for 119 patients receiving the health care service
Health service/cost sourceNumber (%)
Laboratory testing119 (100)
Rheumatology visits119 (100)
Radiology tests97 (81.5)
Other clinic visits91 (76.5)
Inpatient care87 (73.1)
Clinical services and testing72 (60.5)
Emergency department50 (42.0)
Dialysis3 (2.5)

Direct cost of care.

Cumulative cost of care during the study period was $3,965,048 (Table 2). Inpatient and day-hospital care was the single largest cost entity, followed by the cost of laboratory testing and medications given during hospitalizations. Clinic visits contributed 20% to the direct cost of care. Although only 3 patients required dialysis, this service accounted for 11% of the direct cost of care. There was no difference in the cost of care between female and male patients.

Table 2. Direct cost of care in US dollars coded in administrative databases
Health serviceEntire cohort (3,184 patient-months of followup)Mean cost per patient during 12-month followupPercentage of direct cost of care
Inpatient or day-patient care$1,112,595$4,19328
Inpatient or day-patient pharmacy$530,662$1,83913
Laboratory testing$817,513$3,08121
Dialysis$426,752$1,60811
Rheumatology outpatient visits$373,919$1,4099
Other outpatient clinic visits$421,349$1,58811
Radiology department$132,313$4993
Clinical tests$41,780$1571
Clinical services$65,166$2462
Emergency department visits$42,999$1621
Total$3,965,048$14,944100

When outpatient medications were excluded, the mean ± SD cost of care per patient was $1,245 ± $2,352 (median $480, range $60–$21,645) per month or $14,944 ± $40,219 (median $5,700, range $60–$220,000) per year. Assuming the average annual medication cost of adults and children with SLE is similar ($1,190 per year of followup), the mean direct cost of care of cSLE including outpatient medications would be $16,134 per year.

Direct cost of cSLE per QALY.

Based on previous HRQOL estimates for children with cSLE (6), the mean annual direct cost of cSLE per QALY would be $30,908 ($16,134 divided by 0.522 QALYs per year of followup)

Estimate of the economic impact of cSLE in the US

The exact prevalence of cSLE is unknown. Based on previous reports and our own research, there are 12–50 children with cSLE per 100,000 children in the US (8, 9). Based on US Census 2000 information, there are 80.5 million children in the US, and therefore an estimated 9,666–40,275 children with cSLE (10). Assuming that the cost of care in our centers is representative of this population, and even if we considered only the direct cost captured by administrative databases, the economic burden of cSLE in the US would range from $146 million to $650 million annually.

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

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.

Acknowledgements

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES

The authors are indebted to E. Giannini, MSc, DrPH, for his thoughtful comments and editorial review of the manuscript.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. PATIENTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. Acknowledgements
  8. REFERENCES
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