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Abstract

Background: SARDs (Systemic Autoimmune Rheumatic Diseases) are a group of rare, chronic conditions (systemic vasculitis, systemic lupus erythematosus, scleroderma, Sjogren's disease, and poly/dermatomyositis) associated with high health resource consumption. However, estimates of their healthcare burden are sparse, with most determined at tertiary centres over short periods. Studying them separately has also limited research progress. Here we grouped the SARDs, for the first time ever, to quantify their collective, longitudinal (twelve-year) burden at the population-level. Methods: A population-based cohort of SARDs cases was identified from the administrative database of BC’s single-payer health system (PopDataBC). A detailed algorithm, with time and specialist parameters, was used to enhance diagnostic specificity. From PopDataBC, all provincially-funded health services, and all prescriptions (regardless of funding source), consumed from 1996 -2007 were captured. Costs for outpatient services and prescriptions were summed directly from paid claims; case-mix methodology was used for most hospitalizations. To quantify their net burden, costs were summed for claims attributable (under broad and narrow definitions) to SARDs. Costs are reported in 2007 Canadian dollars. Results: 18,741 SARDs cases were identified, contributing 82,140 patient-years(PY). After inflation adjustments, the annual mean per-PY direct medical costs of SARDs averaged $6,954/PY, with $1,882/PY(27%) from outpatient, $3,551/PY(51%) from hospital, and $1,521/PY(22%) from prescriptions. Over twelve years, annual costs decreased by 32%, from $8,901/PY in 1996 to $6,087/PY in 2007. Outpatient costs and encounters decreased by 26% ($2,205-$1,641/PY) and 19% (34-27/PY), respectively. Mean annual hospital costs decreased by half ($5,579-$2,776/PY), and admissions by 46% (0.89-0.48/PY). Despite these decreases, the annual mean number of dispensed prescriptions increased by 49% (23-34/PY), and their costs by 50% ($1,117-$1,670/PY). The annual net per-PY costs of SARDs, mainly from hospitalizations(18-43% of costs) and prescriptions(48-76%), averaged $2,011-$3,202/PY. Conclusions: SARDs impart a substantial healthcare burden at the population level, and in 2007 were directly responsible for ≥44% of cases’ gross mean annual healthcare costs ($6,087/PY). Most costs have decreased over twelve years; however, medication costs are rising (by 4% annually, on-average), which suggests comorbidity burdens are too. As demand grows for expensive but potentially-better SARDs therapies, research to assess their impact on long-term comorbidity risk is needed.