Quantifying the burden of systemic sclerosis: A data linkage study.

Abstract

Introduction: Systemic sclerosis (SSc) is an incurable multi-organ autoimmune disease with substantial morbidity and mortality. Due to varied clinical manifestations, patients with SSc are usually on multiple medications and require frequent hospitalization and consultation with specialists and allied health from a broad range of disciplines. We hypothesize that the cost of healthcare in SSc is substantial, and sought to quantify this health service utilization and associated cost among Australian SSc patients. Material(s) and Method(s): Health service use was captured by means of data linkage. Data for all Victorian SSc patients enrolled in the Australian Scleroderma Cohort Study (ASCS) (n=531) between 2011-2015 were linked with the Victorian hospital admissions and emergency presentations data sets and the Medicare Benefits Schedule (MBS), which contains all government subsidized ambulatory care services. Hospitalization cost was calculated based on the financial year of admission, admission diagnosis, length of stay and the corresponding value of each admission unit for that financial year. Ambulatory care cost was based on the MBS fee payable by the Australian government for each service, and medication cost was estimated from the Pharmaceutical Benefits Scheme (PBS). Cost was extrapolated to all Australian SSc patients based on SSc prevalence (21.1 per 100,000) and population data (Australian population 24,304,682 in 2015). Result(s): Total health service utilization cost to the Australian government extrapolated to all Australian SSc patients between 2011-2015 amounted to AUD$298,065,737.15 (USD$219,376,382.55), which is an average annual cost of AUD$59,613,147.43 (USD$43,875,276.51) and annual cost per patient of AUD$11,622.76 (USD$8,554.35). Hospital costs, including inpatient hospitalization and emergency department presentations, accounted for the majority (44.5%) of these costs, followed by medication cost (31.1%) and ambulatory care cost (24.4%). Determinants of hospitaliza-tion included older age at SSc onset (OR 1.02, p=0.05), pulmonary arterial hypertension (PAH) (OR 2.1, p=0.02), digital ulcers (OR 1.6, p=0.04), gastrointestinal involvement (OR 1.7, p=0.01), hand dysfunction (OR 1.7, p=0.01) and stroke (OR 2.7, p=0.03). Conclusion(s): Our study provides the most comprehensive assessment of healthcare utilization and its determinants in SSc to date, and highlights the substantial direct cost of this disease despite its low prevalence. Linkage of clinical and administrative data sets allows the collection of information regarding direct costs of healthcare use in SSc without recall bias. These findings can be used to guide resource allocation and the development of tailored policies to improve patient outcomes.