Direct Medical Costs of Systemic Vasculitides

Background:

To estimate the direct medical costs in a population-based cohort of systemic vasculitides (VD)-polyarteritis nodosa, Wegener’s granulomatosis, giant cell arteritis, Takayasu’s disease, and Churg-Strauss syndrome-from the province of British Columbia (BC), Canada. Methods: Data sources: Our administrative data captured all provincally funded health services (outpatient visits, investigations and hospitalizations) and all prescriptions from 1996-2007 (regardless of funding source). Study population: A population-based cohort of VD cases was identified using the following algorithm: (a)≥2 ICD codes for VD ≥ 2 months apart but within a 2-year period by any non-rheumatologist physician (b)≥1 ICD code for VD by a rheumatologist, or (c)≥1 hospitalization diagnostic code of VD.  To improve specificity, we excluded individuals with at least 2 visits ≥ 2 months apart subsequent to the 1st VD visit (2nd for a non-rheumatologist) with diagnoses of other inflammatory arthritides, and those where a VD diagnosis by a non-rheumatologist was unconfirmed when seen by a rheumatologist. Cost calculation: Costs for medical services and prescriptions were summed directly from paid claims.  Case-mix methodology was used for hospitalizations. Costs are reported in 2007 Canadian dollars. Results: We identified 1680 VD cases contributing 4763 patient-years (PY). Direct medical costs over 12 years totalled $75,697,339 with $14,985,736 (20%) from outpatient costs and $50,964,228 (67%) from hospitalizations. Medication costs were $9,747,374 (13%). Over 12 years, after inflation adjustments, mean annual per-PY utilization and expenditures decreased for two components: hospital expenditures by 60% (from $15,596 to $6179), with the mean number of hospitalizations decreasing 54% (from 1.85 in 1996 to 0.86 per-PY in 2007), and outpatient costs by 32% (from $3687 to $2512 per-PY).  The mean number of outpatient encounters/year decreased 21% (from 53 in 1996 to 42 in 2007), with the biggest drops in visits and spending after 2003.  Conversely, medications had a mean per-PY cost increase of 59% (from $1426 in 1996 to $2272 in 2007), rising the most from 1998-2003, and their proportion of costs tripled, making up 7% of total costs in 1996 and 21% in 2007. Conclusions: For a small number of cases, VD account for a substantial health care burden at the population level, with the average patient having 42 outpatient visits and 54 prescriptions, and costing $10,964, in 2007.  While some per-patient direct medical costs have decreased over 12 years, drug spending in VD continues to rise.