Session Information
Date: Sunday, November 8, 2015
Title: Health Services Research Poster I: Diagnosis, Management and Treatment Strategies
Session Type: ACR Poster Session A
Session Time: 9:00AM-11:00AM
Background/Purpose:
Giant cell arteritis (GCA) is the most common form of adult vasculitis, but estimates of the healthcare costs of GCA are extremely scarce. We determined the incremental (extra) direct medical costs of a general population-based cohort of incident GCA for the first five years after diagnosis. We also assessed the changes in costs over calendar time (1996-2010).
Methods:
Data Source: Our administrative data captured all provincially-funded outpatient encounters and hospitalizations (1990-2010), and all dispensed medications (1995-2010), for ALL residents of the province of British Columbia, Canada.
Sample:We assembled a population-based cohort of all incident cases of GCA who satisfied the following criteria: a) ≥ 40 years of age; b) new diagnosis of GCA on at least one hospitalization or rheumatologist visit, or two non-rheumatologist visits, between January 1996 and December 2010; and c) use of oral glucocorticoids between 1 month before and 6 months after the second GCA visit (or first if from hospital or rheumatologist). Ten controls matched by age at diagnosis (±2 years), sex, and calendar year of diagnosis were selected for each case from the general population.
Cost Calculation: Costs for outpatient services and prescriptions were summed directly from billing data. Case-mix methodology was used for hospitalizations.
Statistical Analysis: We estimated the unadjusted incremental costs of GCA (difference in per-patient-year (PY) costs between cases and controls), then used generalized linear models to further adjust for socioeconomic status, urban/rural residence, and Charlson-Romano comorbidity index.
Results: We matched 797 incident GCA cases to 7,970 controls (72% female, mean age 76 ±9.2 years, median Charlson-Romano comorbidity index of 0). Unadjusted incremental costs of GCA for the first five years after diagnosis averaged $26,348 per-PY (2010 Canadian), with 78% from hospitalizations, 15% from outpatient, and 6% from medications. 59% of cases (vs. 26% of controls) were hospitalized during the first year after diagnosis, with GCA cases averaging 0.46 more admissions than controls (even after the index admission was excluded).
Following adjustment, 5-year costs for GCA cases were 1.9-times higher than matched controls (95% CI: 1.7-2.0, see Table). These incremental costs decreased over calendar time, even after inflation adjustment, averaging $41,113 per-PY for cases diagnosed over 1996-2002 (early period), and $19,033 per-PY for cases diagnosed over 2003-2010 (later period). Incremental hospitalization costs had the biggest change, decreasing by 61%, from $34,732/PY in the earlier period to $13,531/PY in the later
Conclusion:
The absolute costs of GCA have recently decreased, by 54%. Still, even after adjusting for pre-existing comorbidities, patients with newly-diagnosed GCA incur two-times more medical costs than age-matched individuals without GCA from the general population.
|
Adjusted Cost Ratios between GCA Cases and Matched Controls (95% CI) |
||||||
|
Year After GCA Diagnosis |
Total Over First Five Years |
|||||
|
1 |
2 |
3 |
4 |
5 |
||
|
N Cases Followed |
797 |
553 |
422 |
305 |
199 |
|
|
Mean Per-Patient-Year Outpatient Costs |
2.3 (2.1-2.4) |
1.8 (1.6-1.9) |
1.7 (1.6-1.9) |
1.6 (1.4-1.7) |
1.5 (1.3-1.7) |
1.7 (1.6-1.8) |
|
Mean Per-Patient-Year Inpatient Hospitalization Costs (amongst hospitalized individuals) |
1.1 (0.9-1.2) |
1.2 (1.0-1.5) |
1.3 (1.0-1.5) |
1.3 (1.0-1.6) |
1.4 (1.0-1.9) |
1.3 (1.2-1.4) |
|
Mean Per-Patient-Year Medication Costs |
1.4 (1.3-1.5) |
1.4 (1.3-1.5) |
1.5 (1.3-1.6) |
1.5 (1.3-1.7) |
1.4 (1.2-1.6) |
1.2 (1.1-1.4) |
|
Mean Per-Patient-Year Overall Costs |
2.4 (2.2-2.7) |
2.0 (1.8-2.2) |
2.0 (1.7-2.2) |
1.9 (1.6-2.2) |
1.9 (1.6-2.3) |
1.9 (1.7-2.0) |
|
Adjusted Mean Per-Patient-Year Incremental Utilization (95% CI) of GCA Cases |
||||||
|
Mean Per-Patient-Year Outpatient Encounters |
33.6 (31.5-35.8) |
18.8 (16.7-20.9) |
14.7 (12.2-17.2) |
13.5 (10.6-16.4) |
15.4 (11.7-19.1) |
55.9 (50.3-61.6) |
|
Mean Per-Patient-Year Inpatient Admissions (amongst hospitalized individuals) |
0.72 (0.39-1.06) |
0.46 (0.06-0.87) |
0.59 (0.16-1.03) |
0.77 (0.23-1.31) |
0.40 (-0.22-1.03) |
1.40 (1.05-1.76) |
|
Mean Per-Patient-Year Dispensed Prescriptions |
22.3 (17.0-28.3) |
27.9 (19.8-36.0) |
36.9 (27.3-46.5) |
35.6 (23.0-48.2) |
36.0 (18.6-53.4) |
65.5 (42.9-88.2) |
To cite this abstract in AMA style:
McCormick N, Marra C, Avina-Zubieta JA. Longitudinal, Incremental Direct Medical Costs of Giant Cell Arteritis for the First Five Years Following Diagnosis: A General Population-Based Cohort Study [abstract]. Arthritis Rheumatol. 2015; 67 (suppl 10). https://acrabstracts.org/abstract/longitudinal-incremental-direct-medical-costs-of-giant-cell-arteritis-for-the-first-five-years-following-diagnosis-a-general-population-based-cohort-study/. Accessed .« Back to 2015 ACR/ARHP Annual Meeting
ACR Meeting Abstracts - https://acrabstracts.org/abstract/longitudinal-incremental-direct-medical-costs-of-giant-cell-arteritis-for-the-first-five-years-following-diagnosis-a-general-population-based-cohort-study/