Phase Specific Health Care Costs Associated with Giant Cell Arteritis in Ontario, Canada.

OBJECTIVE:To estimate the additional health care system costs associated with giant cell arteritis (GCA) in the year pre-diagnosis, post diagnosis, and over long-term follow up compared to individuals with similar demographics and comorbidities without GCA. METHODS:We performed a population-based study using health administrative data. Newly diagnosed cases of GCA (between 2002 and 2017 and ages 66 years and older) were identified using a validated algorithm and matched 1:6 to comparators using propensity scores. Follow up data was accrued until death, outmigration, or March 31, 2020. The costs associated with care were determined across three phases: the year before the diagnosis of GCA, the year after, and ongoing costs thereafter. RESULTS:The cohort consisted of 6,730 cases of GCA and 40,380 matched non-GCA comparators. The average age was 77 years (interquartile range 72-82) and 68.2% were female. A diagnosis of GCA was associated with an increased cost of $6,619.4 (95% CI 5,964.9 - 7274.0) per patient during the 1-year pre-diagnostic period; $12,150.3 (95% CI 11,233.1 - 13,067.6) per patient in the 1-year post-diagnostic phase, and $20,886.2 (95% CI 17,195.2 - 24,577.2) per patient during ongoing care for year 3 onwards. Increased costs were driven by inpatient hospitalizations, physician services, hospital outpatient clinic services, and emergency department visits. CONCLUSION:A diagnosis of GCA was associated with increased health care costs during all three phases of care. Given the substantial economic burden, strategies to reduce the healthcare utilization and costs associated with GCA are warranted.