Hydralazine Use and Risk of Vasculitis.

Hydralazine use was associated with a statistically higher risk of vasculitis compared to ACE or ARB use in the primary analysis.

• Hydralazine group: 328 vasculitis events (0.8%); ACE or ARB group: 2712 vasculitis events (0.5%)
• Absolute risk difference of 0.3 percentage points
• Hazard ratio of 1.19 (95% CI, 1.04–1.37)
• Overlap-weighted Cox proportional hazards regression was used
• Vasculitis diagnosis was ascertained using ICD-10 codes

The association between hydralazine use and vasculitis was no longer statistically significant when accounting for the competing risk of death.

• Results were 'no longer significant when accounting for the competing risk of death'
• This suggests mortality may be a substantial competing event in this older adult population
• The mean age of the cohort was 73.0 (SD 7.2) years

The study cohort included 583,136 eligible adults from Ontario, Canada, newly prescribed either hydralazine or an ACE/ARB between 2008 and 2021.

• 40,748 individuals were dispensed hydralazine and 542,388 were dispensed an ACE or ARB
• Mean age was 73.0 (SD 7.2) years; 51,827 (55.2%) were female
• Study included adults 66 years or older
• Population-based retrospective cohort design using Ontario health administrative data
• Data analysis was performed from May to August 2025

Despite multiple published case reports and case series linking hydralazine to ANCA-associated vasculitis, vasculitis associated with hydralazine was rare in this large population-based study.

• Only 328 vasculitis events occurred among 40,748 hydralazine users (0.8%)
• The authors note hydralazine is 'a selectively used cardiovascular medication with case reports and case series demonstrating an association between the use of hydralazine and antineutrophil cytoplasmic antibody-associated vasculitis'
• The authors conclude that 'use of hydralazine is unlikely to be associated with a clinically meaningful increased risk of vasculitis'