Treatment of Vascular Anomalies With Sirolimus: Characterizing Practice Patterns of US Specialist Clinicians

Sirolimus is a mainstay medical therapy for vascular anomalies (VAs). However, there is limited guidance on managing sirolimus.

We sought to characterize the practice patterns of clinicians who prescribe sirolimus to identify best practices or areas of disagreement warranting future investigation.

We conducted standardized interviews with 92 US clinicians who prescribe sirolimus to patients with VAs. We performed descriptive statistics of clinicians' responses.

We found wide variation in sirolimus practices. Clinicians reported numerous dosing strategies. The upper end of target goal troughs ranged from 6 to 15 ng/mL, with some clinicians targeting as low as 4-6 ng/mL and others as high as 10-15 ng/mL. Clinicians were split on whether they always, sometimes, or never administered pneumocystis prophylaxis. They were similarly divided on how they administered live-attenuated vaccines, with some forgoing vaccination indefinitely, some administering with specific measures, and others administering without precautionary measures. Fever management also varied. While many encouraged primary care evaluation, nearly 20% mandated emergency department visits. A sizeable minority obtained blood cultures and administered empiric antibiotics to all patients with fevers. Lastly, peri-procedural management of sirolimus varied. Half of the clinicians held sirolimus for major procedures, and 14% held sirolimus for all procedures, including sclerotherapy.

Despite more than 15 years of data on the efficacy of sirolimus, we identified wide variation in how clinicians prescribe and manage sirolimus for patients with VAs. Future work is needed to generate data and develop evidence-based guidelines for the management of sirolimus to ensure safe and appropriate care.