Working to Investigate New Treatments and Evaluating Results; Comparison of Iloprost Therapy for Frostbite in Two Canadian Cities

Abstract

Background: Edmonton and Calgary are cities with populations of over 1 million. Both experience cold winter temperatures, making frostbite a common emergency departments (ED) presentation. Recently some EDs added iloprost for frostbite care. Iloprost is available in Canada via the Special Access Program. Its effectiveness for preventing amputations requires further investigation. The primary study objective compares amputation rates in patients with severe frostbite who did and did not receive Iloprost in two cities. Also assessed was iloprost adverse events.

Methods: This retrospective study assessed administrative data of patients ≥18 years treated in Edmonton and Calgary with grade 2-4 frostbite over a 3-year period. Abstracted data was categorized to include grade and amputation by digit, iloprost, and adverse medication events. Descriptive analysis and multivariable linear regression controlling for potential confounders was performed to identify predictors of amputation, for those receiving standard care (SC) or iloprost (IC).

Results: 257 patients met inclusion criteria (177/80 SC/IC). Mean age was 42.5(13.7SD), male sex n=208 (80.9%), comorbidities: houseless 140 (54.5%), active substance use/alcohol use disorder (175, 59.1%/ 69, 26.8%). Overall amputation rate for patients with grade 2 injury was similar between groups (SC 3/873.4%; IC 1/30 3.3%). For grade 3 injuries there was a higher proportion of amputations in SC (34/69, 69% vs IC 9/21, 42%; p = 0.042). For grade 4 injuries, there was no difference between groups (SC 17/21, 81%; IC 16/19, 84%; p = 0.787). Logistic regression suggests IC patients were less likely to have an amputation (p= 0.038, OR = 0.49, 95% CI = 0.25 - 0.96), and fewer digits amputated (p < 0.001, βST = -0.6, 95% CI = -0.91 - -0.3). Adverse effects of iloprost were reported in 49 (61.25%) patients, 44 (55%) having multiple adverse effects. Including (n): headache (25, 2.1%),Tachycardia >100 (14,13.1%), Nausea (13,12.1%), Hypotension (13, 12.1%), flushing (10, 9.3%), vomiting (7, 6.5%), myalgias (5, 4.7%), hypertension (4, 3.7%); Dizziness/abdominal pain/chills/palpitations (each n2, 1.9%); and chest pain, vein redness, tiredness, restless (each n1, 0.9%).

implications and lessons learned: Iloprost was associated with a lower likelihood and number of amputations for grade 2 and 3 frostbite injuries, but not in grade 4 injuries when compared to standard care.