Methods: This is an ongoing, prospective, multi-center, observational study (NCT01541423). The analysis included data from patients enrolled for ≥3 months between May 2012 and May 2015 and who received C1 INH for ≥1 month.
Results: Data from 45 patients were categorized according to the frequency of doses received: intensified routine prophylaxis (every 1 or 2 days; n=14 [31.1%]), routine prophylaxis (every 3 or 4 days; n=39 [86.7%]), and prolonged-interval prophylaxis (every 5 to 7 days; n=15 [33.3%]). Due to an individual and adaptive treatment approach, 42.2% of patients received more than one dose regimen. An interval of ≥8 days was considered an interruption in dosing; patients had a median of 5.5 dose interruptions. Patients received intensified, routine, and prolonged-interval regimens for a median of 20.5, 197.0, and 47.0 days, respectively. The median attack frequency was 4.8, 1.4, and 4.0 attacks per month. Overall, 69.7% of attacks occurred on the day of the next expected dose; 45.7% of these were "mild".
Conclusions: In the real-world setting, patients decreased the dosing interval of C1 INH during periods when they were having more frequent attacks and frequently interrupted their dosing regimen. Attacks occurred most often on the day the next dose was due, suggesting that delaying a prophylaxis dose, even by only a few hours, may leave patients vulnerable to an attack.