3.1 Epidemiology and access to diagnosis
We identified 64 C1-INH-HAE patients (39 female): 54 were type I (84.4%) and 10 type II (15.6%). Based on these results, the estimated minimal prevalence of HAE in Belarus is 1:148000. In 27 (42.2%) patients (8 of them were type II C1-INH-HAE) diagnosis was performed in the last 3 years. Thus, poor clinical awareness can contribute to the low diagnostic rate of HAE and may be a confounder in ascertaining true national prevalence. Geographical location of the patients in the country is shown in figure 1.
Median age of patients was 31.5 (min 2 – max 68 y), median age at diagnosis was 29.0 (min 1 – max 65 y). Median of C4 antigen was 0.08 g/l and was ≤50% of normal in 92.2% of patients. Median of antigenic C1-INH was 0.06 g/l and was ≤50% of normal in 100% of type 1 patients. Functional C1-NH was ≤ 40% of normal in 100% of patients. Median of C3 antigen was 1.04 g/l and was normal or slightly lower than normal range in 98.4% of patients. Mean levels of C1q were normal in 100% of patients. Data about mean age of patients, symptom’s onset, diagnosis and diagnostic delay, laboratory assessments are summarized in table 1. Eight patients had been diagnosed before the first symptoms appeared, based on SERPING1 gene analysis.
Thirty-two patients accepted to fill up a questionnaire to collect data about attacks and triggers. A total of 368 attacks were reported with an attacks mean/patient of 10 angioedema attacks annually: the number of attacks ranged from 1 to 41 episodes per year. According to questionnaires, attacks of angioedema were most often subcutaneous swellings (46% attacks), followed by abdominal edema (32%) and larynx (22%). In 72.4% of patients, triggering factors preceded angioedema. Symptoms were precipitated by stress in 26.4% of patients, infections in 16.1%, physical triggers in 87.3%, 36.2% of patients mention dental treatment, 6.5% - menstruation and 43.0% - seasonal changes.