A subgroup analysis of all 57 patients who had had a death in the family showed that these were type I HAE in all but one case, and there was a slightly longer diagnostic delay of 12 years in this group compared to the overall diagnostic delay of 10 years. This appears to argue against a death in the family resulting in a clear reduction in diagnostic delay for other family members. When analysed separately, the average annual frequency of swellings in families with one or more deaths was: peripheral 14, abdominal two and airway 0·6. However, drawing firm conclusions from these frequencies is difficult,

given the small size of the group. There was a minor increase in airway swellings above the overall average, but it is Temsirolimus clinical trial likely that factors other than the specific DAPT datasheet SERPING1 mutations modify swelling frequency, severity and site. Data from two patients’ swellings in whom peripheral swellings were described as ‘too many’ rather than giving a numerical

value were excluded. Acquired angioedema (AAE) accounted for 6% of cases (n = 19) of angioedema. The average age of onset was 68 years, with equal numbers of males and females. The underlying diagnoses, where available, were haematological [chronic lymphocytic leukaemia (CLL) in three cases, and the following diagnoses were all reported in individual patients: non-Hodgkin lymphoma (NHL), B cell lymphoma, marginal zone lymphoma (MZL), follicular lymphoma, Waldenström's macroglobulinaemia and an immunoglobulin (Ig)M kappa paraprotein, in order of frequency]. There was no report of AAE associated with connective tissue or autoimmune disease. Although the numbers of patients reported with acquired angioedema is small (n = 19), there was the suggestion of a difference in the frequency of swellings compared with hereditary

angioedema, with mean values of peripheral 0·7, abdominal one and airway 0·9 per patient many per year. The overall frequency of swellings appears lower – particularly peripheral and abdominal – with a more even spread of sites and the possibility that airway swellings occur at a higher rate (60% higher than HAE). Any differences should, however, be interpreted with caution due to the smaller numbers of patients and clear variability between individuals. In addition, 45% of AAE patients did not have a swelling during the previous year. Anti-C1 esterase inhibitor antibodies were not tested routinely and reported as positive in only two patients, perhaps reflecting the lack of availability of this assay at the time of data collection. Thirteen patients were taking long-term prophylaxis: six tranexamic acid, five danazol, one on both tranexamic acid and danazol and one on prophylactic C1INH. This study describes the first National Audit of patients with hereditary and acquired C1 inhibitor deficiency in the United Kingdom, capturing detailed information from 376 patients attending 14 centres in England, Scotland and Wales.