Hereditary angioedema is a rare but serious condition, in which affected patients suffer a significant burden of disease, similar to that of severe asthma or Crohn’s disease . Additionally, patients with HAE deal with the uncertainties and unpredictable nature of episodic attacks of angioedema.
Few studies have evaluated the quality of life in patients with HAE [3, 9]. In this study, Canadian patients exhibited an impaired quality of life, as measured by the standardized SF-36v2, particularly in the domains of general health, bodily pain and vitality. In previous data, patients with HAE reported decreased mental and physical health as well as social effects compared to a normal population, in keeping with our study of Canadian patients [3, 9, 10].
In both the study by Gomide  and our study, the SF-36 subscales with the lowest median values were General Health, Bodily Perception and Vitality (40, 52, and 60 respectively for the Gomide  study and 62.0, 74.0, and 62.5 respectively for our study). The median value for the SF subscale differed between the two studies (median value of 50 vs. 100). A more recent Danish study by Aabom et al. showed mean SF-36v2 scores corresponding with population norms, likely explained by differences in treatment options and access to around the clock counseling for Danish patients .
The high Cronbach’s alpha for all SF-36 scales indicates a high internal consistency. However, the high alpha coefficients observed might be partly due to the ceiling effects observed in some subscales (mainly RE and SF, but also PF and RP). These ceiling effects could be related to a low sensitivity of these subscales or to nearly no affection of these subscales in Canadian HAE patients.
Health-related quality of life questionnaires are developed to evaluate individual patient health status, assess the cost-effectiveness of an intervention or treatment, and to monitor disease burden. Several questionnaires have been developed to evaluate health related quality of life and help establish resource allocation . The standardized SF-36v2 questionnaire can be a useful tool in the assessment of quality of life in patients with HAE, which allows comparison to other diseases, however a need exists for disease-specific surveys, to serve as a more precise indicator of disease burden. Disease-specific surveys can serve as a point of comparison with generic questionnaires and further evaluate particular aspects of disease severity. A specific HAE QOL questionnaire has been developed in Spain and translated and validated in other countries [13, 14].