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Summary Background Severe asthma is a considerable challenge for patients, health‐care professionals and society. Few studies have estimated the prevalence of severe asthma according to modern definitions of which none based on a population study. Objective To describe characteristics and estimate the prevalence of severe asthma in a large adult population‐based asthma cohort followed for 10‐28 years. Methods N = 1006 subjects with asthma participated in a follow‐up during 2012‐14, when 830 (mean age 59 years, 56% women) still had current asthma. Severe asthma was defined according to three internationally well‐known criteria: the ATS workshop definition from 2000 used in the US Severe Asthma Research Programme (SARP), the 2014 ATS/ERS Task force definition and the GINA 2017. All subjects with severe asthma according to any of these criteria were undergoing respiratory specialist care and were also contacted by telephone to verify treatment adherence. Results The prevalence of severe asthma according to the three definitions was 3.6% (US SARP), 4.8% (ERS/ATS Taskforce), and 6.1% (GINA) among subjects with current asthma. Although all were using high ICS doses and other maintenance treatment, >90% did not have controlled asthma according to the asthma control test. Severe asthma was related to age >50 years, nasal polyposis, impaired lung function, sensitization to aspergillus, and tended to be more common in women. Further, neutrophils in blood significantly discriminated severe asthma from other asthma. Conclusions and Clinical Relevance Severe asthma differed significantly from other asthma in terms of demographic, clinical and inflammatory characteristics, results suggesting possibilities for improved treatment regimens of severe asthma. The prevalence of severe asthma in this asthma cohort was 4%‐6%, corresponding to approximately 0.5% of the general population.

Changes in both prevalence and risk factor patterns of COPD were observed between surveys. Following a continuing decrease in smoking habits over several decades, a decrease in the prevalence of moderate to severe COPD was observed from 1994 to 2009 in northern Sweden.

Quality of life (QOL) is a concept with no generally accepted definition. Most clinical studies have had an individual approach where demographic and socio-economic population aspects have not been considered. QOL has hardly ever been used in studies of children. In this study QOL is defined as the essential resources of a child population, expressed in external, inter-personal and personal conditions. Both objective conditions and the corresponding subjective perceptions are included. A model for an empirical application is demonstrated on a random sample of 15,000 children in the five Nordic countries. The data were collected in a questionnaire mailed to the families of the children. The QOL was analysed in a normative way, where a base value was defined for each variable and the conditions of the children were compared to a Nordic standard for children's QOL. The results showed that children in the Nordic countries have a high QOL. The differences between the countries were rather small. Children in Sweden had the highest QOL, closely followed by children in Denmark and Norway, while children in Finland were in an intermediate position and the Icelandic children had the lowest QOL, mainly due to a lower level of satisfaction. This study can be considered as a base line study which later can be used in studies of time trends or in comparisons of groups of children such as children with special needs.