Severe asthma—A population study perspective

Abstract

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.

Estimated burden of fungal infections in Sweden

“…There is likely some overlap between these patients as the most common mould to be sensitised to is Aspergillus fumigatus and many patients with ABPA are defined as having severe asthma. There is no direct estimate of ABPA prevalence from Sweden, but a recent paper shows on phenotype of severe asthma to be linked to A fumigatus sensitisation and at a frequency of 10%‐17% in severe asthmatics, depending on the definition of severe asthma (3.6% to 6.1%) . This estimate would put the SAFS prevalence at 2480 to 8296, substantially lower than our estimate, but still a significant problem.…”

“…There is no direct estimate of ABPA prevalence from Sweden, but a recent paper shows on phenotype of severe asthma to be linked to A fumigatus sensitisation and at a frequency of 10%-17% in severe asthmatics, depending on the definition of severe asthma (3.6% to 6.1%). 26 This estimate would put the SAFS prevalence at 2480 to 8296, substantially lower than our estimate, but still a significant problem. year with a prevalence of 99 cases (Table 1).…”

Uncontrolled asthma occurs in all GINA treatment steps and is associated with worse physical health – a report from the OLIN adult asthma cohort

“…As shown by us and others (7,16,37,38), women have a more severe asthma than men. In our study, women used more pharmacological treatment, had more exacerbations and healthcare visits than men.…”

“…N ¼ 1,006 subjects participated (71% of invited), of which n ¼ 830 had current asthma, and n ¼ 714 completed the Asthma Control Test (ACT) and were further studied. The clinical follow-up has been described in detail including inclusion criteria at study entry and non-responder analysis (16,18). The study was approved by the Regional Ethical Board at Umeå University, Sweden, and all participants provided written informed consent (2011/106-31).…”

“…However, if both adherence and inhalation technique is confirmed, and the patient still has poor asthma control, step-up treatment should be considered (11). About 5% of all asthmatics have severe asthma (15,16), and these are subjects that remain uncontrolled despite being stepped-up to high-dose treatment (treatment step 4 or 5), or subjects in need of high-dose treatment to prevent the disease from becoming uncontrolled (12,17).…”