West Sweden Asthma Study – clinical epidemiology on asthma and allergies

Background

Asthma together with allergic diseases are among the great diseases of our time and constitute the largest disease group among children and adults up to middle age. It is estimated that 300-400 million people worldwide have asthma. The prevalence of asthma has increased significantly in many parts of the world. For the dimension of care, it is important to know about how the prevalence of major diseases such as asthma changes over time. Changed environmental exposure and lifestyle can be important for incidence, disease progression, remission and relapse.

Aims

The overall purpose of the study is an epidemiological update on the prevalence, incidence, remission and relapse of asthma as well as the factors that correlate with these. Both cross-sectional data and longitudinal data are used.

Results

The research project was started in 2008 and has resulted in nearly 100 scientific publications over the years. Many different researchers from different disciplines have been involved.

Among our recent results, we have been able to show that the prevalence of asthma has increased slightly in 2008-2016 and is now just over 11%, the largest increase seen in the 16-25 age group. The prevalence of respiratory symptoms also increased in Västra Götaland during this time period. The occurrence of allergic rhinitis was the most common symptom and it also showed the greatest increase. Preliminary data show that the incidence of asthma remains at approximately 2/1000 / year and co-varies with female sex and prevalence of allergic rhinitis.

As the publications are numerous, here follows a brief summary of previous results:

Although a five-fold increase in the use of asthma medicine has taken place since the early 1990s, and that the use of inhaled steroids has increased from 1.5 to 7.7% in the population, the adherence to asthma medication has been shown to be low. There is potential for improvement in asthma care in order to improve the adherence of asthmatics in general and thereby achieve asthma control.

By using a few questions in the 2008 postal survey, a group of asthmatics with multiple symptoms despite use asthma medication could be identified; these made up 2% of the population and 25% of all asthmatics. The definition was associated with clinical signs of more severe disease and not dependent on inferior adherence. By defining symptoms indicative of severe asthma and examining these phenotypic signs, we were able to show that at least 1/3 of all people with asthma have at least one sign of severe disease and the variation is great. The prevalence of the phenotype with asthma-COPD overlap accounted for 3% of the population, and these have poorer lung function and more clinical symptoms than those with only asthma or COPD.

Smoking has a negative impact on the respiratory tract already after a few years, which is especially evident among young women who not only smoke more than young men, they also have an earlier smoking debut and a higher incidence of bronchitis symptoms. In collaboration with the OLIN studies, we have shown that the use of e-cigarettes is most common among smokers, and those who use both regular cigarettes and e-cigarettes have a higher incidence of respiratory symptoms.

Regarding rhinitis, we have been able to show that the protective effect of growing up on a farm on the occurrence of rhinitis, previously shown in studies in children, remains throughout life. In the case of allergic sensitization, in particular, pollen sensitization has increased, as has multisensitization, where the latter is strongly correlated with asthma. Food hypersensitivity shows a rising trend among adults, however, the correlation with specific IgE, which would indicate allergy, is generally low. WSAS has many uses and selected groups of participants have been included in mechanistic studies and the random selection has served as a control material for studies of a Swedish normal equation for lung function, scoliosis, esophageal atresia and as well as severe wheezes in childhood.

Group members currently working on the project

Eivind Borna

Hannu Kankaanranta

Bo Lundbäck

Linda Ekerljung

Background

There is limited data on the prevalence and characteristics of severe asthma in the population. and we need to generate more knowledge about prevalence, clinical characteristics and treatment and the implications of having severe asthma. Severe asthma consists of several different phenotypes and how these should be treated is partly unclear. Knowledge of the development of incidence and severity of asthma is of great importance to society. The study provides a unique opportunity to gain knowledge from a population based sample, knowledge that is limited today. Severe asthma leads to frequent health care visits and accounts for most of the health economic costs of asthma. To be able to develop interventions and reduce the burden of illness for people with severe asthma, further research is needed that focuses on clinical and health psychological aspects.

Aims

The study focuses on issues of severe asthma in an epidemiological setting. Particular focus will be on: prevalence and demographics of severe asthma according to current definitions; identification of impactable risk factors; the occurrence of anxiety and depression and its impact on health-related quality of life; knowledge about how people with severe asthma manage their illness and what support they need to reach their treatment goals.

Results

Preliminary data from our cohort show that the prevalence of severe asthma in the population is 0.5-1%. These individuals have more symptoms, poorer lung function, and poorer asthma control than those with other types of asthma, despite using more asthma medications.

Group members working on the project

Lina Rönnebjerg

Hannu Kankaanranta

Bo Lundbäck

Linda Ekerljung

Background

An intriguing sex-related differences in asthma has been observed for decades, whereby asthma is more common in boys than in girls during early childhood, but becomes more common and more severe starting from puberty and into adulthood. While the cause of these gender-related differences are not fully understood, the female sex hormones are thought to largely play a role. The female’s life is characterized by several hormonal transition points - menarche, menstruation, pregnancy, and menopause – and each of these has been linked to asthma. The use of hormonal contraception during the reproductive life and hormone therapies during menopause have also been hypothesized to play a role in asthma in women. Although several studies have been performed during the last four decades to understand the role of the female sex hormones in the pathogenesis of asthma, the overall literature remains conflicting.

Aims

Within the West Sweden Asthma Study, our overarching aim is to definitively elucidate on the role of female sex steroids in the pathogenesis and clinical manifestation of asthma in women. In addressing this question, our investigations cover clinical and genetic epidemiology, from where we aim to undertake mechanistic studies to try to uncover the biological processes through which sex steroids influence asthma in women.

Group members working on the project

Guo-Qiang Zhang

Hannu Kankaanranta

Bo Lundbäck

Bright Nwaru

Background

Current research advances have shown that obstructive airway diseases are heterogeneous conditions, both in their clinical manifestation and disease severity. This has persuaded current recognition that optimal treatment of these diseases can be attained when treatments are individualized. However, achieving an individual-tailored treatment requires a clear understanding of the phenotypic characteristics of each patient. Disease phenotyping will: (1) contribute to better understanding of the underlying disease pathogenesis; and (2) provide a clinical support for attaining individual tailored treatment. Computational approaches that use high-level computer programming have been particularly useful in uncovering the different phenotypes of human diseases.

Aims

In this project, based on the West Sweden Asthma Study and in collaboration with the Obstructive Lung Disease in Northern Sweden, we are using novel computational methods to identify distinct phenotypes of obstructive airway diseases in adults. We then investigate the impact of environmental and genetic factors on the derived phenotypes, as well as the healthcare use trajectories and co-morbidity patterns of the derived phenotypes.

Group members working on the project

Muwada Bashir

Rani Basna

Bo Lundbäck

Hannu Kankaaranta

Bright Nwaru

Background

Research in airway diseases in Nordic countries has often been done in fragments. The West Sweden Asthma Study (WSAS) and the Obstructive Lung Disease in Northern Sweden (OLIN) studies represent some of the largest population-representative longitudinal cohort studies in obstructive airway diseases in Europe, with enormous amount of data across demographic, clinical, and biological parameters. These data are now being linked to Swedish national registers, thus providing the opportunity to undertake important investigations in obstructive airway diseases.

Aims

STELLAR aims to build a robust long-term multidisciplinary research environment that capitalizes on the extensive longitudinal data being generated from WSAS and OLIN, with linkage to the Swedish national registers, in order to catalyze novel epidemiological studies and increase capacity in undertaking respiratory research in Sweden. By harnessing cohort-register linked data, we will create a platform that will (1) minimize the fragmented nature of respiratory epidemiology research in Sweden and pursue more collaborative approach that enables cross-cohort data pooling; (2) bridge the gap between respiratory scientists and the lay population and stakeholders in order to continuously draw patients and lay audience closer to scientific research activities in Sweden; and (3) develop an innovative platform for continuous training of the next-generation of respiratory epidemiology researchers. Whilst initially focusing on bringing together WSAS and OLIN, our overarching goal is to establish a nation-wide platform that brings together other cohort-register linked studies in respiratory research across Sweden.

Group members working on the project

Rani Basna

Linda Ekerljung

Bo Lundbäck

Hannu Kankaanranta

Bright Nwaru

Background

Histamine intolerance (HIT) has been reported for several decades, but despite this, the knowledge of background and treatment is unclear, the exact prevalence is unknown but is estimated at about 1%. HIT's pathophysiology is unclear but is believed to be a non-IgE mediated food hypersensitivity. Histamine and other bioactive amines are found in some foods and furthermore certain foods can release the body's own histamine. There is a relatively weak scientific evidence that hypersensitivity is partly due to decreased activity of diamine oxidase (DAO), which is the major enzyme involved in histamine degradation. There is no knowledge of how to clinically use and evaluate DAO in patients. Lactose intolerance is characterized by the complete or partially limited ability to break down the carbohydrate lactose that is found naturally in dairy products such as milk, fil, yogurt, cream. Recent years' research has defined lactose as carbohydrate with increased fermentation capacity in people with functional gastrointestinal disorders, so-called IBS. The most defined cause of hypersensitivity to gluten-containing cereals is celiac disease. Celiac disease should be diagnosed in a doctor by checking antibodies in the blood and in most cases doing a small bowel biopsy. It has been discussed that diagnosis without biopsy can be made if there is a high concentration of transglutaminase antibodies. The number who choose gluten from the diet in the Nordic countries has limited knowledge of.

Aims

The study aims to determine the normal interval for DAO, if there is a pathological reference area and to identify factors that may influence DAO activity. The study is of clinical significance as the number of questions and referrals around suspected histamine hypersensitivity increases in adult allergy and in the community and on social media. However, knowledge about the problem of this hypersensitivity is very limited. Furthermore, the study aims to measure the prevalence of self- and physician-diagnosed gluten and lactose intolerance in the population, describe which symptom picture they suffer based on their self-diagnosis and determine if there is a link to other food sensitivities and allergies?

Group members working on the project

Adina Weisheit

Bright Nwaru

Linda Ekerljung

Collaboration with the Allergy Clinic at Sahlgrenska University Hospital chief physician Monica Arvidsson and dietitian Jenny van Odjik