This trial is active, not recruiting.

Conditions obstructive lung diseases, respiratory symptoms, inflammation
Sponsor Sykehuset Telemark
Collaborator Oslo University Hospital
Start date February 2014
End date December 2015
Trial size 2000 participants
Trial identifier NCT02073708, 1665


One out of ten adults and up to 20 % of children in Northern Europe are diagnosed with asthma. Patients with onset of disease in childhood and patients with adult-onset asthma have in common that their symptoms can be aggravated by exposures in the workplace. Work exacerbated asthma (WEA) is defined as worsening of asthma due to conditions at work and is common with a median prevalence of 22 %. However, additional research is needed to improve the understanding of the risk factors, mechanisms and outcomes of WEA. Studies of difference in response to exposures between subgroups of asthma patients may provide new insight also into the phenotypic heterogeneity of asthma.

The primary aim of the study is to estimate the incidence rate of asthma in relation to age, sex, socioeconomic factors and occupational exposures in a prospective study. Recently, data on respiratory symptoms and physician diagnosed asthma has been collected from 16.300 inhabitants of Telemark County (baseline study). A random sample from the baseline sample of 1000 asthma cases and 1000 controls will be asked to participate in a medical examination in which blood pressure, lung function and Fraction of exhaled nitric oxide (FeNO) will be measured. In addition, blood samples will be collected form analysis of inflammatory markers and gene sequencing. The case-control study will be repeated after five years and ten years, if founded (5- and 10-year follow-up).

United States No locations recruiting
Other Countries No locations recruiting

Study Design

Observational model case control
Time perspective prospective

Primary Outcomes

The occurence of work exacerbated asthma in different asthma phenotypes, and the association to specific occupational and environmental exposures and comorbidity
time frame: two years

Secondary Outcomes

Risk factors for the occurence of asthma symptoms in subjects with asthma symptoms but no asthma diagnosis
time frame: two years
Differences in lung function, FeNO and inflammatory markers in blood in asthma patients and the association of these changes to specific occupational and environmental exposures.
time frame: two years

Eligibility Criteria

Male or female participants from 16 years up to 50 years old.

Inclusion Criteria: - Physician diagnosed asthma - Controls without respiratory symptoms Exclusion Criteria: - Subjects with asthma symptoms but no asthma diagnosis - Chronic obstructive pulmonary disease

Additional Information

Official title A Population-based Investigation of Asthma in the Telemark Region of Norway
Principal investigator Anne Kristin Møller Fell, PhD
Description Hypotheses and choice of methods: 1. In a large random sample of the population of Telemark the investigators have estimated the occurrence of both child-onset and adult-onset of physician diagnosed asthma. Childhood asthma is defined as persons with a history of physician-diagnosed asthma at age > 18 years. The case-control study allows the identification of specific exposures that may be associated with an increased or decreased occurrence of asthma and exacerbation of disease and gives the opportunity to compare differences in these outcomes between those with child-onset and adult-onset of asthma. Previous studies have mainly used crude measures of self-reported exposure to biological dust, mineral dust, gas or fumes when assessing occupational exposure. This leads to a loss in precision when characterizing exposure. In the case-control study all asthmatics and two controls will receive a comprehensive questionnaire by mail and be asked to answer additional questions regarding occupational exposure, nutrition and physical activity. On the basis of the questionnaires, a job exposure matrix (JEM) will be established for each participant. For those who participate in the medical consultation, the questionnaires and the JEMs will be updated and reviewed together with the patient through structural interviews. An occupational hygienist will assess all occupations as being exposed, not exposed or "uncertain or low exposed" to validate the use of JEM and to ensure that the participants are correctly classified. The JEM is based on the Nordic matrix (NJEM) [1] with some changes that are more adaptable to exposure conditions in Telemark, which is one of the main onshore industrial centers in Norway. This will provide comprehensive exposure information. The use of a JEM is expected also to reduce risk of information bias, specifically biased reporting of exposure. Research indicates that participants with respiratory symptoms can over-state their exposure and those without symptoms can understate their exposure, biasing effect estimates away from the null [2]. The use of a JEM provides more objective and less biased exposure estimates than self-reports alone [3]. This will allow a better identification of groups at risk. Whereas the medical examinations will allow the assessment of severity of disease and provide the basis for studies of mechanisms of WEA. 2. In the case-control study lung function, FeNO and levels of inflammatory markers in blood and analysis of heritability through gene sequencing will be performed. These outcomes will be compared in patients with child- and adult-onset asthma and with controls. More than 100 asthma candidate genes have been identified by genome wide association studies (GWAS). However, the causality of the variants detected by GWAS is questionable and many of the asthma candidate genes have not been replicated. This may in part be explained by the fact that only common genetic variants are detected by GWAS. Another possible explanation is that any signal has been diluted by phenotypic heterogeneity. Asthma is known as a heterogenic disease, and lack of clinical description of included asthma cases in genetic studies is recognized. The investigators will meet this challenge by performing a medical examination of the participants in combination with novel genetic methods (Next-Generation gene Sequencing). Rare variants can be detected by Next-Generation gene Sequencing (NGS) of the asthma candidate genes and may thus explain some of the "missing heritability" of asthma. A panel of asthma candidate genes will be designed, and NGS of exons and flanking intron sequences will be performed. 3. The consumption of health care services associated with asthma will be estimated through collection of information from the case-control study participants' in relation to the use of health services, hospital admissions, consultations, surgery, medication, etc. The regional ethics committee has given permission to connect to national registers for disability, sick leave and unemployment to make calculations, of disability and sick leave. The investigators will study asthma-related sick leave and disability in relation to occupation and analyze the data in strata of gender, age, ethnicity, different levels of education and occupations. The participants will finn-inn a questionnaire regarding health related quality of life (HRQoL) at baseline of the case control and at pre-defined time intervals. Further, the investigators will measure the occurrence of cardiovascular diseases, fatigue, chronic fatigue, anxiety and depression since these variables are known to influence the patients' HRQoL. The study will provide a unique opportunity to report how patients with asthma experience treatment and how they cope with every-day life. Further, comparison of HRQoL will be made between patients with work-related asthma and those without work-relation. The data analysis allows also the identification of subgroups with poor perceived health and help to guide interventions to improve their situation.
Trial information was received from ClinicalTrials.gov and was last updated in April 2016.
Information provided to ClinicalTrials.gov by Sykehuset Telemark.