A Population-based Investigation of Asthma in the Telemark Region of Norway

Respiratory conditions impose an enormous burden on the individual and the society. According to the WHO World Health Report 2000, the top five respiratory diseases - including asthma and COPD - account for 17% of all deaths and 13% of all Disability-Adjusted Life Years (DALYs). Obstructive lung diseases are among the most common chronic diseases in working-aged populations affecting ~40 million individuals in Europe. The greatest economic burden of respiratory diseases on health services and lost production in the EU is due to COPD and asthma, at about €20 billion each for healthcare and €25 billion and €15 billion, respectively, for lost production.

For Norway, there are no estimates of asthma prevalence for the country as a whole, but 80/1000 women and 55/1000 men used asthma medication in 2013 according to the national prescription register. Estimated annual deaths in Norway due to COPD were 4070 in 2015, which is 30% higher than for lung cancer. Unfortunately, a substantial proportion of patients are still difficult to treat. This underlines the need for better primary prevention and more knowledge regarding causes and exacerbating factors.

Several risk factors for chronic respiratory diseases are identified, most important tobacco smoke, closely followed by air pollution and occupational exposure. However, according to recent reviews there is a lack of understanding regarding environmental risk factors and mechanisms of how these affect respiratory health, the importance of biological markers and comorbidity, and of socioeconomic risk factors. Moreover, there is a need for assessment of interactions between risk factors and between the individual and the environment.

Telemark has a high proportion of craft- and industrial workers providing exposure contrasts. Furthermore, the use of medication against respiratory diseases and the rate of sick leave are higher in Telemark than elsewhere in Norway. Moreover, the county has a high rate of disability. There are previous studies from other parts of Norway, which have estimated the occurrence of respiratory diseases and provided valuable knowledge regarding some risk factors. However, these studies use crude measures of self-reported exposure and do not provide sufficient information on how to target intervention and implement effective prevention. In contrast to the Telemark study, these studies have not included register data or advanced modelling of environmental exposure.