Doctoral dissertation

Minna Tommola: Adult-onset Asthma and Smoking

Minna Tommola
Smokers and patients with smoking history have generally been excluded from previous studies on asthma, and therefore relatively little is known about the effect of smoking on asthma. Previous population-based and registry studies have suggested negative effects of smoking on asthma, but the results have been inconsistent.

Asthma-chronic obstructive pulmonary disease overlap (ACO) has recently been recognized and included in guidelines but remained rarely studied. Identification of ACO has nevertheless been considered important, because of the modern, personalized therapy options. The diagnostic criteria for ACO are not confirmed, but some criteria have been previously suggested.

The aim of the study of M.D. Minna Tommola was to evaluate the effect of smoking on asthma and to investigate the differences between asthma and ACO. Further aims were to evaluate the usability and validity of the proposed criteria for ACO, and to investigate the role of occupational exposures in developing of ACO.

The study investigated adult-onset asthma patients in the Seinäjoki Adult Asthma Study (SAAS) but also data on patients entitled to asthma medication reimbursement in Finland, and data on Cohort for Reality and Evolution of Adult Asthma (COREA) cohort were used in some analyses.

The Seinäjoki Adult Asthma Study is a real-life cohort of patients with asthma diagnosed at adult age. The diagnosis was based on objective lung function measurements and respiratory specialist evaluation and the guidelines were followed. Smokers were included in the SAAS cohort.

Smoking history of ≥ 10 pack-years was associated with increased loss of lung function in adult-onset asthma. The accelerated loss of lung function continued even after smoking had stopped if 10 pack-years had been reached. The pack-year history was dose-dependently associated with increased disease burden and multimorbidity when measured by hospitalizations, symptoms and comorbidities.

A pack-year history of ≥ 20 pack-years was independent of other factors associated with hospitalizations for any respiratory reason. ACO differed from asthma by showing lower diffusing capacity, higher blood neutrophil and IL-6 levels and higher remaining bronchial reversibility.

Differences were also found between ACO and obstructive asthma, suggesting that the obstructive asthma driven by smoking is not the same as the one caused by ongoing asthma inflammation.

The doctoral dissertation of M.D. Minna Tommola in the field of lung diseases titled Adult-onset Asthma and Smoking will be publicly examined in the Faculty of Medicine and Health Technology at Tampere University starting at 12 o'clock on Friday 18 September 2020, Arvo bulding Jarmo Visakorpi auditorium, Arvo Ylpön katu 34. The Opponent will be docent Witold Mazur from University of Helsinki. The Custos  will be Professor Hannu Kankaanranta.

The dissertation is available online at

Photo: Tommi Niskanen