Absolute lung size and the sex difference in breathlessness in the general population

PLoS One. 2018 Jan 5;13(1):e0190876. doi: 10.1371/journal.pone.0190876. eCollection 2018.

Abstract

Background: Breathlessness is associated with major adverse health outcomes and is twice as common in women as men in the general population. We evaluated whether this is related to their lower absolute lung volumes.

Methods: Cross-sectional analysis of the population-based Swedish CardioPulmonarybioImage Study (SCAPIS) Pilot, including static spirometry and diffusing capacity (n = 1,013; 49% women). Breathlessness was measured using the modified Medical Research Council (mMRC) scale and analyzed using ordinal logistic regression adjusting for age, pack-years of smoking, body mass index, chronic airway limitation, asthma, chronic bronchitis, depression and anxiety in all models.

Results: Breathlessness was twice as common in women as in men; adjusted odds ratio (OR) 2.20 (95% confidence interval, 1.32-3.66). Lower absolute lung volumes were associated with increased breathlessness prevalence in both men and women. The sex difference in breathlessness was unchanged when adjusting for lung function in %predicted, but disappeared when controlling for absolute values of total lung capacity (OR 1.12; 0.59-2.15), inspiratory capacity (OR 1.26; 0.68-2.35), forced vital capacity (OR 0.84; 0.42-1.66), forced expiratory volume in one second (OR 0.70; 0.36-1.35) or lung diffusing capacity (OR 1.07; 0.58-1.97).

Conclusion: In the general population, the markedly higher prevalence of breathlessness in women is related to their smaller absolute lung volumes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cross-Sectional Studies
  • Dyspnea / physiopathology*
  • Female
  • Humans
  • Lung / anatomy & histology*
  • Lung / physiopathology
  • Male
  • Middle Aged
  • Respiratory Function Tests
  • Sex Factors*
  • Sweden

Grant support

The main funding body of The Swedish CArdioPulmonary bioImage Study (SCAPIS) was the Swedish Heart and Lung Foundation (GB, AR and KT). The study was also funded by the Knut and Alice Wallenberg Foundation, the Swedish Research Council (VR), VINNOVA and the Swedish Council for Working Life, Health, and Welfare (FORTE) (GB, AR and KT). In addition, there was support from the Sahlgrenska University Hospital, and grants from the Swedish state under the agreement concerning research and education of doctors in Western Sweden and from the Sahlgrenska Academy at University of Gothenburg (GB, AR and KT). ME was supported by unrestricted grants from The Swedish Society of Medicine, the Swedish Respiratory Society, the Swedish Heart-Lung Foundation, the Scientific Committee of Blekinge County Council, and the Wera and Emil Cornell Foundation (ME). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.