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Dysanapsis and COPD risk

Benjamin Smith, JAMA 2020. Jun 9;323(22):2268-2280. Figure 1. These CT scans of airways (red) and lungs (dark grey) show the spectrum of dysanapsis, with smaller airways in proportion to lung size (left) compared with normal size airways (middle), and larger than normal airways (right).

A new study by Dr. Benjamin Smith highlights dysanapsis as a strong risk factor for chronic obstructive pulmonary disease (COPD). Dysanapsis is a developmental mismatch between airway and lung size. While smoking has long been known as the best-known risk factor for COPD, it never explained why only a minority of lifelong smokers develop the disease, while non-smokers represent more than 25% of all COPD cases.

The team conducted detailed analysis of lung images and assessed standard COPD risk factors such as tobacco smoking, secondhand smoke, air pollution and occupational exposures. Their results show that dysanapsis appears to be a very strong risk factor for COPD, associated with twice as much of the variation in COPD risk when compared with cigarette smoking and other standard COPD risk factors. When the researchers measured airway tree and lung size using state-of-the-art CT scans of the chest, they discovered that never smokers with COPD had much smaller airways relative to lung size, whereas the heavy smokers who did not have COPD had unusually large airways and thus found themselves at the opposite end of the dysanapsis spectrum. While the root cause for dysanapsis remains unknown, these findings help understand why COPD can occur in people who never smoked and do not have other risk factors.

Read more about the study here

Why do some non-smokers get COPD while many heavy smokers don’t? A new study highlights a strong risk factor for COPD related to lung development. RI-MUHC News. June 9, 2020.

Read the article here:

Association of Dysanapsis With Chronic Obstructive Pulmonary Disease Among Older Adults. Smith BM, Kirby M, Hoffman EA, Kronmal RA, Aaron SD, Allen NB, Bertoni A, Coxson HO, Cooper C, Couper DJ, Criner G, Dransfield MT, Han MK, Hansel NN, Jacobs DR Jr, Kaufman JD, Lin CL, Manichaikul A, Martinez FJ, Michos ED, Oelsner EC, Paine R 3rd, Watson KE, Benedetti A, Tan WC, Bourbeau J, Woodruff PG, Barr RG; MESA Lung, CanCOLD, and SPIROMICS Investigators. JAMA. 2020 Jun 9;323(22):2268-2280. doi: 10.1001/jama.2020.6918. PMID: 32515814

Dr. Benjamin Smith is a member of the Meakins-Christie Laboratories and a scientist at the Research Institute of the McGill University Health Centre – RESP program.