Dysanapsis is associated with a higher incidence of chronic obstructive pulmonary disease (COPD) in older adults, according to study results published in JAMA.
Researchers performed a retrospective analysis of the multicenter Multi-Ethnic Study of Atherosclerosis (MESA) Lung Study (n=2531; mean age, 69 years) conducted between 2010 and 2018, the multicenter Canadian Cohort of Obstructive Lung Disease (CanCOLD) case-control study (n=1272; mean age, 67 years) also conducted between 2010 to 2018, and the multicenter Subpopulations and Intermediate Outcome Measures in COPD Study (SPIROMICS) conducted between 2011 and 2016 (n=2726; mean age, 65 years).
All participants underwent baseline chest computed tomography to identify dysanapis, which was measured as the geometric mean of airway lumen diameters in centimeters at 19 anatomic locations divided by the cube root of lung volume. The primary outcome of the analysis was COPD, which was defined by the postbronchodilator ratio of forced expired volume in the first second (FEV1) to forced vital capacity (FVC) <0.70 with accompanying respiratory symptoms. The secondary outcomes included FEV1:FVC, FEV1, and FVC as continuous variables. Analyses were adjusted for both demographics and COPD risk factors, including asthma, tobacco smoke exposure, as well as occupational and environmental pollutants.
Approximately 9.4% (n=237) of participants in the MESA Lung Study had prevalent COPD. The mean airway to lung ratio in this population was 0.033, and the mean FEV1 decline was -33 mL/y. Additionally, 4.3% (n=98) of participants in this cohort without prevalent COPD had incident COPD for a median of 6.2 years.
Participants from the MESA Lung Study who were in the lowest quartile of airway to lung ratio had a higher incidence of COPD compared with participants in the highest quartile (9.8 vs 1.2 cases per 1000 person-years, respectively; adjusted rate ratio [RR], 8.12; 95% CI, 3.81-17.27; rate difference, 8.6 cases per 1000 person-years; 95% CI, 7.1-9.2; P <.001). No difference was found between the highest quartile and lowest quartile in terms of FEV1 decline (-31 vs -33 mL/year; difference, 2 mL/y; 95% CI, -2 to 5; P =.30).
Approximately 15% of patients in the CanCOLD study had incident COPD (median, 3.1 years). The mean decline in FEV1 was -36 mL/y. The incidence of COPD in the lowest airway to lung quartile was higher than was observed in the highest quartile (80.6 vs 24.2 cases per 1000 person-years, respectively; adjusted RR, 3.33; 95% CI, 1.89-5.85; adjusted rate difference, 56.4 cases per 1000 person-years; 95% CI, 38.0-66.8; P <.001). No difference was found between the quartiles in regard to the FEV1 decline (-34 vs -36 mL/y; difference, 1 mL/y; 95% CI, -15 to 16; P =.97).
In the SPIROMICS cohort, participants with COPD who were in the lowest airway to lung ratio quartile featured an average decline in FEV1 of -37 mL/y. This was not significantly different from the decline observed in participants in the MESA Lung Study (P =.98). Participants of the SPIROMICS who were in the highest quartile did show a more rapid decline compared with participants in the MESA Lung Study (-55 mL/y; difference, -17 mL/y; 95%CI, -32 to -3; P =.004).
A limitation of the analysis was the primary focus on lung function decline, despite the multidimensional nature of disease progression.
Based on their findings, the investigators of this analysis suggested that “dysanapsis was significantly associated with COPD, with lower airway caliber relative to lung size associated with greater COPD risk.”
Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.
Smith BM, Kirby M, Hoffman EA, et al; for the MESA Lung, CanCOLD, and SPIROMICS Investigators. Association of dysanapsis with chronic obstructive pulmonary disease among older adults. JAMA. 2020;323(22):2268-2280.