Respiratory Symptoms in Young Adults: Prognostic Value for Later Lung Function?
Age-related declines in lung function were worse in individuals who complained of cough, phlegm, or wheezing.
The presence of respiratory symptoms in young adults may be associated with a decline in lung function, chronic obstructive pulmonary disease, and emphysema later in life, independent of smoking status or asthma, according to a study published by the American Journal of Respiratory and Critical Care Medicine.
Data were obtained from 2749 individuals, aged 18 to 30 years, who participated in the prospective Coronary Artery Risk Development in Young Adults (CARDIA) study. The researchers sought to determine whether the presence of respiratory symptoms such as cough, phlegm, episodes of bronchitis, wheezing, shortness of breath, and chest illness present at both baseline and at 2 years was associated with the development of an accelerated decrease in lung function observed through data points such as forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC), development of obstructive or restrictive physiology, and computed tomography findings of visual emphysema. The study was conducted in Birmingham, Alabama; Chicago, Illinois; Minneapolis, Minnesota; and Oakland, California.
A total of 1293 (43.9%) individuals included in the analysis reported ≥1respiratory symptom both at baseline and at year 2 examinations. When observed from year 5 to year 30, individuals with symptoms consistently reported at baseline and year 2 experienced a significant decline in FEV1, FVC, and FEV1/FVC compared with individuals who did not report symptoms, after adjusting for confounding variables such as race-sex group, center, height, year 5 lung function, baseline body mass index, physician-confirmed asthma, and smoking status (–2.71 mL/y, –2.18 mL/y, and –.05 %/y, respectively).
Cough, phlegm, episodes of bronchitis, wheezing, shortness of breath, and chest illness were all associated with greater annual declines in both FEV1 and FEV1/FVC, whereas only wheezing and chest illness were associated with a greater annual decline in FVC. When compared with individuals who did not have respiratory symptoms, age-related declines in lung function (FEV1, FVC, and FEV1/FEC) were greater in individuals who complained of cough, phlegm, or wheezing, whereas episodes of bronchitis were associated with only FEV1 and FEV1/FVC declines and chest illness was associated with only FEV1 and FVC declines.
Smoking was associated with significant future lung impairment and a decline in FEV1, FVC, and FEV1/FVC compared with individuals with similar multivariable models who did not smoke (3.07 mL/y [P <.001], –2.25 mL/y [P =.002], –0.04 %/y [P <.001], respectively). Furthermore, there was a statistically significant multiplicative effect between episodes of bronchitis and reported smoking status on FEV1 decline (P =.001).
Overall, a strong association was found between respiratory symptom complaints in young adults and the future development of lung disease with either postbronchodilator obstructive (odds ratio [OR], 1.62; 95% CI, 1.10-2.40) or restrictive (OR, 1.44, 95% CI, 1.10-1.88) physiology. Cough-related symptoms (OR, 1.56; 95% CI, 1.08-2.26) such as coughing, phlegm, episodes of bronchitis, and chest illnesses were associated with higher odds for postbronchodilator obstruction, but not restrictive physiology (OR, 1.27; 95% CI, 0.96-1.66), which was associated with shortness of breath. Of note, the incident prebronchodilator obstructive and restrictive physiology was not statistically significantly associated with smoking or with an asthma diagnosis (P >.05).
Researchers concluded, through physiologic testing and computed tomography imaging, that the accelerated age-related decline in lung function and development of obstructive and restrictive lung disease during the subsequent 30 years were associated with respiratory symptoms reported during young adulthood. Therefore, clinicians should investigate respiratory symptoms present in young adults as they could provide prognostic value and affect their future lung health.
Kalhan R, Dransfield MT, Colangelo, LA, et al. Respiratory symptoms in young adults and future lung disease: the CARDIA lung study [published online January 25, 2018]. Am J Respir Crit Care Med. doi:10.1164/rccm.201710-2108OC