Association of circadian syndrome and lung health: A population-based cohort study.

Background: Few studies have explored the association between circadian syndrome (CircS) and lung health.

Objective: To access the relationship between CircS and lung health.

Methods: This prospective cohort study enrolled 6,252 adults. Multivariable logistic and linear regression models were employed to examine the association between CircS and the prevalence of chronic lung disease, respiratory symptoms, and lung function, as appropriate. Receiver operating characteristic curve analysis was used to compare the predictive power of the number of metabolic syndrome (MetS) and CircS components for lung health. Kaplan-Meier survival and multiple Cox regression analyses were used to assess the relationship between CircS and all-cause mortality. The effects of CircS on health-related quality of life (HQL) and health care use were also evaluated.

Results: Participants with CircS were significantly associated with a higher prevalence of asthma, chronic bronchitis, cough, wheeze, phlegm production, and exertional dyspnea. The number of CircS components demonstrated better predictive power for the prevalence of asthma, chronic bronchitis, emphysema, cough, wheeze, phlegm production, and exertional dyspnea than the number of MetS components. Higher numbers of CircS components were significantly associated with decreased forced expiratory volume in the first second (FEV) and forced vital capacity (FVC), worse HQL, and increased health care use. Longitudinally, participants with CircS exhibited a higher risk of all-cause mortality than those without CircS.

Conclusions: Our results support the claim of that CircS is a better predictor of lung health than the Mets in adults in the United States. Elevated CircS levels are associated with poorer lung function, increased health care use, worse HQL, and a higher risk of mortality.