The concept, estimation and application of lung age

Lung age is a term that uses effective age to quantify the physiological function of lung. It was firstly proposed to evaluate the lung function impairment caused by smoking. Estimation of lung age can be derived from the lung age predictive equation based on spirometric indices. The predictive equation of lung age can be developed by the rearrangement of the predictive equations of spirometric indices, or the multiple regression analysis based on large data of healthy population. Six studies have developed predictive equations of lung age based on date from different countries (America in 1985, Australia in 2010, America in 2010, Japan in 2012, North Africa in 2014, Japan in 2015). However, limitations in study design, sample size, population source and statistical analysis are shown in these six studies. As for the application of lung age, studies show that lung age may motivate smoking cessation. Lung age is the independent predictor of complications after esophagectomy and the surgery for non-small cell lung cancer, it can be used in the assessment of the treatment efficacy of Reslizumab in asthmatic patients, and it has good sensitivity and specificity in diagnosing lung function dysfunction. Also, lung age is shown to be related to obesity, dyspnea, smoking, chronic obstructive pulmonary disease, asthma, age and height. As a simplification of spirometry results, although lung age cannot offer the complete information of spirometry, it can be easily understood by general public and be implemented by the health care providers, which enables lung age to be a useful tool in the prevention and management of chronic respiratory diseases. It is especially suitable for the application and promotion of primary medical institutions and general practitioners. The present review introduced the concept, estimation and clinical application of lung age, and proposed suggestions about the prospect of lung age.