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Chinese measured spirometry data. The present study also compared with other published Chinese equations for spirometry. Results: A total of 7,115 eligible individuals aged 4 to 80 years (50.9% females) were recruited. Reference equations against age and height by gender were established, including predicted values and lower limits of normal (LLNs). Validated with Chinese data, the mean percentage differences of Caucasian reference values adjusted with ethnic conversion factors were −10.2% to 1.8%, and the percentages of total subjects under LLNs were 0.1% to 8.9%. Compared with this study, the percentage differences of previous Chinese studies ranged from −17.8% to 11.4%, which were found to significantly overestimate or underestimate lung IntroductionSpirometry has been widely used for diagnosing respiratory diseases, quantifying disease severity, and assessing disease prognosis (1,2). Accurate interpretation of spirometry requires appropriate reference values derived from its own ancestry population (3), including lower limits of normal (LLNs), which could be helpful for assessment of abnormal pulmonary function in patients with pulmonary diseases.There are over 40 million overseas Chinese (4) and 1.3 billion mainland Chinese (5) in the world (about 22% of the global population), indicating the huge medical demand (6). Embarrassingly, standardized nationwide spirometric reference values for Chinese were unavailable.In 2012, Global Lung Function Initiative (3) recommended multi-ethnic reference values for African-Americans, Southeast Asians (SEA-GLI2012) and Northeast Asians (NEA-GLI2012), which were largely established with Caucasian data and adjusted with fixed ethnic conversion factors in the whole age range. In addition, other Caucasian reference values adjusted with fixed ethnic conversion factors were also applied in China (7,8), such as European Committee of Steel and Coal equations adjusted for Chinese with the suggestion of Zheng et al. (Chinese-ECSC1993) (9,10), and the third national health and nutrition examination surveys equations adjusted with 0.88 times for Asian-American (Asian-NHANESIII 0.88) (11,12). Given the dynamic changes of gene, economic, environment, nutrition and et al., it remains unknown whether those fixed ethnic conversion factors reliably reflect the difference of spirometry between Caucasians and Chinese.Although several spirometric reference values for Chinese have been published (13-22), the major disadvantages in these studies limited the nationwide use, including small samples, limited age ranges, small local regions, as well as different study protocols and quality control. Without LLNs for nationwide Chinese, a fixed 0.7 of forced expiratory volume in 1 second to forced vital capacity (FEV 1 /FVC) instead of LLNs was frequently applied for the diagnosis of "airflow limitation" in previous studies (7,23,24), leading possible underdiagnosis in younger subjects and over diagnosis in elderly. Moreover, In the nationwide questionnaire surveys on clinical application of pulmon...

We identified IL1B was significantly up-regulated in COPD small airway epithelial cells and propose IL1B as a novel player in airway inflammation in COPD.