Characteristics and Risk Factors of Preserved Ratio Impaired Spirometry in Physical Examination Population

Abstract

Background Preserved Ratio Impired Spirometry (PRISm) refers to the non-obstructive pulmonary function abnormalities with a decrease forced expiratory volume in one second (FEV1) while the FEV1/forced vital capacity (FVC) remains constant. The PRISm population may be one of the pre-chronic obstructive pulmonary disease (COPD) populations. However, the incidence, characteristics and risk factors of PRISm in the physical examination population in China are still unknown. Objective To analyze the characteristics and influencing factors of PRISm in physical examination population. Methods From January 2017 to December 2019, a total of 970 patients received physical examination in the Third Medical Center of Chinese PLA General Hospital were selected. The baseline data and physical examination results were collected, pulmonary function was measured for vital capacity (VC), FVC, FEV1, forced expiratory volume in six second (FEV6), FEV1/FVC, peak expiratory flow (PEF), FEF25, FEF50 and FEF75, the relevant indexes were expressed as "%pre" as a percentage of the expected value. The included subjects were divided into the airflow obstruction group with FEV1/FVC<0.7 (n=61), PRISm group with FEV1/FVC≥0.7 and FEV1%pre<0.8 (n=111), normal lung function group with FEV1/FVC≥0.7 and FEV1%pre≥0.8 (n=798) according to FEV1/FVC and FEV1%pre. The incidence of PRISm in physical examination population was calculated, the basic characteristics and the characteristics of lung function indexes were compared, the ordinal logistic regression analysis were used to analyze the influencing factors of lung function impairment. Results The incidence of PRISm was 11.4% and the incidence of airflow obstruction was 6.3% in 970 patients. The proportion of people over 60 years old in the PRISm group and the airflow obstruction group was higher than that the normal lung function group, and the proportion of people between 41 and 60 years old was lower than the normal lung function group (P=0.019). The proportion of smokers in the PRISm group was significantly higher than the normal lung function group (P<0.001). The proportion of patients with hypertension in the PRISm group was higher than the normal lung function group (P=0.03). VC%pre, FVC%pre, FEV1%pre, FEV6%pre, PEF%pre, FEF25%pre, FEF50%pre, FEF75%pre were higher in the normal lung function group than the PRISm group and the airflow obstruction group (P<0.001) ; VC%pre, FVC%pre, FEV6%pre, PEF%pre, FEF25%pre, FEF50%pre, and FEF75%pre were higher in the PRISm group than the airflow obstruction group (P<0.05). FEV1/FVC in the normal lung function group and PRISm group was higher than the airflow obstruction group (P<0.001). The ordinal logistic regression analysis with different groups of lung function as dependent variables showed that age>60 years (OR=0.951, 95%CI=0.602-1.504, P=0.002), smoking history (OR=2.201, 95%CI=1.519-3.187, P<0.001) and history of hypertension (OR=1.673, 95%CI=1.106-3.187, P=0.015) were risk factors for lung function impairment in the physical examination population. Conclusion PRISm is common in physical examination population. Attention should be paid to the changes in lung function in those aged >60 years old, with the history of smoking and hypertension. Early intervention may alleviate the progression of COPD.

Keywords

• prism|lung function|physical examination population|physical examination|root cause analysis