The influence of cigarette smoking on lung function in patients with idiopathic pulmonary fibrosis.
Schwartz-DA; Merchant-RK; Helmers-RA; Gilbert-SR; Dayton-CS; Hunninghake-GW
Am Rev Respir Dis 1991 Sep; 144(3)(Pt 1):504-506
The effect of cigarette smoking on lung function in patients with idiopathic pulmonary fibrosis (IPF) was investigated. The cohort consisted of 73 patients with clinically diagnosed IPF (45 males), 24.5 to 82.6 years (yr) old. Twenty one were never smokers, 44 were former smokers, and seven were current smokers. The mean number of pack years of smoking of the smoking group was 26.7. One second forced expiratory volume (FEV1), forced vital capacity (FVC), the FEV1/FVC ratio, total lung capacity (TLC), residual volume (RV), FRC, and carbon-monoxide diffusing capacity (DLco) were measured. Associations between the pulmonary function variables and smoking were examined by logistic regression techniques. Current smokers had significantly greater RVs than never smokers. Univariate analysis revealed that pack years of smoking was significantly, positively associated with large lung volumes, as manifested by increases in TLC, RV, and FRC, and impaired gas exchange, as indicated by decreases in DLco. Multivariate analysis revealed that current smoking was significantly associated with increases in RV and FRC and pack years of smoking was inversely related to DLco after controlling for potential confounders and interventions such as open lung biopsy or immunosuppressive therapy. Measures of air flow obstruction such as the FEV1/FVC ratio were not associated with smoking status or pack years of smoking. The authors conclude that cigarette smoking increases variables related to lung volume and decreases gas exchange among patients with IPF, and that IPF tends to obscure the effect of smoking on variables related to air flow. Traditional measures of lung volume may not be helpful in identifying the presence and extent of restrictive lung function in cigarette smokers with IPF.
NIOSH-Grant; Pulmonary-system-disorders; Cigarette-smoking; Lung-fibrosis; Pulmonary-function-tests; Epidemiology; Humans
Internal Medicine University of Iowa Pulmonary Disease Division Iowa City, IA 52242
Pulmonary System Disorders
American Review of Respiratory Disease
University of Iowa, Iowa City, Iowa