title: Inspiratory-to-total lung capacity ratio predicts mortality in patients with chronic obstructive pulmonary disease.
abstract: Static lung hyperinflation has important clinical consequences in patients with chronic obstructive pulmonary disease. We analyzed the power of lung hyperinflation as measured by the inspiratory capacity-to-total lung capacity ratio (IC/TLC) to predict mortality in a cohort of 689 patients with chronic obstructive pulmonary disease (95% males; FEV(1), 1.17 L) with a mean follow-up of 34 months. We also compared the predictive value of IC/TLC with that of the BODE (body mass index, airflow obstruction, dyspnea, exercise performance) Index. Subjects who died (183; 27%) were older; had lower body mass index, FEV(1), and IC/TLC ratio; walked less in the 6-minute walking distance; and had more dyspnea, a higher BODE Index, and comorbidity (p < 0.001). On the basis of logistic regression analysis, IC/TLC was found to be a good and independent predictor of all-cause and respiratory mortality. On the basis of receiver operating characteristic Type II curves, IC/TLC compared favorably with FEV(1) and predicted mortality independently of the BODE Index. We conclude that IC/TLC is an independent risk factor for mortality in subjects with chronic obstructive pulmonary disease. We propose that this ratio be considered in the assessment of patients with chronic obstructive pulmonary disease.
authors.affiliation: Respiratory Research Institute, Hospital Universitario la Candelaria, Carretera del Rosario s/n, 38010 Santa Cruz de Tenerife, Spain. ccasanova@canarias.org
authors.forename: Ciro
authors.initials: C
authors.lastname: Casanova
authors.forename: Claudia
authors.initials: C
authors.lastname: Cote
authors.forename: Juan P
authors.initials: JP
authors.lastname: de Torres
authors.forename: Armando
authors.initials: A
authors.lastname: Aguirre-Jaime
authors.forename: Jose M
authors.initials: JM
authors.lastname: Marin
authors.forename: Victor
authors.initials: V
authors.lastname: Pinto-Plata
authors.forename: Bartolome R
authors.initials: BR
authors.lastname: Celli
mesh_terms: D000368:Aged; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007320:Inspiratory Capacity; D008297:Male; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000401:mortality*; D012372:ROC Curve; D012307:Risk Factors; D016019:Survival Analysis; D013997:Time Factors; D014109:Total Lung Capacity