Inspiratory-to-total lung capacity ratio predicts mortality in patients with chronic obstructive pulmonary disease

Am J Respir Crit Care Med. 2005 Mar 15;171(6):591-7. doi: 10.1164/rccm.200407-867OC. Epub 2004 Dec 10.

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.

Publication types

  • Multicenter Study

MeSH terms

  • Aged
  • Body Mass Index
  • Cohort Studies
  • Female
  • Follow-Up Studies
  • Humans
  • Inspiratory Capacity
  • Male
  • Predictive Value of Tests
  • Proportional Hazards Models
  • Pulmonary Disease, Chronic Obstructive / diagnosis
  • Pulmonary Disease, Chronic Obstructive / mortality*
  • ROC Curve
  • Risk Factors
  • Survival Analysis
  • Time Factors
  • Total Lung Capacity