The ratio of FEV1 to FVC as a basis for establishing chronic obstructive pulmonary disease

Am J Respir Crit Care Med. 2010 Mar 1;181(5):446-51. doi: 10.1164/rccm.200909-1366OC. Epub 2009 Dec 17.


Rationale: The lambda-mu-sigma (LMS) method is a novel approach that defines the lower limit of normal (LLN) for the ratio of FEV1/FVC as the fifth percentile of the distribution of Z scores. The clinical validity of this threshold as a basis for establishing chronic obstructive pulmonary disease is unknown.

Objective: To evaluate the association between the LMS method of determining the LLN for the FEV1/FVC, set at successively higher thresholds, and clinically meaningful outcomes.

Methods: Using data from a nationally representative sample of 3,502 white Americans aged 40-80 years, we stratified the FEV1/FVC according to the LMS-LLN, with thresholds set at the 5th, 10th, 15th, 20th, and 25th percentiles (i.e., LMS-LLN5, LMS-LLN10, etc.). We then evaluated whether these thresholds were associated with an increased risk of death or prevalence of respiratory symptoms. Spirometry was not specifically completed after a bronchodilator.

Measurements and main results: Relative to an FEV1/FVC greater than or equal to LMS-LLN25 (reference group), the risk of death and the odds of having respiratory symptoms were elevated only in participants who had an FEV1/FVC less than LMS-LLN(5), with an adjusted hazard ratio of 1.68 (95% confidence interval, 1.34-2.12) and an adjusted odds ratio of 2.46 (95% confidence interval, 2.01-3.02), respectively, representing 13.8% of the cohort. Results were similar for persons aged 40-64 years and those aged 65-80 years.

Conclusions: In white persons aged 40-80 years, an FEV1/FVC less than LMS-LLN5 identifies persons with an increased risk of death and prevalence of respiratory symptoms. These results support the use of the LMS-LLN5 threshold for establishing chronic obstructive pulmonary disease.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adult
  • Age Factors
  • Aged
  • Aged, 80 and over
  • Chi-Square Distribution
  • Female
  • Forced Expiratory Volume / physiology*
  • Humans
  • Male
  • Middle Aged
  • Proportional Hazards Models
  • Pulmonary Disease, Chronic Obstructive / diagnosis*
  • Pulmonary Disease, Chronic Obstructive / epidemiology
  • Pulmonary Disease, Chronic Obstructive / physiopathology
  • Reference Values
  • Sex Factors
  • United States / epidemiology
  • Vital Capacity / physiology*