Predicting inadequate spirometry technique and the use of FEV1/FEV3 as an alternative to FEV1/FVC for patients with mild cognitive impairment

Clin Respir J. 2008 Oct;2(4):208-13. doi: 10.1111/j.1752-699X.2008.00063.x.


Introduction and objectives: Some patients cannot perform forced vital capacity (FVC). We conducted a study to answer three questions: Can the ability to perform components of spirometry be predicted by the Mini Mental State Examination (MMSE)? What proportion of subjects can perform forced expiratory volume in 3 s (FEV3) but not FVC? Does the forced expiratory volume in 1 s (FEV1)/FEV3 ratio concord with FEV1/FVC ratio in patients with airflow obstruction?

Methods: We conducted a prospective observational study of 267 patients with a mean age of 79 years, including subjects with indicators of frailty. They performed spirometry and the MMSE. Spirometric recordings were compared to the American Thoracic Society 1994 criteria.

Results: FVC was achieved by 51% of patients. Inability to perform FVC was predicted by an MMSE < 24 (specificity 94%, sensitivity of 51%). An FEV1/FEV3 ratio < 80% matched a FEV1/FVC ratio < 70% (sensitivity 96%, specificity 97%). Twenty-five percent of subjects were able to reach FEV3 but not FVC; 14% of that group had an MMSE < 24. Subjects with an MMSE < 20 were unable reliably to perform any spirometry.

Conclusion: Patients with an MMSE < 24 are usually unable to reach FVC reliably when tested on a single occasion, but some can reach FEV3. Patients with MMSE < 20 cannot do spirometry. An FEV1/FEV3 ratio < 80% can be used to help identify patients with airflow obstruction if they are unable to perform full spirometry to FVC.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Airway Obstruction / complications
  • Airway Obstruction / diagnosis
  • Cognition Disorders / diagnosis*
  • Cognition Disorders / etiology
  • Female
  • Forced Expiratory Volume / physiology*
  • Humans
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Probability
  • Prospective Studies
  • Pulmonary Disease, Chronic Obstructive / complications
  • Pulmonary Disease, Chronic Obstructive / diagnosis
  • Pulmonary Ventilation / physiology
  • Reference Values
  • Respiratory Mechanics / physiology
  • Risk Assessment
  • Sensitivity and Specificity
  • Severity of Illness Index
  • Spirometry / methods*
  • Vital Capacity / physiology*