Chest
Volume 140, Issue 3, September 2011, Pages 598-603
Journal home page for Chest

Original Research
Pulmonary Function Testing
Grading the Severity of Obstruction in Mixed Obstructive-Restrictive Lung Disease

https://doi.org/10.1378/chest.10-2860Get rights and content

Background

The severity of obstructive pulmonary disease is determined by the FEV1 % predicted based on the American Thoracic Society/European Respiratory Society (ATS/ERS) guidelines. In patients with coexisting restrictive lung disease, the decrease in FEV1 can overestimate the degree of obstruction. We hypothesize that adjusting the FEV1 for the decrease in total lung capacity (TLC) results in a more appropriate grading of the severity of obstruction.

Methods

We examined a large pulmonary function test database and identified patients with both restrictive (TLC < 80% predicted) and obstructive (FEV1/FVC < the lower limit of normal) lung disease. FEV1 % predicted was adjusted for the degree of restriction by dividing it by TLC % predicted. We compared the distribution of severity grading between adjusted and unadjusted values according to ATS/ERS criteria and determined how the distribution of severity would change based on asthma and COPD guidelines.

Results

We identified 199 patients with coexisting restrictive and obstructive lung disease. By ATS/ERS grading, the unadjusted data categorized 76% of patients as having severe or very severe obstruction and 11% as having mild or moderate obstruction. The adjusted data classified 33% with severe or very severe obstruction and 44% with mild or moderate obstruction. Of the corrected values, 83% resulted in a change to less severe obstruction by ATS/ERS guidelines, and 44% and 70% of patients, respectively, would be reclassified as having less severe obstruction by current asthma and COPD guidelines.

Conclusions

This method results in a more appropriate distribution of severity of obstruction, which should lead to more accurate treatment of obstruction in these patients.

Section snippets

Materials and Methods

We analyzed a large database of pulmonary function tests (PFTs) collected at St. Louis University Hospital. Equipment and techniques were unchanged throughout the study period and strictly conformed to ATS/ERS criteria for quality.14, 15 The study received exempt status approval from the St. Louis University Biomedical Institutional Review Board (#16311) and the University of Vermont Committees on Human Research (#10-055) because all data were deidentified at the time of analysis.

We identified

Results

We identified a total of 199 patients with coexisting restrictive and obstructive lung disease. Of these patients, 37% were women and 74% were white (Table 1). The mean age was 56 ± 14 years; the mean FEV1, 1.5 ± 0.6 L (42 ± 14% predicted); mean FEV1/FVC, 0.61 ± 0.06; and mean TLC, 4.5 ± 1 L (71 ± 7% predicted). Based on referral requests, patients had a variety of lung diseases, which were categorized into obstructive diseases (eg, asthma, COPD, bronchiectasis), interstitial lung diseases (eg,

Discussion

Current ATS/ERS guidelines1 recommend using the FEV1 % predicted to grade the severity of lung disease in the presence of obstruction, restriction, or mixed disorders. Because FEV1 is such a strong, independent predictor of health status, this recommendation is sensible. However, in the presence of mixed disorders, the severity of the obstructive component alone also might be assessed on the basis of FEV1, an approach that would be expected to overestimate the degree of obstruction because the

Acknowledgments

Author contributions: Dr Kaminsky had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Dr Gardner: contributed to the study design; data collection, analysis, and interpretation; and writing of the manuscript.

Mr Ruppel: contributed to the data collection and interpretation and review of the manuscript.

Dr Kaminsky: contributed to the study design; data collection, analysis, and interpretation; and writing of

References (24)

  • American Thoracic Society

    Lung function testing: selection of reference values and interpretative strategies

    Am Rev Respir Dis

    (1991)
  • C Agusti et al.

    Clinical and functional assessment of patients with idiopathic pulmonary fibrosis: results of a 3 year follow-up

    Eur Respir J

    (1994)
  • Cited by (24)

    • Classification of obstructive and non-obstructive pulmonary diseases on the basis of spirometry using machine learning techniques

      2022, Journal of Computational Science
      Citation Excerpt :

      Any performance deterioration was caused by lack of rich enough training data which can be attributed to common physiological and structural causes or symptoms of the two classes. Also, there are evidences in the literature which showed that obstructive and non-obstructive diseases are co-existent in a small fraction of patients [23,24]. This may lead to wrong diagnostic annotations of patients for supervised learning.

    • Mixed Ventilatory Defects in Pulmonary Sarcoidosis: Prevalence and Clinical Features

      2020, Chest
      Citation Excerpt :

      In all subgroup analyses, age, male sex, and Dlco levels were independent predictors of mortality on multivariate Cox regression analysis performed for each of the aforementioned comparisons, whereas chest radiographic stage IV disease and different ventilatory pattern were not. We report the prevalence and clinical associations of a mixed ventilatory defect in pulmonary sarcoidosis, previously described in only 23 patients.1-9 In the current cohort, 115 patients were identified with mixed disease according to ATS/ERS criteria.

    • Pulmonary Function Testing

      2015, Murray and Nadel's Textbook of Respiratory Medicine: Volume 1,2, Sixth Edition
    • Pulmonary Function Testing

      2012, Clinical Respiratory Medicine: Fourth Edition
    View all citing articles on Scopus

    Funding/Support: This work was supported by the Vermont Lung Center.

    Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestpubs.org/site/misc/reprints.xhtml).

    View full text