• NETT Study Results
  • By Dr. Tom Petty
  • The results of the long awaited National Emphysema Treatment Trial (NETT) on lung volume reduction surgery (LVRS) were recently reported at the annual meetings of the Association of Thoracic Surgeons, and the American Thoracic Society. The nationwide study was done in 17 centers. In all, 1218 patients were enrolled. All received 6-10 weeks of a pulmonary rehabilitation program designed to reach a functional optimum for each participant. 608 were randomized (i.e., by chance) to receive LVRS and to continue with pulmonary rehabilitation and medical therapy. 610 were assigned to medical therapy and further pulmonary rehabilitation. But 5.4% of these left the protocol and had LVRS while another 15 received lung transplants.
  • The mortality rate at 90 days was 7.9% with surgery, compared with 1.3% with medical therapy. Survival was essentially the same after two years. An earlier analysis showed that patients with very low lung function, i.e., FEV1 < 20% and a diffusion test of < 20% had very high mortality and should not receive LVRS. A subset of surgical patients had the greatest increase in exercise tolerance. Costs were far greater with surgery compared with medical therapy.
  • The bottom line message is that only a select group of surgical patients benefit, at high costs, and with a significant mortality risk. The presence of localized disease in the upper parts of the lungs along with poor exercise ability after rehabilitation are considerations for surgery. The most important part of the study was that it established pulmonary rehabilitation as the standard of care for patients with advanced COPD.
  • Thanks to Dr. Petty for his summary of a very long and complex study that physicians will be studying for years. Thanks also to Chris Garvey of Seaton Medical Center for a table that summarizes the material that Dr. Petty presented to you.
  • Exercise capacity after PR
    Lung disease location in lungs
    Effect of Lung Volume Reduction Surgery (LVRS)  
    Low exercise capacity after PR Disease in upper regions of lungs

    Lower mortality

    Improved exercise capacity

    Improved quality of life

    Benefits most
    High exercise capacity after PR, Disease in upper regions of lungs

    No change in mortality

    No benefit in exercise capacity

    Improved quality of life

    Benefits most
    Low exercise capacity after PR, Disease in lower or diffuse regions of lungs

    No change in mortality

    No benefit in exercise capacity

    Somewhat improved quality of life

    Benefits most

    High exercise capacity after PR

    Disease in lower or diffuse regions of lungs

    Increased mortality

    Improved exercise capacity

    No significant improvement in

    quality of life after 2 years

    Benefits most
    FEV1 less than 20% predicted

    Withdrawn from study due to

    high mortality

    Benefits most
  • We know that some of you will be disappointed that the results of LVRS were not more positive. Many people hoped, and expected, that this would be a major breakthrough in the treatment of emphysema for all suffers. The important finding, however, was what those of us who have worked with pulmonary rehab (and LVRS) expected: the value of pulmonary rehab. So, while you may not be a candidate for major surgery, almost all of you can be helped by pulmonary rehab. Expect to hear more about the benefits of PR in the months to come.