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National Emphysema Treatment Trial (NETT)

This study has been completed.
Information provided by:
National Heart, Lung, and Blood Institute (NHLBI) Identifier:
First received: October 27, 1999
Last updated: April 13, 2016
Last verified: April 2009
To evaluate the long term efficacy, morbidity and mortality associated with medical therapy with lung volume reduction surgery (LVRS) as compared to medical therapy alone and to define patient selection criteria. The trial, conducted in conjunction with a patient registry, is supported by the NHLBI, the Centers for Medicare and Medicaid Services (CMS), and the Agency for Healthcare Research and Quality (AHRQ).

Condition Intervention Phase
Emphysema Lung Diseases Lung Diseases, Obstructive Chronic Obstructive Pulmonary Disease Procedure: Lung volume reduction surgery Phase 3

Study Type: Interventional
Study Design: Allocation: Randomized
Primary Purpose: Treatment

Resource links provided by NLM:

Further study details as provided by National Heart, Lung, and Blood Institute (NHLBI):

Study Start Date: December 1996
Study Completion Date: December 2005
Primary Completion Date: December 2005 (Final data collection date for primary outcome measure)
Detailed Description:


LVRS is intended primarily for those patients whose chronic obstructive pulmonary disease (COPD) is predominantly emphysema. Emphysema is characterized anatomically "by abnormal, persistent enlargement of the airspaces distal to the terminal bronchioles, accompanied by the destruction of the airspace walls and without obvious fibrosis". The loss of the lung architecture leads to compressible peripheral airways that close at higher than normal lung volumes (early airway closure). The increased compliance and the air trapping from early closure leads to hyperinflation of the lung, over distention of the chest wall, a flattened, disadvantaged diaphragm, and ventilation-perfusion mismatch. In the 1950s and 1960s, Dr. Otto Brantigan theorized that surgical excision of multiple wedges of lung would reduce lung volumes, thereby restoring the outward elastic pull on the small airways and reduce airway obstruction. Dr. Brantigan reported that the surgical excision of lung tissue resulted in significant clinical improvement in some cases, but mortality was high. With little objective data and high mortality, the procedure did not gain widespread acceptance.

The experience that diaphragmatic and chest wall function could be restored in emphysema with lung transplantation renewed interest in Dr. Brantigan's work. Improvements in surgical technique have opened the possibility of performing surgical excisions of lung tissue. Recent reports on LVRS have shown improvements in FEV1, FVC, TLC, RV and dyspnea and quality of life assessments.

These reports generated enormous excitement among patients and their doctors. Many centers around the country started performing LVRS with the result that hundreds of patients had the procedure, despite the preliminary nature of the results, the lack of rigorous patient selection criteria and the lack of information on long term outcome. Basic questions remain such as which patient should have the surgery, what protocol should be followed, what physiological tests should be obtained, and what is the long term efficacy of the technique on morbidity, mortality, and quality of life. The mechanisms of benefit and the full cardiopulmonary consequences are unknown.

The concept for the trial originated in the NHLBI Workshop on Evaluation and Research in Lung Volume Reduction Surgery. The initiative was reviewed and approved at the May 1996 National Heart, Lung, and Blood Advisory Council meeting. The Requests for Proposals were released in June, 1996.


In the trial, 1218 eligible patients were randomized to receive either medical therapy (610) or medical therapy with LVRS(608). LVRS was performed by median sternotomy or video-assisted thorascopic surgery (VATS). Centers randomized their patients to either a) medical therapy alone versus medical therapy with LVRS by median sternotomy, b) medical therapy alone versus medical therapy with LVRS by VATS, or c) medical therapy alone versus medical therapy with LVRS by median sternotomy versus medical therapy with LVRS by bilateral VATS. Medical therapy included pulmonary rehabilitation and education. Direct comparisons of the two surgical techniques were possible only at the centers that performed both techniques. All arms included intensive pulmonary rehabilitation. The primary endpoints were survival and functional improvement as assessed by maximum workload. Secondary endpoints included morbidity, improvement in pulmonary function, quality of life and performance of activities of daily living. Follow-up exams, including history, physical exams, pulmonary function tests, exercise tests and quality of life assessments, occurred after pre-operative rehabilitation and six and twelve months after surgery and every twelve months thereafter. Recruitment ended July 31, 2002 and follow-up ended in December, 2002.


Ages Eligible for Study:   up to 100 Years   (Child, Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No
Men and women with end-stage emphysema.
  Contacts and Locations
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Please refer to this study by its identifier: NCT00000606

Sponsors and Collaborators
National Heart, Lung, and Blood Institute (NHLBI)
OverallOfficial: Steven Piantadosi Johns Hopkins University
  More Information

Additional Information:

Study Data/Documents: Individual Participant Data Set  This link exits the site
Identifier: NETT
NHLBI provides controlled access to IPD through BioLINCC. Access requires registration, evidence of local IRB approval or certification of exemption from IRB review, and completion of a data use agreement.

Publications automatically indexed to this study by Identifier (NCT Number): Identifier: NCT00000606     History of Changes
Other Study ID Numbers: 218
Study First Received: October 27, 1999
Last Updated: April 13, 2016

Additional relevant MeSH terms:
Lung Diseases
Lung Diseases, Obstructive
Pulmonary Disease, Chronic Obstructive
Pulmonary Emphysema
Respiratory Tract Diseases
Pathologic Processes processed this record on September 21, 2017