Respiratory Trials·org

COPD · Lung volume reduction

NETT

National Emphysema Treatment Trial

NETT trial design and results
Design Multicentre randomised trial
Treatment Lung volume reduction surgery plus medical therapy
Control Medical therapy alone
Population 1218 patients with severe emphysema
Follow-up Median 29 months
Primary endpoint Mortality and maximal exercise capacity at 24 months
Result Overall mortality 0.11 deaths per person-year in both groups (risk ratio 1.01, p=0.90). Exercise capacity improved by more than 10 W in 15% after surgery versus 3% with medical therapy (p<0.001). Among patients with predominantly upper-lobe emphysema and low exercise capacity, mortality was lower with surgery (risk ratio 0.47, p=0.005). Patients with non-upper-lobe emphysema and high exercise capacity did worse.
Secondary endpoints Quality of life, lung function, subgroup outcomes by emphysema distribution

Overall, lung-volume-reduction surgery increases the chance of improved exercise capacity but does not confer a survival advantage over medical therapy. It does yield a survival advantage for patients with both predominantly upper-lobe emphysema and low base-line exercise capacity.

The trial authors, in the published abstract

How it has aged

A model of how to rescue a neutral trial: the subgroup analysis was prespecified, and it defined the phenotype that still selects patients for volume reduction today. It also identified who is harmed — non-upper-lobe disease with preserved exercise capacity. Bronchoscopic valves have since taken over much of this ground.

Publications

A randomized trial comparing lung-volume-reduction surgery with medical therapy for severe emphysema

Fishman A, Martinez F, Naunheim K, et al. A randomized trial comparing lung-volume-reduction surgery with medical therapy for severe emphysema. N Engl J Med 2003 May 22;348(21):2059-73.

  • No overall survival advantage over medical therapy
  • Improved exercise capacity in 15% versus 3%
  • Survival benefit confined to upper-lobe emphysema with low baseline exercise capacity
  • Increased mortality in non-upper-lobe emphysema with high exercise capacity