Part 2 of Criner et al’s concise clinical review on the lessons learned from the National Emphysema Treatment Trial (NETT), which completed follow-up in December 2002 and whose findings were published in NEJM in 2003.
The most interesting point here is that despite evidence of benefit, lung volume reduction surgery (LVRS) is almost never performed: in 2006, only 105 Medicare beneficiaries underwent LVRS in the U.S. Authors suggest that’s due to an overinflated perception of the mortality risk of LVRS by physicians.
- Among 1,218 subjects, NETT showed that lung volume reduction surgery (LVRS) improved survival, exercise capacity and quality of life overall (risk ratio for death at 5 years, 0.86). Subgroup analysis revealed only those with upper lobe-predominant emphysema benefited.
- The subgroup with upper-lobe predominant emphysema and a low exercise tolerance were most likely to gain a survival benefit, and also improved exercise capacity.
- Those with upper lobe predominant emphysema and a high exercise tolerance had improvement in exercise capacity and quality of life, but no survival benefit.
- Non-candidates for LVRS (due to a 16% 30-day mortality in NETT) include those with FEV1 <= 20% predicted and either a diffusing capacity for carbon monoxide < 20% or homogenous emphysema.
- Patients without those high-risk characteristics had only a 2.2% 30-day mortality with LVRS (ten times their 0.2% 30-day mortality with medical therapy).
After 4 years of follow-up, LVRS reduced the death rate from 0.13 deaths-per-person-year with medical management to 0.11. That’s an absolute 0.02 reduction, which is a number needed to treat of 10 to prevent one of their deaths within 5 years.
Successful lung volume reduction surgery reduces need for supplemental oxygen and can dramatically improve exercise tolerance (40% experienced an 8 point drop in the St. George’s Respiratory Questionnaire at one year — while formoterol and tiotropium barely scored a 2-3 point drop in trials).
All that said, as authors point out, doctors seem reluctant to refer patients with severe COPD for a surgery that carries a 1 in 50 chance of death at 30 days. Experimental, less invasive bronchoscopic approaches have been favored recently, although none has yet been proven beneficial in large randomized trials.
Criner GJ et al. The National Emphysema Treatment Trial (NETT) Part II: Lessons Learned about Lung Volume Reduction Surgery. Am J Respir Crit Care Med 2011;184:881-893.