Figure 1.

National Emphysema Treatment Trial (NETT) subgroup treatment effects. Effect of lung volume reduction surgery (LVRS) versus medical treatment on mortality, maximal workload achieved on cardiopulmonary exercise testing (improvement of more than 10 W vs. not improved), and disease-specific quality of life as measured by the St. George's Respiratory Questionnaire (SGRQ; improvement of more than 8 units in total score vs. not improved). OR = odds ratio; RR = relative risk; *Patients not considered candidates for LVRS by the NETT or approved for LVRS by the Centers for Medicare and Medicaid Services or the Joint Commission on Accreditation of Healthcare Organizations.