Figure 1.

Probability of reaching the composite event (CE) or mortality for the lung volume reduction surgery (LVRS) or medical treatment groups. Failure functions, shown as the proportion of patients developing the event over time, in the following samples of patients: (A) All patients in the study. (B) Patients without high risk of perioperative mortality. (C) Patients without high risk for perioperative mortality, upper-lobe–predominant emphysema, and high exercise capacity. (D) Patients without high risk for perioperative mortality, upper-lobe–predominant emphysema, and low exercise capacity. (E) Patients without high risk for perioperative mortality, non–upper-lobe predominant emphysema, and high exercise capacity. (F) Patients without high risk for perioperative mortality, non–upper-lobe predominant emphysema, and low exercise capacity. Solid lines relate to the composite event, which is the occurrence of death or the occurrence of at least an eight-point increase in the total score on St. George's Respiratory Questionnaire, whichever happened first. Gray solid lines represent the medical treatment group, and black solid lines represent the LVRS group. Dotted lines represent the previously reported results of survival analysis for the same sets of patients (n = 9) and are included for comparison. The P value in the upper left corner of each panel refers to the value found when Wilcoxon tests were used to compare the failure functions for the composite event in the medical treatment group with those in the LVRS group. The number at risk refers to the number at risk for the composite event. The failure functions are described for death alone and for the composite event.