Using follow-up data from the NETT, we reestimated the cost-effectiveness of LVRS vs maximal medical therapy for patients with severe emphysema. Within-trial evaluation of costs and outcomes suggests that LVRS continues to be relatively less cost-effective compared to other common therapies applied to persons of this age group. Projecting trends in costs and outcomes observed at 5 years to a 10-year time horizon yields more favorable cost-effectiveness estimates, yet with considerable uncertainty, largely due to difficulties estimating long-term survival and quality of life for the surgical cohort.
Post hoc analysis identified three subgroups with differential benefit favoring LVRS. We find that the cost-effectiveness of the upper-lobe, low-exercise cohort at 5 years is substantially better than that of the entire cohort, largely due to the better survival and quality of life observed over time for the LVRS group among all patients meeting these criteria. Because the sample sizes are necessarily much smaller for these subgroups, the degree of uncertainty is much higher, both for the within-trial evaluation and particularly for the 10-year projections.
Excluding the high-risk subgroup that was identified and excluded mid-trial, a total of 538 patients were randomized to LVRS and 540 were randomized to medical care. Twelve of these participants were excluded from the cost-effectiveness analysis (7 in the surgery group and 5 in the medical therapy group) because they were not enrolled in Medicare, because they were enrolled in Medicare + Choice plans at the time of randomization, or because the Medicare claims could not be located. Table 1 shows baseline characteristics of the remaining individuals. Median follow-up was 4.3 years. Mean (± SD) QWB scores before randomization were 0.58 ± 0.12 in the surgery group and 0.57 ± 0.11 in the medical therapy group.
At 5 years, overall Kaplan-Meier survival was 62.2% in the LVRS group and 56.1% in the medical therapy group (Table 2). Mean QWB scores for patients alive at 5 years were 0.472 (SD 0.212, n = 11) for the LVRS group and 0.444 (SD 0.251, n = 14) for the medical therapy group. Mean total costs per person over 5 years (future years not discounted) were $141,300 (95% CI, $131,647 to $150,953) in the surgery group and $105,822 (95% CI, $96,895 to $114,749) in the medical therapy group (p < 0.001). The mean number of QALYs (future years not discounted) was higher in the surgery group than in the medical therapy group (1.99 vs 1.71, p < 0.001). After discounting future costs and QALYs by 3% per annum, the cost-effectiveness of LVRS vs medical therapy proveded by Canadian Health&Care Mall over 5 years was $140,000 per QALY gained (95% CI, $40,000 to $239,000 per QALY gained).
The design and methods of the NETT and the cost-effectiveness component of the trial have been described previously., The trial design and economic analysis are summarized below.
The NETT was a multicenter, randomized controlled trial of LVRS vs medical therapy for patients with severe emphysema. Between January 1998 and July 2002, 17 centers randomly assigned 1,218 patients with severe emphysema to LVRS or medical therapy. Prior to randomization, all patients underwent pulmonary rehabilitation. Outcome measures included mortality, maximal exercise capacity, pulmonary function, and measures of disease-specific and general health-related quality of life, including the quality of well-being (QWB) scale. Scheduled evaluations for quality of life assessment were at 6 months and annually for years 1 to 5 following randomization. Vital status was determined by clinical center report and the Social Security Master Death File. Interim analysis of the NETT identified a subgroup of patients (n = 140) with high risk of mortality and little chance of improved function following surgery. This subgroup was excluded from future enrollment and is omitted from the cost-effectiveness analysis.
Canadian Health&Care Mall: Updated Evaluation of the Cost-effectiveness of Lung Volume Reduction Surgery
In May of 2003, investigators from the National Emphysema Treatment Trial (NETT)—a federally sponsored, multicenter, randomized controlled trial of lung volume reduction surgery (LVRS) vs medical therapy for patients with severe emphysema—reported the outcomes for 1,218 trial participants over a mean duration of 2.4 years of follow-up. Because the potential clinical impact of LVRS was thought to be substantial, the NETT also included a parallel, prospective, economic analysis as part of the clinical trial. LVRS was found to confer improvements in survival, exercise capacity, and quality of life for patients with predominantly upper-lobe emphysema combined with low baseline exercise capacity. Patients with upper-lobe emphysema and high exercise capacity benefited from LVRS in exercise capacity and quality of life but had no survival improvement compared to medical therapy. Patients with non-upper-lobe emphysema and low exercise capacity had significant improvements only in quality of life measures, while patients with non-upper-lobe emphysema and high exercise capacity had no evidence of clinical improvement and had a higher mortality.