Outcomes of Updated Evaluation of the Cost-effectiveness of Lung Volume Reduction Surgery
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).
As noted, post hoc analyses suggested differential benefits from LVRS based on the presence or absence of upper-lobe predominance in the distribution of emphysema on CT and low or high maximal exercise capacity after pulmonary rehabilitation. Patients with predominantly upper-lobe emphysema and low exercise capacity had the most favorable cost-effectiveness ratio for surgery ($77,000 per QALY gained). The other subgroups had far less favorable cost-effectiveness (Table 3). The cost-effectiveness acceptability curves revealed moderate uncertainty for the overall group and the upper-lobe plus low exercise capacity subgroup but high levels of uncertainty for the other two subgroups (Fig 1).
Projected Results at 10 Years
Based on extrapolations for survival and cost, the projected overall cost-effectiveness of LVRS at 10 years was $54,000 per QALY gained. The cost-effectiveness ratios were more favorable for each subgroup (Table 3), but uncertainty analysis (as displayed by the cost-effectiveness acceptability curves) revealed high degrees of uncertainty around the point estimates (Fig 2).
Comparison of Initial and Final Observed and Projected Results
Comparison of actual and projected results using the earlier and most recent data reveals some important differences in the cost-effectiveness analysis of LVRS that emphasize the limitations of interim analysis and projections of shorter-term follow-up. Our previous analysis2 showed an overall cost-effectiveness ratio of $190,000 per QALY at 3 years for LVRS vs medical therapy, and a projected ratio of $58,000 per QALY at 10 years. Using the extended follow-up period, the observed cost-effectiveness of LVRS improved, consistent with the trend toward improvement over time observed in the projections (Table 3). Compared to the 10-year projections using 3 years of follow-up data, the projected results using the extended follow-up data revealed similar results for the overall cohort but markedly different results for the subgroups. The 10-year projected outcome for one subgroup—non-upper-lobe-predominant emphysema and low exercise capacity—changed dramatically from initially suggesting lower costs and better outcomes for surgery to now showing $80,000 per QALY gained when 5-year data are available. Uncertainty remained high for both analyses.
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Figure 1. Five-year cost-effectiveness acceptability curves for LVRS vs medical therapy for all patients and for three subgroups with significantly improved clinical outcomes in the LVRS arm (either reduced mortality, improved quality of life, or both). The curve represents the probability that LVRS is associated with a cost per QALY gained that is lower than the corresponding cost-effectiveness ratios displayed on the x-axis. The value of the ceiling ratio at a probability of 0.5 is the median cost per QALY for LVRS. Solid horizontal lines denote 95% confidence limits for the projections.
Figure 2. Ten-year cost-effectiveness acceptability curves for LVRS vs medical therapy for all patients and for three subgroups with significantly improved clinical outcomes in the LVRS arm (either reduced mortality, improved quality of life, or both). The curve represents the probability that LVRS is associated with a cost per QALY gained that is lower than the corresponding cost-effectiveness ratios displayed on the x-axis. The value of the ceiling ratio at a probability of 0.5 is the median cost per QALY for LVRS. Solid horizontal lines denote 95% confidence limits for the projections.
Table 1—Characteristics of 1,066 Patients Included in the Cost-effectiveness Analysis From the NETT
(n = 531)
Medical Therapy Group
(n = 535)
|Mean age at randomization, yr||67.0 ± 6.2||67.1 ± 5.8|
|Race or ethnic group|
|Non-Hispanic white||506 (95.3)||506 (94.6)|
|Non-Hispanic black||17 (3.2)||18 (3.4)|
|Female||232 (43.7)||196 (36.6)|
|Male||299 (56.3)||339 (63.4)|
|Average daily QWB scorej||0.58 ± 0.12||0.57 ± 0.11|
Table 2—Total Health-Care-Related Costs and QALYs With Observation Up to 5 Years After Randomization Overall and Among Subgroups of Patients Defined by Baseline by Distribution of Emphysema and Exercise Capacity
|Variables||LVRS Group||Medical Therapy Group||p Value|
|Mean||95% CI||Mean||95% CI|
|No. of patients||531||535|
|Total costsf||$136,997||$127,329-$146,664||$100,153||$91,199-$109,106||< 0.001|
|Upper-lobe emphysema and low exercise capacity!|
|No. of patients||137||148|
|Total costsf||$152,368||$132,143-$172,593||$99,023||$84,218-$113,829||< 0.001|
|Upper-lobe emphysema and high exercise capacity!|
|No. of patients||204||212|
|Non-upper-lobe emphysema and low exercise capacity!|
|No. of patients||82||65|
Table 3—Projected and Observed Cost-effectiveness Ratios for LVRS vs Maximal Medical Therapy for Observed and Projected Years of Follow-up From Initial Randomization, Using Observations Up to 3 Years and 5 Years After Randomization
|Incremental Cost-effectiveness Ratio*||
|Upper-Lobe Emphysema, Low Exercise Capacity*||Upper-Lobe Emphysema, High Exercise Capacity*||
Non-Upper-Lobe Emphysema, Low Exercise Capacity*
|Observed up to 3 yr||$190,000||$98,000||$240,000||$330,000|
|Observed up to 5 yr||$140,000||$77,000||$170,000||$225,000|
|Projected at 10 yr based on 3 yr of follow-up!||$58,000||$21,000||$54,000||Dominant§|
|Projected at 10 yr based on 5 yr of follow-up!||$54,000||$48,000||$40,000||$87,000|