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Houston, TX
Dr. Lunn is affiliated with the Department of International Pulmonology, Baylor College of Medicine.
Correspondence to: William W. Lunn, MD, FCCP, Baylor College of Medicine, 1709 Dryden Road, Suite 950, Houston, TX 77030; e-mail: wlunn{at}bcm.tmc.edu
Cart Before the Horse?
COPD is a significant and growing challenge in the United States and throughout the world. It is difficult to interpret prevalence data, primarily due to varying definitions of COPD. It has been estimated that 2 to 10 million patients in the United States have the disease.1 COPD is currently the fourth-leading cause of death in the United States; and, in 2000, the World Health Organization reported there were 2.74 million deaths worldwide due to COPD.2 The human and economic impact of COPD is staggering. Patients with severe disease are often disabled, relying on family members and other caretakers for assistance with activities of daily living. These patients report quality-of-life scores on par with patients with AIDS and terminal cancer.3 It is estimated that the direct and indirect costs of COPD total $36.1 billion annually in the United States.4 Despite advances in care, treatment of COPD remains supportive and we are often unable to alter a relentless progression of disease.
In the 1950s, Brantigan and Mueller5 sought to relieve dyspnea in their COPD patients by correcting the overinflation of the chest by surgically removing lung tissue. Approximately 75% of patients having "reduction pneumoplasty" reported relief of symptoms of dyspnea. While these investigators were praised for their innovation, they were criticized for the lack of an objective means of determining improvement and an 18% perioperative mortality rate. Widespread enthusiasm for the volume reduction concept was kindled by Cooper and Patterson6 in the 1990s, who modified Brantigan’s surgical technique and reported very favorable results with an acceptable rate of morbidity and mortality. Hospitals around the United States began performing lung volume reduction surgery (LVRS) with varied results, including an overall perioperative mortality rate approaching 17%.3 In 1995, after an Agency for Healthcare Research and Quality investigation of LVRS concluded that there was no clear benefit to patients, the Healthcare Financing Administration announced that Medicare would not pay for LVRS. The ensuing political firestorm lead to the creation of the National Emphysema Treatment Trial (NETT),7 a multicenter, randomized, controlled trial comparing LVRS to medical therapy. The results from the NETT7 were mixed: while there was no benefit in survival, the surgical patients did have significantly improved exercise capacity and quality-of-life scores. The 90-day mortality rate was 7.9% in the surgical group and 1.3% in the medical group. However, the cost-effectiveness of LVRS therapy was deemed unfavorable.8 Subgroup analyses from the NETT sought to identify the ideal candidate for LVRS. The significance of NETT subgroup analyses and the proper role of LVRS was, and continues to be, hotly debated. Nevertheless, in 2004, the Centers for Medicare and Medicaid Services announced that Medicare would cover LVRS, performed in approved centers, for the following groups: (1) patients with low exercise capacity and either upper- or lower-lobe predominant disease; and (2) patients with high exercise capacity and upper-lobe disease.
Currently, there is a great deal of interest in new and developing technologies that allow physicians to perform endoscopic LVRS (ELVRS).910 The devices receiving most attention are endobronchial valves that are placed via a bronchoscope. The valves are placed in targeted lobes with the aim of causing atelectasis, thereby reducing the volume of the thoracic cavity, and restoring a more favorable alignment of the respiratory muscle system. The hope is that patients undergoing ELVRS may achieve all of the benefit that surgical patients in the NETT achieved with very little risk. In this issue of CHEST (see page 518), Wan and colleagues11 report their experience using endobronchial valves to perform ELVRS in patients with radiographic evidence of heterogeneous disease and persistent dyspnea despite maximal medical therapy. Their study was a multicenter trial, with nine centers participating from seven countries. All patients underwent ELVRS, and the baseline data were employed to determine if ELVRS was beneficial. Study end points included change in FEV1, FVC, residual volume, and exercise tolerance as assessed by a 6-min walk test. Results are reported up to 90 days after ELVRS was performed. The most significant changes were a 10.7% overall improvement in FEV1 and a 23% improvement in exercise capacity. Comparing these results to those of the NETT is difficult for the following reasons: (1) the NETT reported results from 6 months, 12 months, and 24 months; (2) improvements in FEV1 and exercise tolerance decreased over time in the NETT; and (3) NETT results were reported in histograms for patient groups. The NETT, for example, reported that 65% of patients in the surgical group had an improvement in FEV1 6 months after LVRS and that improvement averaged approximately 11%. Wan et al11 report that 8 of their 98 patients (8.2%) had serious complications: death, n = 1; pneumothorax requiring surgery, n = 3; and prolonged air leak, n = 4. Additionally, the authors observed other complications in 30 patients, including 5 pneumonias and 17 exacerbations of COPD. Finally, the authors performed a subset analysis and noted that patients treated with valves targeting one lobe or valves placed unilaterally achieved better results than the others.
Wan et al11 deserve accolades for conceiving and performing this investigation. Their study has several merits. First, it is the largest series of ELVRS reported to date. Prior studies have been small, observational series looking at the feasibility of the procedure. Second, the authors chose objective, physiologic outcome measures rather than the more subjective quality-of-life questionnaires as study end points. This increases the impact of their findings. Third, the study demonstrates that ELVRS can be done safely, with an acceptable complication rate, in centers with expertise in pulmonary endoscopy. Finally, it suggests that patients undergoing ELVRS may achieve real and significant improvements in pulmonary function after the procedure.
However, while the observations of Wan et al11 are intriguing, a few caveats are in order. First, it is very difficult to interpret the results of this study since there was no control group. Indeed, it may be time to change our approach to creating a control group in these studies. In 2002, Moseley et al12 reported their experience performing arthroscopic debridement, arthroscopic lavage, or a placebo procedure on 165 consecutive patients with osteoarthritis of the knee. All three groups experienced similar complications and rates of improvement of symptoms, with no procedure demonstrating superiority. Performing a sham endoscopy procedure in an ELVRS study might be the most effective manner to create a meaningful control group. Second, an analysis of subsets in this study to identify the ideal technique or candidates for ELVRS seems premature.
Despite all of its promise, and all of our enthusiasm, we are not yet certain if ELVRS is truly effective. Indeed, a multicenter, randomized, controlled trial of another endobronchial valve for ELVRS is currently underway. Let us await the results of this trial before further efforts are made to identify the ideal candidate, device, or technique for ELVRS.
Footnotes
Dr. Lunn has no conflict to disclose.
References
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