Endobronchial valve vs. lung volume reduction surgery, unconvinced

This is a retrospective study using the United States (US) Centers for Medicare and Medicaid Services Inpatient Claims Database comparing lung volume reduction surgery (LVRS) and endobronchial valve (EBV) placement in patients with advanced emphysema (1). The primary outcome was mortality at 30 days and up to 3 years. There were multiple secondary outcomes mostly analyzing cost, readmission, or complications.

Unfortunately, I believe there are several methodological problems which make me skeptical of these results. Let us start with the unadjusted outcomes. Although EBV is considered a less invasive and less morbid procedure, this study shows the 30 day outcomes all favored LVRS except for length of stay (Tab. 2 of the commented article). One very surprising finding was the all-cause mortality rate. EBV had a higher mortality rate at 7.37% vs. 4.63% for LVRS. This is higher than the mortality rates seen in randomized EBV trials including STELVIO 3.1% mortality at 12 months (2), IMPACT 0% mortality at 12 months (3), TRANSFORM 1.5% mortality within 30 days, and LIBERATE 3.1% mortality within 30 days (4). This also contrasts with a recent paper looking at the National Inpatient Sample which found that the number of in-hospital deaths was <2.3% (4). This also contrasts with the randomized, controlled CELEB trial which showed a 2.9% and 2.2% mortality rate at 1 year for LVRS and EBV respectively (5). The mortality rate is so high in the Hayanga et al. analysis that I wonder if some of the patients had valves placed for persistent air leaks rather than for volume reduction. For example, in the above cited paper by Filho et al., the authors excluded all patients in whom EBV placement occurred after hospital day 1 to avoid counting patients who underwent EBV implantation for persistent air leak (3). This was not part of the methods in the referenced paper by Hayanga et al. Including patients who had EBV for persistent air leaks would explain this increased 30 day mortality.

The other risk factor not sufficiently addressed is coronavirus disease 2019 (COVID-19). The data was harvested between January 2018 and December 2020 which would have included a year of the COVID-19 pandemic. Patients were excluded if they had a history of lung cancer, connective tissue disease, pulmonary hypertension, bronchiectasis, fibrotic disease, or interstitial lung disease, however, COVID-19 infection was not specifically mentioned. It would be interesting to see if the mortality rate was higher during 2020 compared to 2018 and 2019. As an aside, the 4.6% 30 day mortality for LVRS is also higher than most series describe. The National Emphysema Treatment Trial non-high-risk group, for example, had a 30 day mortality of 2.2%. Other modern series report a 30 day mortality of 0–2.5% for LVRS (6). If this data is to be believed, it would suggest that real-world outcomes in the Medicare population are worse for both EBV and LVRS than the results seen in randomized trials and published case series.

Without the above concerns addressed, there is not a lot of need to go further, but there is one glaring concern with the risk adjustment. Elixhauser score was the only variable which factored into the risk adjustment, however, the EBV group had 50% use of supplemental oxygen vs. only 16% for the LVRS group (Tab. 1 of the commented article). This paper is specifically about patients with end-stage lung disease and so without other pulmonary function data, this finding makes it hard to assume that these were equal populations and at the very least, this risk factor needs to be included in the risk adjustment.

This is an important topic for research in order to provide patients with the best advice for treatment. As a practitioner of LVRS, I am very aware of its benefits and complications. As I do not place EBVs, I am not as familiar with EBV outcomes, however, diving into the details of these two database studies (1,4), I believe Filho et al. gives a more accurate picture of real-world (non-trial) EBV outcomes.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Current Challenges in Thoracic Surgery. The article has undergone external peer review.

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References

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