Paper: Ost DE, et al. Therapeutic Bronchoscopy for Malignant Central Airway Obstruction: Success Rates and Impact on Dyspnea and Quality of Life. Chest. 2014 Oct 30. [Epub ahead of print] PMID: 25358019
Question: Does therapeutic bronchoscopy improve symptoms and quality of life in patients suffering from malignant central airway obstruction (CAO)?
Design: A multicenter retrospective study of prospectively collected registry data on patients undergoing therapeutic bronchoscopy for malignant central airway obstruction using the American College of Chest Physicians (ACCP) Quality Improvement Registry, Evaluation, and Education (AQuIRE) program
Follow-up period: 30 days
Setting: 15 centers in the US.
Patients: 947 patients (mean age 62.8 y, 55% men, baseline Borg score of 3.6) underwent a primarily elective (68.8%) procedure(s) for central airway obstruction for a total of 1,115 procedures. Primary lung cancer diagnosis (78.2%) was given in majority of patients. Main comorbidities included: cardio-vascular disease (50.8%), COPD (30.4%) and diabetes (15.7%). Thirty seven percent of patients had ASA scores > 3. Forty percent of patients had disease located in the right main stem and 37.3% had left main stem disease. Eighty six percent of patients underwent procedures under general anesthesia with neuromuscular paralysis and volume cycled ventilation. Sixty five percent of patients underwent rigid bronchoscopy and 34.3% underwent flexible bronchoscopy. There was even distribution in terms of variety of ablative techniques used and types of stents placed for palliative of CAO.
Intervention: Flexible or rigid bronchoscopy for malignant CAO. CAO was defined as occlusion of >50%of the trachea, mainstem bronchi, bronchus intermedius or a lobar bronchus. All clinical decision making including type of interventions used were left at the discretion of the attending bronchoscopist. Technical success was defined as reopening the airway lumen to >50% of the normal diameter as subjectively estimated on bronchoscopy.
Outcomes:Technical success was achieved in 93% of procedures. Center success rates ranged from 90% to 98% in terms of achieving technical success (p=0.02). Endobronchial obstruction and stent placement were associated with success while ASA >3, renal failure, primary lung cancer, left mainstem disease, and tracheoesophageal fistula were associated with failure. Clinically significant improvements in dyspnea occurred in 90 of 187 patients measured (48%). Greater baseline dyspnea was associated with greater improvements in dyspnea while smoking, having multiple cancers, and lobar obstruction were associated with smaller improvements. Clinically significant improvements in HRQOL occurred in 76 of 183 patients measured (42%). Greater baseline dyspnea was associated with greater improvements in HRQOL while lobar obstruction was associated with smaller improvements.
Bronchoscopy for restoring airway patency in malignant CAO is mostly a palliative intervention. It may prolong life for some patients by allowing them to be liberated from the ventilator but the majority of patients benefit from changes in quality of life rather than duration (1). Thus, measurement of health utility and quality of life outcomes is a relevant part of cost effectiveness and risk analysis in therapeutic bronchoscopy just as is in other health care domains. Health utility can be measured by several preference-based utility measures, of which the EuroQol (EQ-5D) (2,3), the Health Utility Index (4) and the SF-6D have been used in trials (5,6). Up to date, a few studies have addressed effectiveness and utility of palliative intervention provided by alleviation of central airway obstruction (7-10). Majority of the studies have focused on effectiveness of a single modality or treatment vs another and health related quality of life (HRQOL) data has been sparse. The study by Ost et al showed that palliative interventions, albeit in the centers of excellence, tend to be successful 93% of the time, when success is defined as ability to improve airway patency. Statistically significant variations were present, however, between all procedures such as: location of care, types of anaesthesia used, ablative techniques utilized, decision to place a stent and types of stents placed. Secondary outcomes, measured in change from baseline of the Borg dyspnea score and HRQOL measured in single index measure SF-6D, found that 42% of patients had a clinically significant improvement in utility and 48% of patients had clinically and statistically significant improvement in dyspnea. On multivariate predictive analysis Zubrod score greater than one, not having extrinsic airway compression, and flexible bronchoscopy were associated with clinically significant improvements in utility. Alternatively, ASA>3 and Zubrod >1 were associated with statistically significant complications (p=.02). Overall complications rate was 3.9%, however there was statistically significant variation among centers in regards to the complications rates. Thirty-day mortality was 14.8%.
This study’s conclusions suggest that palliative interventions for malignant CAO should be considered even for traditionally labelled “high-risk” patients. In addition, it raises several important questions in terms of procedure utility and effectiveness as measured by HRQOL. It is interesting, however, that although the success rate in restoring airway patency was achieved in > 90% of patients, dyspnea and HRQOL improved in less than half of the treated patients. There may be various explanations for this discrepancy but one that comes to mind is our inability to predict which patients will respond to the palliative intervention. The study by Ost is hypothesis generating. For instance, based on these findings, patients with mild dyspnea or lobar obstruction may not warrant interventions, although technically these procedures may be feasible, safely performed and bronchoscopically considered warranted and successful.
By nature of registry based data collection, the decision making process was left to the attending bronchoscopist. Significant variations were seen between centers in terms of modality used, deployment of stents, mode of anesthesia and procedure choice. Moreover, as was shown by previous studies, disagreement exist among providers on the presence of >50% CAO (9), suggesting that providers may choose widely different times to intervene based on their assumption that the degree of stenosis has reached a critical point. This difference in decision-making process may significantly impact the outcome of what was considered success as well as potential utility and effectiveness of the procedures chosen. As the authors point out themselves, one needs to utilize a degree of caution when interpreting covariate data of this study and applying it over a wide range of patients.
The real strength of this study lies in its intent to explore clinical effectiveness and comparative effectiveness of bronchoscopic interventions in CAO. The authors do so by measuring utility with an SF-6D single measure index and a dyspnea score. Furthermore, this utility index may be used in calculating quality adjusted life year (QALYs), which following the guidelines of the National Institute of Health and Clinical Excellence has been recognised as the most important indicator of the effectiveness of health care interventions and a valid measure of disease burden. (11). QALY is also a measure of the value of health outcomes. Since health is a function of length of life and quality of life, QALY was developed as an attempt to combine the value of these attributes into a single index number. However, no single measure unit is ideal when measuring clinical utility of medical intervention and hence QALY analysis may undervalue treatments which benefit the elderly or others with a lower life expectancy (12). The study by Ost et al is one of the largest studies to date that attempts to measure clinical effectiveness of palliative intervention and weighs it against the risk of potential complications, risk of death and benefit of success.
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Katarine Egressy, MD, MPH
Interventional Pulmonology Fellow
University of Chicago