Racial Differences in Waiting List Outcomes in Chronic Obstructive Pulmonary Disease; D. J. Lederer, E. K. Benn, R. G. Barr, J. S. Wilt, G. Reilly, J. R. Sonett, S. M. Arcasoy, S. M. Kawut (Am J Respir Crit Care Med. 2007; Nov 15; [Epub ahead of print]).
Rationale. Blacks with chronic illness have poorer outcomes than Whites in the United States. The health outcomes of minorities with chronic obstructive pulmonary disease on the lung transplant waiting list have not been studied.
Objective. To compare outcomes of Black and White patients with chronic obstructive pulmonary disease after listing for lung transplantation in the United States.
Methods. Retrospective cohort study of all 280 non-Hispanic Black and 5,272 non-Hispanic White adults > / = 40 years old with chronic obstructive pulmonary disease listed for lung transplantation in the United States between 1995 and 2004.
Measurements and main results. Blacks with chronic obstructive pulmonary disease were more likely to have pulmonary hypertension, obesity, and diabetes; to lack private health insurance; and to live in poorer neighborhoods than Whites. Blacks were less likely to undergo transplantation after listing compared to Whites, despite adjustment for age, lung function, pulmonary hypertension, cardiovascular risk factors, insurance coverage, and poverty level (adjusted hazard ratio = 0.83, 95% confidence interval 0.70 to 0.98, p = 0.03). This was accompanied by a greater risk of dying or being removed from the list among Blacks (unadjusted hazard ratio = 1.31, 95% confidence interval 1.05 to 1.63, p = 0.02).
Conclusions. Following listing for lung transplantation, Black patients with chronic obstructive pulmonary disease were less likely to undergo transplantation and more likely to die or be removed from the list compared to White patients. Unequal access to care may have contributed to these differences.
Comments. While the results of this study are not likely to be of great surprise to most I do think it is useful for researchers and clinicians alike to appreciate that many of the issues pertaining to the phenomenon of so called “urban asthma” also are germane to the observations made with regard to COPD in certain ethnic and racial minorities. Not only co-morbidities and possible genetic factors but clearly socioeconomic status and access to care and quality of care are major issues as this study not only adjusted for co-morbidities and severity of disease but also for insurance coverage and poverty level. Hopefully, these investigators will take the findings from their retrospective review and study this in a prospective fashion to further elucidate the factors leading to the disparity noted and how to address it.
Mechanisms of Dyspnea During Cycle Exercise in Symptomatic Patients with GOLD Stage I COPD; D. Ofir, P. Laveneziana, K. A. Webb, Y. M. Lam, D. E. O'Donnell, Canada (Am J Respir Crit Care Med. 2007; Nov 15; [Epub ahead of print]).
Rationale. Smokers with a relatively preserved forced expiratory volume in one second (FEV1) may experience dyspnea and activity limitation but little is known about underlying mechanisms.
Objectives. To examine ventilatory constraints during exercise in symptomatic smokers with GOLD stage I COPD so as to uncover potential mechanisms of dyspnea and exercise curtailment.
Methods. We compared resting pulmonary function and ventilatory responses (breathing pattern, operating lung volumes, pulmonary gas exchange) to incremental cycle exercise as well as Borg scale ratings of dyspnea intensity in 21 patients (post-bronchodilator FEV1 91 ±7% predicted and FEV1/FVC 60 ± 6%; mean ± SD) with significant breathlessness and 21 healthy age- and gender-matched control subjects with normal spirometry. Results: In COPD compared with control, peak oxygen consumption and power output were significantly reduced by more than 20% and dyspnea ratings were higher for a given work rate and ventilation (p < 0.05). Compared with the control group, the COPD group had evidence of extensive small airway dysfunction with increased ventilatory requirements during exercise, likely on the basis of greater ventilation-perfusion abnormalities. Changes in end-expiratory lung volume during exercise were greater in COPD than in health (0.54 ± 0.34 vs 0.06 ± 0.32 L, respectively; p < 0.05) and breathing pattern was correspondingly more shallow and rapid. Across groups, dyspnea intensity increased as ventilation expressed as a percentage of capacity increased (p < 0.0005) and as inspiratory reserve volume decreased (p < 0.0005). Conclusion: Exertional dyspnea in symptomatic patients with mild COPD is associated with the combined deleterious effects of higher ventilatory demand and abnormal dynamic ventilatory mechanics, both of which are potentially amenable to treatment.
Comments. The group from Queen's University have been at the forefront of studying the role of dynamic hyperinflation in patients with COPD. In this study they demonstrate that even patients with mild COPD can develop hyperinflation with exercise and that this is largely a result of small airway disease. While many clinicians may think it excessive to order full PFT's, exercise testing and CT scans for patients with mild COPD, this study shows that it is quite likely the patient's COPD that is leading to their exercise intolerance despite a well preserved FEV-1. The authors have outlined not only the issues of ventilatory mechanics but also the increased ventilatory demand that in mild COPD patients is likely related to increased oxygen requirement for any given workload.
Effect of Occupational Exposures on Decline of Lung Function in Early Chronic Obstructive Pulmonary Disease P. Harber, D. P. Tashkin, M. Simmons, L. Crawford, E. Hnizdo, J. Connett (Am J Respir Crit Care Med. 2007 Nov 15; 176(10):994–1000. Epub 2007 Jul 12)
Rationale. Several occupational exposures adversely affect lung function.
Objectives. This study reports the influence of continued occupational dust and fume exposures on the rate of decline of lung function in participants with early chronic obstructive pulmonary disease (COPD) studied in a population-based study. Methods. Subjects consisted of 5,724 participants in the Lung Health Study, a multicenter study of smoking cessation and anticholinergic bronchodilator administration in smokers with early COPD (3,592 men; 2,132 women). Average post-bronchodilator FEV1 at entry was 78.4% predicted for men and 78.2% predicted for women; all participants had an FEV1/FVC ratio less than 0.70.
Measurements and main results. Participants underwent a baseline evaluation and 5 annual follow-up assessments, including questionnaires and spirometry. The effect of ongoing dust or fume exposure on FEV1 in each follow-up year was statistically evaluated with a mixed-effects regression model, which was adjusted for FEV1 at entry, age, airway responsiveness to methacholine, baseline smoking intensity, and time-varying (yearly) smoking status during each follow-up year. In men with early COPD, each year of continued fume exposure was associated with a 0.25% predicted reduction in post-bronchodilator FEV1% predicted. Continued smoking and airway hyperresponsiveness were also associated with reduction in FEV1 during each year of follow-up in both men and women. Statistically significant effects of dust exposure on the rate of decline were not found, nor were effects of fume exposure noted in women.
Conclusions. These results suggest a need for secondary prevention by controlling occupational fume exposures.
Comments. Clearly the identification of a group of COPD subjects carries selection bias in addressing the issue of the effects of occupational exposures to fumes and dust. In spite of this, the study by Harber et al shows that individuals who develop COPD as a result of cigarette smoking are also likely to be more susceptible than the general population to the effects of fumes and various dust exposures. The study illustrates the importance of not underestimating the contribution of occupational exposures and the need to vigilant in making enquires with regard to such fume exposures and reduce or eliminate them as much as possible. The differences between dust and fume exposure and the lack of effects in women are interesting and warrant further study.
Comprehensive Pulmonary Rehabilitation for Anxiety and Depression in Adults with Chronic Obstructive Pulmonary Disease: Systematic Review and Meta-Analysis; P. A. Coventry, D. Hind (J Psychosom Res. 2007 Nov; 63(5):551-565).
Objectives. To estimate the clinical effect of pulmonary rehabilitation (with or without education) on anxiety and depression in patients with chronic obstructive pulmonary disease (COPD). Secondary outcomes were generic and disease-specific health-related quality of life (HRQOL).
Methods. Systematic review and meta-analysis of primary outcomes to calculate mean change effect sizes [standardized mean difference (SMD)] and associated 95% CIs.
Results. Six randomized controlled trials (RCTs) that compared pulmonary rehabilitation with standard care (with or without education) were included in the review. Three studies (n = 269) showed that comprehensive pulmonary rehabilitation was significantly more effective than standard care in reducing short-term anxiety (SMD = −0.33, 95% CI: −0.57 to −0.09, p =. 008) and depression (SMD = −0.58, 95% CI: −0.93 to −0.23, p =. 001). Education alone and exercise training alone were not associated with significant reductions in either anxiety or depression. When compared with standard care, comprehensive pulmonary rehabilitation was also associated with short-term significant gains in both disease-specific and generic HRQOL. Studies that included long-term follow-up data showed that gains in both psychological health status and HRQOL were not sustained at 12 months.
Conclusions. Rehabilitation programmes that include up to three sessions per week of incremental and supervised exercise, along with education and psychosocial support, significantly reduce anxiety and depression more than standard care in patients with COPD. Further research should focus on exploring effective and acceptable maintenance strategies along with evaluations of stepped care approaches for the management of psychological co-morbidity, especially among those with severe anxiety and depression.
Comments. The Psycho-Social impact particularly with regard to depression and anxiety associated with COPD is gaining attention. This study outlines its prevalence and the benefits of rehabilitation programs in addressing this issue. Cardiopulmonary Rehabilitation continues to be underutilized for patients with COPD and should be considered sooner than later. Clinicians' early identification of depression and anxiety issues and referral to behavioral medicine and/or pulmonary rehabilitation are important in delivering comprehensive care to COPD patients.
Air Travel Hypoxemia Versus the Hypoxia Inhalation Test in Passengers with Chronic Obstructive Pulmonary Disease P. T. Kelly, M. P. Swanney, L. M. Seccombe, C. Frampton, M. J. Peters, L. Beckert (Chest 2007; Nov 7; [Epub ahead of print]).
Background. Limited data is available comparing air travel with the hypoxia inhalation test (HIT) in passengers with COPD. The aim of this study was to assess the predictive capability of the HIT to in-flight hypoxemia in passengers with COPD. Methods Thirteen passengers (7 females) with COPD (mean ± SD FEV(1)/FVC; 44 ± 17%) volunteered for this study. Respiratory function tests were performed pre-flight. Pulse oximetry, cabin pressure and dyspnea were recorded in-flight. A HIT and 6-minute walk test were performed post-flight. In-flight oxygenation response was compared to the HIT and respiratory function parameters. Results: All subjects flew without oxygen and no adverse events were recorded in-flight (mean cabin altitude 2165 m; range 1892–2365 m). Air travel caused significant desaturation (pre-flight: 95 ± 1%; in-flight 86 ± 4%), which was worsened by activity (nadir SpO(2) 78 ± 6%). The HIT caused comparable desaturation to air travel (84 ± 4%). In-flight PIO(2) was higher than the HIT PIO(2) (113 ± 3 mmHg versus 107 ± 1 mmHg; p < 0.001). The HIT SpO(2) showed the strongest correlation with in-flight SpO(2) (r = 0.84, p < 0.001). Conclusion Significant in-flight desaturation can be expected in passengers with COPD. The HIT compared favorably with air travel, with differences explainable by PIO(2) and physical activity. The HIT is the best widely available laboratory test to predict in-flight hypoxemia.
Comments. Clinicians are often unclear as to how to estimate oxygen requirements for COPD patients contemplating air travel. The authors demonstrate that many COPD patients indeed have significant desaturation episodes during air flight despite meeting current recommendations (preflight PaO2 of 70 mmHg or more on room air is predictive of maintaining a PaO2 of greater than 55 mmHg in flight) to not require supplemental oxygen during air travel. The HIT study is performed by giving patients a 15%/85% (O2/Nitrogen) mix for 20 minutes and recording their oxygen saturations. It does not incorporate an exercise or activity component.
This patient cohort was quite severe with a low mean FEV1 of 0.99 L and DLCO 56% predicted, but they did not demonstrate evidence of CO2 retention. The HIT seemed to reasonably predict in-flight hypoxemia, and indeed most participants experienced significant hypoxemic episodes during the cruise portion of their flights, particularly with activity. It is noteworthy that no participant in this study seemed to suffer adverse events, although the sample size was small. This is an issue given that many airlines prohibit in-flight oxygen and many patients who are advised to use oxygen have to fly with alternative carriers often at higher cost. Hence it is reasonable to perform the HIT so that doctors can have a more informed discussion about potential risks for their patients with COPD who are considering air travel with or without supplemental oxygen.