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Journal of Cardiopulmonary Rehabilitation & Prevention:
doi: 10.1097/HCR.0000000000000057
Literature Update

Selected Abstracts From Recent Publications in Cardiopulmonary Disease Prevention and Rehabilitation

Kalra, Sanjay MD; Brubaker, Peter H. PhD

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Van Remoortel H, Hornikx M, Langer D, et al

Am J Respir Crit Care Med. 2014;189:30–38.

Rationale: There is little information about comorbidities and their risk factors in the preclinical stages of chronic obstructive pulmonary disease (COPD).

Objectives: This study aims to investigate the prevalence of premorbid risk factors and comorbid diseases and its association with daily physical activity in subjects detected with COPD by spirometry screening.

Methods: Sixty subjects with preclinical COPD (63 ± 6 yr; 68% [n = 41] male) were compared with 60 smoking control subjects (62 ± 7 yr; 70% [n = 42] male) and 60 never-smoking control subjects (62 ± 6 yr; 57% [n = 34] male). Comorbidities (cardiovascular, metabolic, and musculoskeletal disease) and daily physical activity (by multisensor activity monitor) were measured objectively.

Measurements and Main Results: The prevalence of premorbid risk factors and comorbid diseases was significantly higher in preclinical COPD compared with age-matched never-smoking control subjects, but was similar to smoking control subjects not suffering from COPD. In preclinical COPD and smoking control subjects, the combination of cardiovascular disease and musculoskeletal disease was the most prevalent (15% [n = 9] and 12% [n = 7], respectively). In a multivariate logistic regression analysis, physical inactivity and smoking were found to be independent risk factors for having greater than or equal to two comorbidities.

Conclusions: Premorbid risk factors and comorbid diseases were more prevalent in the preclinical stages of COPD and smokers without COPD. Physical inactivity and smoking were more strongly associated with the presence of comorbidities compared with airflow obstruction.

Editor's Comment: I find this an interesting study but possibly for quite different reasons from those used for carrying it out in the first place. The authors hypothesized that the presence of chronic obstructive pulmonary disease (COPD) would be an independent risk factor for all the burden of comorbid conditions that patients with COPD are recognized to carry. They used matched nonsmoking and smoking (but without COPD) controls and compared these to a group of subjects with newly diagnosed COPD. Why they choose to label these patients as having preclinical COPD, rather than new or recently diagnosed COPD, is not clear and one of the many areas that leave me quite unenthused about this study.

The results go against the study hypothesis; comorbid conditions were equally present in both smoking groups, with or without COPD. In fact, only smoking and physical inactivity correlated with the comorbidity burden, and the presence of airflow obstruction (ie, COPD) had no impact at all. Of course, these were patients with relatively mild COPD (GOLD Group A), and the impact of more severe COPD on the comorbid condition spectrum was not studied, something that may have had a greater likelihood of supporting the initial hypothesis. In addition, the small number of subjects studied (COPD, n = 60) really makes any binding conclusions hard to draw. What does stand out is the low prevalence of comorbid conditions in never-smokers, and that is not only biologically plausible but also already borne out by clinical experience. In the end, this study almost manages to hide the central role of smoking in disease pathogenesis by cluttering up even this simple message with layers of obfuscatory irrelevancies.—SK

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Parreira VF, Janaudis-Ferreira T, Evans RA, et al

Chest. Published online first January 2, 2014, doi: 10.1378/chest.13-2071.

Background: The incremental shuttle test (ISWT) was developed over twenty years ago and has been used to assess peak exercise capacity in a variety of chronic diseases. The aim of this systematic review was to describe the measurement properties of the ISWT in a clinical population.

Methods: Of 800 articles identified by electronic and hand searches, 35 articles were included. Twenty-one articles included data on validity of ISWT, 18 on reliability, four on responsiveness and four on interpretability.

Results: Most of the studies were conducted in patients with chronic obstructive pulmonary disease (n = 13) or cardiac disease (n = 8). For criterion validity, comparisons between distance covered during the ISWT and peak oxygen uptake reported correlations ranging from 0.67 to 0.95 (p < 0.01). For reliability, intra-class correlation coefficients for test-retest ranged from 0.76 to 0.99. The ISWT was shown to be responsive to pulmonary rehabilitation, and to bronchodilator administration. The minimal clinically important difference (MCID) in patients with chronic obstructive pulmonary disease was 48m. Predictive equations for the distance in the ISWT are available for healthy individuals.

Conclusion: The ISWT can be considered a valid and reliable test to assess maximal exercise capacity in individuals with chronic respiratory diseases. The ISWT has been shown to be responsive to PR and bronchodilator in individuals with COPD, cystic fibrosis and asthma. Further studies examining responsiveness and the MCID of the ISWT in patients with conditions other than lung diseases are required for the interpretation of interventions in other populations.

Editor's Comment: The incremental shuttle walk test (ISWT) falls in the somewhat ambiguous area between the 6-minute walk test (6MWT), an established and validated measure of effort tolerance with wide use in cardiac and pulmonary disease, and the classical maximal treadmill or cycle ergometer-based cardiopulmonary exercise test. It has gained little traction in the United States, where the aforementioned tests have long enjoyed ascendancy, but it has been widely used in European centers, especially in the United Kingdom, and often figures in clinical and research reports from there.

The current meta-analysis identified 21 studies that met its requirements, with 13 focused on pulmonary disease (10 on chronic obstructive pulmonary disease and 3 on other lung diseases) and the remaining 8 focused on cardiac disease, mainly heart failure. Validity, reliability, responsiveness, interpretability, and generalizability were assessed and the ISWT met acceptability levels in all domains. However, there remains no clear area where it is superior to the 6MWT, and because correlation with maximal oxygen consumption was only moderate, it is not a direct substitute for symptom-limited maximal cardiopulmonary exercise testing. The minimal clinically important difference was estimated at 48 m, a number strikingly similar to that for the 6MWT. In the final analysis, the ISWT is an available test, slightly more complex than the 6MWT but considerably less so than cardiopulmonary exercise testing. Its advantages over the 6MWT are hard to see, but it remains an option when clinical or research measurement of symptom-limited maximal exercise tolerance is needed.—SK

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Abdallah MS, Wang K, Magnuson EA, et al

JAMA. 2013;310(15);1581–1590.

Importance: The FREEDOM trial demonstrated that among patients with diabetes mellitus and multivessel coronary artery disease, coronary artery bypass graft (CABG) surgery resulted in lower rates of death and myocardial infarction but a higher risk of stroke when compared with percutaneous coronary intervention (PCI) using drug-eluting stents. Whether there are treatment differences in health status, as assessed from the patient's perspective, is unknown.

Objectives: To compare the relative effects of CABG vs PCI using drug-eluting stents on health status among patients with diabetes mellitus and multivessel coronary artery disease.

Design, Setting, and Participants: Between 2005 and 2010, 1900 patients from 18 countries with diabetes mellitus and multivessel coronary artery disease were randomized to undergo either CABG surgery (n = 947) or PCI (n = 953) as an initial treatment strategy. Of these, a total of 1880 patients had baseline health status assessed (935 CABG, 945 PCI) and comprised the primary analytic sample.

Interventions: Initial revascularization with CABG surgery or PCI.

Main Outcomes and Measures: Health status was assessed using the angina frequency, physical limitations, and quality-of-life domains of the Seattle Angina Questionnaire at baseline, at 1, 6, and 12 months, and annually thereafter. For each scale, scores range from 0 to 100 with higher scores representing better health. The effect of CABG surgery vs PCI was evaluated using longitudinal mixed-effect models.

Results: At baseline, mean (SD) scores for the angina frequency, physical limitations, and quality-of-life subscales of the Seattle Angina Questionnaire were 70.9 (25.1), 67.3 (24.4), and 47.8 (25.0) for the CABG group and 71.4 (24.7), 69.9 (23.2), and 49.2 (25.7) for the PCI group, respectively. At 2-year follow-up, mean (SD) scores were 96.0 (11.9), 87.8 (18.7), and 82.2 (18.9) after CABG and 94.7 (14.3), 86.0 (19.3), and 80.4 (19.6) after PCI, with significantly greater benefit of CABG on each domain (mean treatment benefit, 1.3 [95% CI, 0.3–2.2], 4.4 [95% CI, 2.7–6.1], and 2.2 [95% CI, 0.7–3.8] points, respectively; P < .01 for each comparison). Beyond 2 years, the 2 revascularization strategies provided generally similar patient-reported outcomes.

Conclusions and Relevance: For patients with diabetes and multivessel CAD, CABG surgery provided slightly better intermediate-term health status and quality of life than PCI using drug-eluting stents. The magnitude of benefit was small, without consistent differences beyond 2 years, in part due to the higher rate of repeat revascularization with PCI.

Editor's Comment: The debate on which revascularization procedure (coronary artery bypass graft [CABG] surgery or percutaneous coronary intervention [PCI]) is superior, particularly for certain subgroups, rages on in cardiology/cardiothoracic surgery. The FREEDOM Trial recently demonstrated that the benefits of CABG surgery were consistent across all major subgroup categories and that cost-effectiveness analysis demonstrated that CABG surgery was economically attractive as well. However, it was not clear whether CABG surgery should be recommended over PCI (particularly in the era of using drug-eluding stents) for patients with diabetes and multivessel coronary artery disease (CAD). While effectiveness and economics are certainly important factors, they do not consider patient perspective on these interventions. Consequently, this prospective health status and quality of life substudy was conducted alongside the FREEDOM Trial. The most important finding in this study was that although PCI resulted in more rapid improvement in health status and quality of life compared with CABG surgery, these benefits were transient and largely restricted to the first month of followup. Between 6 months and 2 years, health status and overall quality of life was better with CABG surgery versus PCI. Beyond 2 years, there were no consistent differences in any health status or quality of life measure between the 2 interventions. Seems as though this study supports the old adage “you can pay me now or you can pay me later” when it comes to weighing the impact these procedures will have on health status and quality of life.—PHB

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Lopez-Garcia E, Rodriguez-Artalejo F, Li TY, et al

Am J Clin Nutr. Published online first October 30, 2013, doi:10.3945/ajcn.113.068106.

Background: The role of the Mediterranean diet among individuals with previous cardiovascular disease (CVD) is uncertain.

Objective: The aim of this study was to assess the association between the Alternate Mediterranean Diet (aMED) score and all-cause, cardiovascular, and cancer mortality in men and women with CVD from the Health Professionals Follow-Up Study and the Nurses' Health Study.

Design: This study included 6137 men and 11,278 women with myocardial infarction, stroke, angina pectoris, coronary bypass, and coronary angioplasty. Diet was first assessed in 1986 for men and in 1980 for women with a food-frequency questionnaire (FFQ) and then repeatedly every 2–4 y. Cumulative consumption was calculated with all available FFQs from the diagnosis of CVD to the end of the follow-up in 2008.

Results: During a median follow-up of 7.7 y (IQR: 4.2–11.8) for men and 5.8 y (IQR: 3.8–8.0) for women, we documented 1982 deaths (1142 from CVD and 344 from cancer) among men and 1468 deaths (666 from CVD and 197 from cancer) among women. In multivariable Cox regression models, the pooled RR of all-cause mortality from a comparison of the top with the bottom quintiles of the aMED score was 0.81 (95% CI: 0.72, 0.91; P-trend < 0.001). The corresponding pooled RR for CVD mortality was 0.85 (95% CI: 0.67, 1.09; P-trend = 0.30), for cancer mortality was 0.85 (95% CI: 0.65, 1.11; P-trend = 0.10), and for other causes was 0.79 (95% CI: 0.65, 0.97; P-trend = 0.01). A 2-point increase in adherence to the aMED score was associated with a 7% (95% CI: 3%, 11%) reduction in the risk of total mortality.

Conclusion: Adherence to a Mediterranean-style diet pattern was associated with lower all-cause mortality in individuals with CVD.

Editor's Comment: Having lived and traveled extensively in Italy, I can personally attest to the nuances of the Mediterranean diet and overall healthy lifestyle in this part of the world. While dietary components will vary slightly from one Mediterranean region to the next, all share a high consumption of fruits and vegetables, a substantial intake of proteins from plant sources (legumes and nuts), and a high fat intake, mostly from monounsaturated fatty acids, mainly from olives and olive oil that is used abundantly. There is also a moderate to relatively high fish consumption and, in contrast, a low consumption of meat and meat products. Alcohol, usually in the form of red wine, is consumed in moderation and with meals (lunch and dinner). There is substantial evidence of the long-term benefits of the Mediterranean diet on health, but few studies have examined the effects of this diet among individuals with known cardiovascular disease. Thus, the purpose of the current study was to assess the long-term associations between a Mediterranean-style diet score and all-cause, cardiovascular, and cancer mortality during the 28-year followup in men and women with cardiovascular disease (CVD) from the Health Professionals and Nurses' Health studies. This study clearly found that there was an inverse association between Mediterranean diet score (higher score is more Mediterranean) and all-cause mortality in both men and women with a history of CVD. For each 2-point increase in diet score, there was a 7% reduction in all-cause mortality. The specific cause of the reduction in CVD (coronary artery disease vs cancer) was not determined definitively and the specific dietary mechanisms (monounsaturated fats, alcohol, omega-3 fatty acids, etc) responsible for these benefits could not be ascertained in these analyses. Despite these limitations, this study provides further compelling evidence that we should be recommending a Mediterranean-type diet to patients in our prevention/rehabilitation programs. While moving to Italy might be the most effective way to adopt this heart-healthy lifestyle, there are many simple day-to-day changes our patients can make to adopt these life-saving behaviors even without moving to the Mediterranean region. There are many good books/cookbooks available to help CVD patients change to this type of heart healthy diet. —PHB

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