Agreement of different reference equations to classify patients with COPD as having reduced or preserved 6MWD.

BACKGROUND: Interpretation of the six-minute walk distance (6MWD) is enhanced by using recommended reference equations. Whenever possible, the choice of equation should be region-specific. A potential problem is that different equations for the 6MWD may have been developed for the same population, and it may be complicated to choose the most suitable. OBJECTIVE: To verify the agreement of different reference equations in classifying patients with Chronic Obstructive Pulmonary Disease (COPD) as having reduced or preserved 6MWD. METHODS: 159 patients with COPD performed the six-minute walk test according to international standardization. They were classified as having reduced 6MWD if it was below the lower limit of normal. Five Brazilian equations (Iwama; Britto1; Britto2; Dourado; Soares) and the two non-Brazilian equations most cited worldwide (Troosters; Enright) were used. The agreement for patients classified as reduced or preserved 6MWD was verified by Cohen's Kappa (pair-to-pair) analysis. The proportion of patients classified as having reduced walked distance was compared by the Chi-squared test. RESULTS: Agreement between equations varied largely in classifying subjects as having reduced or preserved 6MWD (Kappa: 0.10-0.82). Brazilian equations with the highest agreement were Iwama, Britto1 and Britto2 (Kappa>0.75). The proportion of patients classified as having reduced 6MWD was statistically similar only between equations in which the agreement was higher than 0.70. CONCLUSION: Even reference equations from the same country vary considerably in the classification of reduced or preserved 6MWD, and it is recommended that the region-specific ones be used as they give with higher agreement for similar and comparable interpretation of the patients' functional exercise capacity.

Fat-free mass depletion in patients with COPD in Brazil: development of a new cutoff point and its relation with mortality and extrapulmonary manifestations.

BACKGROUND/OBJECTIVES: None of the cutoff points for fat-free mass index (FFMI) were tested for the Brazilian population, and it is unknown whether the available ones are able to discriminate extrapulmonary disease manifestations. This cross-sectional study aims to develop and validate a cutoff point for FFM depletion based on Brazilian patients with chronic obstructive pulmonary disease (COPD) and to verify its association and of previously published cutoffs with extrapulmonary manifestations. SUBJECTS/METHODS: A new cutoff point was obtained from the best FFMI value for discrimination of preserved exercise capacity in a sample of patients (n=57). The discriminative capacity was assessed in another sample (n=96). The new cutoff point and other previously published ones were tested to discriminate low exercise capacity, physical inactivity, sedentary lifestyle and low quality of life. A receiver operation characteristics curve with area under the curve (AUC) value was plotted and each cutoff points' discriminative capacity was calculated. Cox regression and Kaplan-Meier method assessed the association between the cutoff points and mortality. RESULTS: The new cutoff points for FFMI were 14.65 kg/m2 for women (AUC=0.744; sensitivity (Se)=0.88; specificity (Sp)=0.60) and 20.35 kg/m2 for men (AUC=0.565; Se=0.36; Sp=0.81). The new cutoffs were the best to discriminate poor exercise capacity assessed by walked distance in % predicted and quality of life. Only the new cutoff point was associated with mortality (HR=2.123; 95% CI: 1.03-4.33, P=0.039, log rank P=0.035). CONCLUSIONS: Only the new cutoff point was associated with all-cause mortality, and it had the highest discriminating capacity for exercise capacity and quality of life in Brazilian patients with COPD.

Physiotherapy and rehabilitative interventions in patients with chronic respiratory diseases: exercise and non-exercise treatment.

AIM: The aim of this literature review was to describe and discuss the available evidence about different modalities of physical therapy treatment and pulmonary rehabilitation (PR) involving exercise training in patients with chronic obstructive pulmonary disease (COPD), asthma, bronchiectasis and interstitial lung disease (ILD). METHODS: The search was performed by using the Cochrane Library and PubMed databases. We selected studies published between 2001 and 2012 which involved physiotherapy treatment and included patients with COPD, asthma, bronchiectasis or ILD, aged 18 years or more, in stable or unstable disease condition. RESULTS AND CONCLUSION: PR involving exercise training was effective in improving exercise capacity, muscle force, quality of life and reducing symptoms in patients with COPD and asthma. Although there are few studies published about exercise training in patients with bronchiectasis, improvement in exercise capacity and quality of life in those patients was also observed. Patients with ILD also respond to exercise training; however, the response is less pronounced than in COPD and they lose the gains more quickly. Non-exercise-based interventions, such as bronchial hygiene techniques and inspiratory muscle training, also present positive results when applied to patients with COPD, asthma and bronchiectasis. In some cases it is recommended that these interventions are combined with exercise training. Studies about non-exercise based interventions applied to patients with ILD are still necessary.

Reproducibility of 6-minute walking test in patients with COPD.

The reproducibility of the 6-min walking test (6MWT) needs to be more solidly studied. This study aimed to investigate the reproducibility of two 6MWTs performed on subsequent days in a large and representative sample of patients with chronic obstructive pulmonary disease (COPD), and to quantify the learning effect between the two tests, as well as its determinants. In a retrospective observational study, 1,514 patients with COPD performed two 6MWTs on subsequent days. Other measurements included body composition (dual X-ray absorptiometry), dyspnoea (Medical Research Council scale) and comorbidity (Charlson index). Although the 6MWT was reproducible (intraclass correlation coefficient = 0.93), patients walked farther in the second test (391 m, 95% CI 155-585 m versus 418 m, 95% CI 185-605 m; p<0.0001). On average, the second 6MWT increased by 27 m (or 7%), and 82% of patients improved in the second test. Determinants of improvement ≥ 42 m in the second test (upper limit of the clinically important change) were as follows: first 6MWT <350 m, Charlson index <2 and body mass index <30 kg · m(-2) (OR 2.49, 0.76 and 0.60, respectively). The 6MWT was statistically reproducible in a representative sample of patients with COPD. However, the vast majority of patients improved significantly in the second test by an average learning effect of 27 m.