Six-minute walking distance in women with COPD.

BACKGROUND: The 6-minute walk distance (6MWD) has been useful in the evaluation of men with COPD. Little is known about 6MWD in women with the disease. OBJECTIVES: Using healthy women as a reference, to evaluate the factors that help determine 6MWD in women with COPD. To explore if the 350 meters threshold differentiates survival in women as it does in men. METHODS: Healthy women (n = 164) and with COPD (n = 223) were included in the study. Age, pack-years history, smoking status, comorbidities (Charlson Index), BMI, MRC dyspnea, spirometry and 6MWD were recorded in all participants and PaO(2) and IC/TLC in COPD women. The patients were prospectively followed and deaths registered. Factors predicting 6MWD were determined by multiple regression analysis. ROC analysis was used to calculate the best threshold value for the 6MWD with mortality as gold standard. Kaplan-Meier curves compared survival of patients that walked more or less than 350 m by age categories. RESULTS: The 6MWD is decreased in women with COPD. Values decrease with age and GOLD stages. Age, BMI, smoking status, comorbidities, MRC and FEV(1%) are statistical significant predictors of 6MWD. A 350 m cut-off value has a good sensitivity and specificity to predict (73% and 80% respectively) and differentiate survival (p < 0.001 for log rank comparisons) in these patients. CONCLUSIONS: In women with COPD, the 6MWD decreases with age and GOLD stages. A 350 m distance is a valid threshold to differentiate survival. Further studies in different settings should confirm our findings.

Prognostic assessment in COPD: health related quality of life and the BODE index.

RATIONALE: COPD is a debilitating disease with increasing mortality worldwide. The BODE index evaluates disease severity and the St George's Respiratory Questionnaire (SGRQ) measures health status. OBJECTIVE: To identify the relationship between BODE index and the SGRQ and to test the predictive value of both tools against survival. METHODS: Open cohort study of 1398 COPD patients (85% male) followed for up to 10 years. MEASUREMENTS AND MAIN RESULTS: At the time of the inclusion, clinical data, forced spirometry and 6 min walking distance were determined and BODE index and SGRQ were calculated. Vital status and cause of death were documented at the end of follow-up. RESULTS: The cohort's mean of FEV1% predicted was 46 ± 18%, BODE index was 3.6 ± 2.5, and SGRQ% total score was 49 ± 20. The SGRQ scores increased progressively as severity of COPD increased by BODE quartiles. The correlation between SGRQ and BODE index was good (r = 0.58, p < 0.0001). Both tests correlated with COPD survival (BODE = -0.4 vs. SGRQ = -0.20, p < 0.0001). The area under the curve (AUC) for the BODE index was 0.77 vs. 0.66 for the SGRQ % total score (p < 0.001). CONCLUSIONS: Health status as measured by SGRQ worsens with disease severity evaluated by the BODE index. Both tools predict mortality and provide complimentary information in the evaluation of patients with COPD.

Predictors of Survival in COPD: more than just the FEV1.

Chronic obstructive pulmonary disease (COPD) ranks fourth as a cause of death in the United States, behind heart disease, cancer, and stroke. Additionally, since serious co-morbidities are often present in patients with COPD, many die from other diseases such as cardiac disease or cancer. Not surprisingly, multiple factors, reflective of both respiratory disease process and the substantial co-morbidity, predict survival in the disease. As might be expected, physiologic derangements such as airflow obstruction, hypoxemia, lung hyperinflation, and exercise capacity predict survival in COPD. Anemia, cachexia and reductions in lean body mass also relate to prognosis. Perhaps less recognized is the more recent documentation that more subjective assessments, such as dyspnea and health related quality of life, are also important predictors of survival. The integration of some of the most important of these variables may provide a more comprehensive evaluation of disease severity. For example, a validated multi-dimensional disease rating that includes the body mass index (B), degree of airflow obstruction (O), dyspnea (D), and exercise capacity (E) (BODE Index) is capable of predicting COPD-related hospitalization and mortality more than its individual components.

The 6-min walk distance, peak oxygen uptake, and mortality in COPD.

In patients with COPD, the maximal oxygen uptake (Vo2) measured at peak exercise and the 6-min walk distance (6MWD) have been associated with survival; however, no study has compared the strength of the association in the same patients. In this study, we compared the association between the 6MWD and peak Vo2 and mortality in 365 patients with COPD. Patients' cardiopulmonary cycle ergometry test results and 6MWD were determined at entry, and patients were followed up for a mean period of 67 months. There were 171 deaths. Compared with survivors, nonsurvivors were older (mean [+/- SD] age, 67.9 +/- 8 vs 65.9 +/- 8 years, respectively; p = 0.008), had worse mean FEV1 (36.5 +/- 12 vs 42.6 +/- 14 L, respectively; p = 0.02), had lower mean peak Vo2 (9.8 +/- 3 vs 11.8 +/- 3.6 mL/Kg/min, respectively; p < 0.0001), lower mean 6MWD (312 +/- 104 vs 377 +/- 95 m, respectively; p < 0.0001), and lower mean exercise minute ventilation (37.4 +/- 12 vs 42.3 +/- 13 L/min, respectively; p = 0.004). Univariate analysis showed that peak Vo2 and 6MWD as well as comorbidity, FEV1, and body mass index were associated with death. Logistic regression analysis with mortality as the dependent variable revealed that 6MWD (hazard ratio [HR], 0.996; 95% confidence interval [CI], 0.993 to 0.999; p < 0.01) had a stronger association than the peak Vo2 (HR, 0.971; 95% CI, 0.959 to 1.000; p = 0.050) with mortality. This study shows the 6MWD is as good predictor of mortality as the peak Vo2 in patients with COPD.

Predictors of mortality in chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) has become a major and growing health problem, with a mortality rate that continues to increase. Several factors, have been identified as individual predictors of mortality in COPD. This article reviews individual predictors for mortality. It also discusses the ability of an integrated, multidimensional tool to more broadly characterize COPD severity, assess response to therapeutic interventions and exacerbations, and predict mortality.

Impact of COPD exacerbations on patient-centered outcomes.

BACKGROUND: Frequent exacerbations are associated with a faster decline in FEV(1), impaired health status, and worse survival. Their impact and temporal relationship with other outcomes such as functional status, dyspnea, and the multidimensional body mass index, obstruction, dyspnea, exercise capacity (BODE) index remain unknown. HYPOTHESIS: We reasoned that exacerbations affect the BODE index and its components, and that changes in the BODE index could be used to monitor the effect of exacerbations on the host. STUDY DESIGN: Prospective observational study in a Veterans Affairs medical center. METHODS: We studied 205 patients with COPD (mean [+/- SD] FEV(1), 43 +/- 15% predicted), and recorded the body mass index, FEV(1) percent predicted, modified Medical Research Council dyspnea scale, 6-min walk distance, and the BODE index at baseline, during the exacerbation, and at 6, 12, and 24 months following the first episode, and documented all exacerbations for 2 years after the first acute exacerbation. RESULTS: From the cohort, 130 patients (63%) experienced 352 exacerbations or (0.85 exacerbations per patient per year); 48 patients (23%), experienced one episode, 82 patients (40%) experienced 2 or more exacerbations, and 50 patients required hospitalization. At study entry, exacerbators had a worse mean baseline BODE index score (4.2 +/- 2.1 vs 3.57 +/- 2.3, respectively; p < 0.03). The BODE index score worsened by 1.38 points during the exacerbation, and remained 0.8 and 1.1 points above baseline at 1 and 2 years, respectively. There was little change in BODE index score at 2 years in nonexacerbators. CONCLUSION: COPD exacerbations negatively impact on the BODE index and its components. The BODE index is a sensitive tool used to assess the impact of exacerbations and to monitor COPD disease progression.

Surrogates of mortality in chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) remains a leading cause of disability and death in the United States. The identification and amelioration of systemic manifestations of COPD may improve long-term outcomes, including survival. These systemic manifestations often correlate with increased risk of mortality and may be considered surrogates of disease severity. Several potential clinical surrogates are evaluated, including airflow obstruction, dyspnea, malnutrition, hypoxemia, exercise capacity, lung hyperinflation, and anemia. The evidence in support of the impact of various COPD treatment modalities on systemic manifestations of COPD is also reviewed. Finally, the usefulness of measuring body mass index, degree of airflow obstruction, dyspnea, and exercise capacity in combination (the BODE index), as a measure of disease severity and mortality risk in COPD, is examined and found to be a simple-to-use tool for predicting COPD-related hospitalization and mortality.

New treatment strategies for COPD. Pairing the new with the tried and true.

Knowledge about COPD has increased substantially in recent years. Smoking cessation campaigns have significantly decreased smoking prevalence in the United States, and similar efforts in the rest of the world will likely have the same impact. The consequence should be a drop in incidence of COPD in the years to come. The use of LTOT for hypoxemic patients has resulted in increased survival, and expanded drug therapy options have effectively improved dyspnea and quality of life. Recent studies have documented the benefits of pulmonary rehabilitation. In addition, noninvasive mechanical ventilation offers new alternatives for patients with acute or chronic failure. Furthermore, the revival of surgery for emphysema may serve as an alternative to lung transplantation for patients with severe COPD who remain symptomatic despite maximal medical therapy. With all of these options, a nihilistic attitude toward management of COPD is not justified.

The body-mass index, airflow obstruction, dyspnea, and exercise capacity index in chronic obstructive pulmonary disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is characterized by an incompletely reversible limitation in airflow. A physiological variable--the forced expiratory volume in one second (FEV1)--is often used to grade the severity of COPD. However, patients with COPD have systemic manifestations that are not reflected by the FEV1. We hypothesized that a multidimensional grading system that assessed the respiratory and systemic expressions of COPD would better categorize and predict outcome in these patients. METHODS: We first evaluated 207 patients and found that four factors predicted the risk of death in this cohort: the body-mass index (B), the degree of airflow obstruction (O) and dyspnea (D), and exercise capacity (E), measured by the six-minute-walk test. We used these variables to construct the BODE index, a multidimensional 10-point scale in which higher scores indicate a higher risk of death. We then prospectively validated the index in a cohort of 625 patients, with death from any cause and from respiratory causes as the outcome variables. RESULTS: There were 25 deaths among the first 207 patients and 162 deaths (26 percent) in the validation cohort. Sixty-one percent of the deaths in the validation cohort were due to respiratory insufficiency, 14 percent to myocardial infarction, 12 percent to lung cancer, and 13 percent to other causes. Patients with higher BODE scores were at higher risk for death; the hazard ratio for death from any cause per one-point increase in the BODE score was 1.34 (95 percent confidence interval, 1.26 to 1.42; P<0.001), and the hazard ratio for death from respiratory causes was 1.62 (95 percent confidence interval, 1.48 to 1.77; P<0.001). The C statistic for the ability of the BODE index to predict the risk of death was larger than that for the FEV1 (0.74 vs. 0.65). CONCLUSIONS: The BODE index, a simple multidimensional grading system, is better than the FEV1 at predicting the risk of death from any cause and from respiratory causes among patients with COPD.