Validation and feasibility of a caloric expenditure measuring device in women with early-stage breast cancer.

PURPOSE: The purpose of this study is to validate the Bodybugg (BB), a caloric expenditure measuring device, in breast cancer patients undergoing adjuvant and neoadjuvant chemotherapy for early-stage breast cancer. METHODS: Twenty-five women with stages I-III breast cancer who were to receive adjuvant dose-dense doxorubicin/cyclophosphamide were recruited. Participants were asked to wear the BB and record activity logs for seven pretreatment days (prior to commencing chemotherapy) and seven posttreatment days (upon completing cycle 4 of chemotherapy). The BB's caloric expenditure measurements were used to calculate metabolic equivalent (MET) values of patients' recorded activities. BB-calculated METs were compared with matching METs from the 2011 Compendium of Physical Activities Tracking Guide to assess accuracy of the device. RESULTS: The overall patient sample wore the device for an average of 5.32 (SD 1.75) pre- and 4.88 (SD 2.01) posttreatment days. The mean pairwise difference between BB and Compendium METs was 0.043 (SD 0.77) for 308 pretreatment activities recorded by 12 patients and 0.065 (SD 0.61) for 108 posttreatment activities recorded by 6 patients, indicating close to zero bias between the BB's and Compendium's measurements. Hierarchical linear modeling showed that Compendium METs strongly predict for BB METs (P < 0.00001). CONCLUSIONS: The BB is feasible to use in study designs involving defined time periods of measurement and provides accurate and objective measurements of caloric expenditure in breast cancer patients.

6-minute walk work for assessment of functional capacity in patients with COPD.

UNLABELLED: The 6-min walk (6MW) test is commonly used to assess exercise capacity in patients with COPD and to track functional change resulting from disease progression or therapeutic intervention. Not surprisingly, distance covered has been the preferred outcome for this test. However, distance walked does not account for differences in body weight that are known to influence exercise capacity. OBJECTIVE: The aim of this study was to evaluate the 6-min distance x body weight product (6MWORK) as an improved outcome measure with a solid physiologic foundation. PATIENTS AND METHODS: One hundred twenty-four men and women with moderate-to-severe COPD volunteered and completed the testing sequence, which included pulmonary function, a peak effort ramp cardiopulmonary exercise study with gas exchange, and the 6MW. Means and SD were generated for the variables of interest. Differences were analyzed using analysis of variance techniques. Correlation coefficients and receiver operating characteristic (ROC) curves were calculated for the 6-min walk distance (6MWD) and 6MWORK with indexes of pulmonary function, work performance, and Borg scores for dyspnea and effort. RESULTS: Men and women presented with a significant smoking history that also differed by gender (48 vs 66 pack-years, respectively; p < 0.01). The mean (+/- SD) FEV(1) values were 45 +/- 12.6% and 48 +/- 12.1%, respectively (not significant), while the diffusing capacity of the lung for carbon monoxide (DLCO) was 14.7 +/- 6.1 vs 10.3 +/- 3.9 mL/min/mm Hg, respectively (p < 0.001), for men and women. The 6MWD averaged 416.8 +/- 79.0 m for men and 367.8 +/- 78.6 m for women, and these differences were significant (p < 0.002). When 6MWD was compared as the percent predicted of normal values, each gender presented with a similar reduction of 78.6 +/- 14.5% vs 79.9 +/- 17.5% (p > 0.05), respectively. 6MWORK averaged 35,370 +/- 9,482 kg/m and 25,643 +/- 9,080 kg/m (p < 0.0001) for men and women, respectively. 6MWORK yielded higher correlation coefficients than did 6MWD when correlated with DLCO, lung diffusion for alveolar ventilation, FEV(1), FEV(1)/FVC ratio, watts, peak oxygen uptake, peak minute ventilation, and peak tidal volume. The ROC curve demonstrated that 6MWORK had a significantly larger calculated area under the curve (p < 0.05) [plot of 100-sensitivity to specificity for each variable of interest for all subjects] than 6MWD when differentiating an objectively selected definition of low work capacity vs high work capacity (bike ergometry work, < 55 vs > 55 W, respectively). CONCLUSIONS: We conclude that work calculated as the product of distance x body weight is an improved outcome measure for the 6MW. 6MWORK can be used whenever the 6MW is required to estimate a patient's functional capacity. This measure is also a common measure, which can be converted to indexes of caloric expenditure for direct cross-modality comparisons.

Criterion validity of the Duke Activity Status Index for assessing functional capacity in patients with chronic obstructive pulmonary disease.

PURPOSE: This study evaluated the concurrent criterion validity of the Duke Activity Status Index (DASI) with respect to standard physiologic work capacity indices in patients with chronic obstructive pulmonary disease (COPD) and compared its performance with similar surrogates. METHODS: 119 patients with moderate to severe COPD (86 men, 33 women) completed medical and smoking histories, physical examination, pulmonary function testing (PFT), cycle ergometry (CE), arm ergometry (AE), and 6-minute walk distance (6MWD), DASI, the Sickness Impact Profile-68 (SIP-68) and the Chronic Respiratory Disease Questionnaire (CRDQ). Correlation methods were used to assess the validity of the potential surrogates DASI and the domain scores for SIP-68 and CRDQ, with the standards CE, AE, PFT, and 6MWD (as a standard). RESULTS: The mean DASI score was 33.4 +/- 13.0. Significant Pearson correlations (P <.01) were observed between the DASI and PFT outcomes maximum voluntary ventilation (r =.28); peak expiratory flow (r =.21); diffusion capacity of lung for carbon monoxide (r =.30). For CE, the correlations with DASI were oxygen consumption (VO(2))(r =.34); minute ventilation (r =.25); watts (r =.37). For AE, the correlations with DASI were VO(2) (r=.38); watts (r =.47). For 6MWD, the correlation was r =.53. Higher correlations were obtained for the distance completed during the first minute of the 6MWD and ergometric indices as well as DASI scores: watts(AE) (r =.39); VO(2AE) (r =.45); watts(CE) (r =.50); VO(2CE) (r =.44). Correlation coefficients for all SIP-68 and CRDQ domain and total scores were lower than corresponding correlations obtained for the DASI. Regression analysis demonstrated that the DASI and 6MWD were important (P <.05) for predicting VO(2) or work for CE while DASI and SIP range or CRDQ dyspnea entered for AE, when gender, age, BMI, and the FEV1 were forced into the model. In forward stepwise analyses, DASI entered first for AE, and 6MWD entered first for CE. The DASI was selected in 3 of 4 models with R(2) values ranging from.47 to.70. SIP-68 and CRDQ subscores were significant as additional predictors. CONCLUSIONS: DASI has high criterion validity for predicting CE and/or AE outcomes in the COPD population. It is warranted in addition to the 6MWD, and its predictive significance and simplicity recommends it over several other self-administered instruments for evaluating functional capacity.