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.