PURPOSE Establishing accurate estimates of physical activity at baseline is essential for interventions assessing the potential benefits of exercise in adults with cancer. This study compares self-reported physical activity with independent data from activity trackers in women with early breast cancer (BC) recruited into a "walking" intervention during chemotherapy. METHODS Baseline (pre-intervention) questions inquired about self-reported physical activity-number of walking days/week and minutes/day-in women who were initiating chemotherapy for Stage I-III BC. Activity trackers measured steps per day during the first full week of chemotherapy. Weighted Kappa statistic and Pearson correlation coefficients were used to evaluate agreement and association between self-reported and objectively tracked physical activity levels, respectively. Univariate analyses were conducted to identify variables that may influence congruence between the two measures. RESULTS In a sample of 161 women, 77% were white, with mean age 56 years. Agreement between self-reported and objectively tracked physical activity was "fair" (kappa coefficient = 0.31), with most patients (59%) over-reporting their physical activity levels. There was weak correlation between the two measures (r = 0.24); however, correlation was strong in participants who were not married (r = 0.53) and/or living alone (r = 0.69). CONCLUSIONS Objective methods for assessing physical activity (activity trackers, accelerometers) should be used as a complement to self-reported measures to establish credible activity levels for intervention studies seeking to increase physical activity and/or measure the impact of increased physical activity in women with breast cancer.

中文翻译：

---

在乳腺癌中建立身体活动：自我报告与活动追踪器。

目的建立基线时身体活动的准确估计，对于评估癌症患者运动对身体的潜在益处的干预措施至关重要。这项研究将自我报告的体育活动与来自早期乳腺癌（BC）妇女在化学疗法期间被纳入“步行”干预措施的妇女的活动追踪器的独立数据进行比较。方法基线（干预前）询问有关自我报告的身体活动的信息，即正在开始BC期I-III化疗的女性的步行天数/周数和分钟数/天数。活动追踪器在化疗的第一个完整周内每天测量步骤。加权Kappa统计量和Pearson相关系数分别用于评估自我报告和客观跟踪的体育活动水平之间的一致性和关联性。进行了单变量分析，以识别可能影响这两个度量之间一致性的变量。结果在161名妇女的样本中，有77％是白人，平均年龄为56岁。自我报告和客观跟踪的身体活动之间的一致性是“公平的”（卡帕系数= 0.31），大多数患者（59％）过度报告了他们的身体活动水平。两种测量之间的相关性较弱（r = 0.24）；然而，未婚（r = 0.53）和/或独居（r = 0.69）的参与者之间的相关性很强。结论评估身体活动的客观方法（活动跟踪器，