Ferrari Pietro, Friedenreich Christine, Matthews Charles E
Nutrition and Hormones Group, International Agency for Research on Cancer, Lyon, France.
Am J Epidemiol. 2007 Oct 1;166(7):832-40. doi: 10.1093/aje/kwm148. Epub 2007 Aug 1.
Epidemiologic studies have demonstrated that physical inactivity is an important determinant of numerous chronic diseases. However, self-reported estimates of physical activity contain measurement errors responsible for attenuating relative risk estimates. A validation study conducted in 2002-2003 at the Alberta Cancer Board (Canada) included a physical activity questionnaire, four 7-day physical activity logs, and four sets of accelerometer data from 154 study subjects (51% women) aged 35-65 years. The authors used a measurement error model to evaluate validity of the different types of physical activity assessment, and the attenuation factors, after taking into account error correlations between self-reported measurements. The validity coefficients, which express the correlation between measured and true exposure, were higher for accelerometers (0.81, 95% confidence interval (CI): 0.76, 0.85) compared with the physical activity log (0.57, 95% CI: 0.47, 0.66) and questionnaire measurements (0.26, 95% CI: 0.12, 0.40). The estimate of the attenuation factor for questionnaires was 0.13 (95% CI: 0.05, 0.23). Accuracy of physical activity questionnaire measurements was higher for men than for women, for younger individuals, and for those with a lower body mass index. Because the degree of attenuation in relative risk estimates is substantial, after the role of error correlations was considered, validation studies quantifying the impact of measurement errors on physical activity estimates are essential to evaluate the impact of physical inactivity on health.
流行病学研究表明，缺乏身体活动是众多慢性疾病的一个重要决定因素。然而，自我报告的身体活动估计值存在测量误差，这会削弱相对风险估计值。2002年至2003年在加拿大艾伯塔癌症委员会进行的一项验证研究，纳入了一份身体活动问卷、四份7天的身体活动日志，以及来自154名年龄在35至65岁之间的研究对象（51%为女性）的四组加速度计数据。作者使用测量误差模型来评估不同类型身体活动评估的有效性以及衰减因子，同时考虑了自我报告测量之间的误差相关性。表示测量暴露与真实暴露之间相关性的有效性系数，加速度计更高（0.81，95%置信区间（CI）：0.76，0.85），相比之下身体活动日志为（0.57，95%CI：0.47，0.66），问卷测量为（0.26，95%CI：0.12，0.40）。问卷的衰减因子估计值为0.13（95%CI：0.05，0.23）。身体活动问卷测量的准确性，男性高于女性，年轻人高于年长者，体重指数较低者高于体重指数较高者。由于在考虑误差相关性的作用后，相对风险估计值的衰减程度相当大，因此量化测量误差对身体活动估计值影响的验证研究，对于评估缺乏身体活动对健康的影响至关重要。
