Measurement of physical activity and sedentary behavior in breast cancer survivors
Background Breast cancer survivors’ self-perceived physical activity (PA) and sitting time (ST) may differ significantly from the general population and other survivor groups, so it is important that PA and ST measurement tools are compared within the breast cancer survivor population.
Objective To compare accelerometer and self-report estimates of PA and ST in breast cancer survivors.
Methods 414 breast cancer survivors (age, 56.8 years [SD, 9.2 years]; BMI, 26.2 kg/m2 [5.4 kg/m2]) wore an accelerometer for 7 consecutive days and completed a modified Godin Leisure-Time Exercise Questionnaire (GLTEQ), the International Physical Activity Questionnaire (IPAQ), and the Sitting Time Questionnaire (STQ) which all measured hours/minutes of activity/sitting per day. Mean differences and correlations of ST, light PA (LPA; ≤1.5 metabolic equivalents [METs]), and moderate and vigorous PA (MVPA; ≥3 METs) were compared using random-intercept mixed-effects regression models and the Spearman rank correlation coefficient (Spearman’s rho [rs], where rs = 1 means a perfect positive correlation, and rs = -1 means a perfect negative correlation).
Results Mean daily durations of MVPA were: accelerometer, 20.2 minutes; GLTEQ, 23.6 minutes (Pdiff = .02); and IPAQ, 87.4 minutes (Pdiff < .001). Correlations between accelerometer-estimated MVPA were moderate for the GLTEQ (rs = 0.56) and poor for the IPAQ (rs = 0.02). Mean daily durations of LPA were 239.5 minutes for the accelerometer and 15.4 minutes for the GLTEQ (Pdiff < .001); the measures were not correlated (rs = 0.004). Mean daily durations of ST were: accelerometer, 603.9 minutes; STQ, 611.8 minutes (Pdiff = 0.9); and IPAQ, 303.8 minutes (Pdiff < 0.001). Correlations with the accelerometer were fair (STQ: rs = 0.26; IPAQ: rs = 0.30). Differences in estimates varied by disease stage, age, presence of chronic conditions, and race.
Limitations Participants were predominantly white, highly educated, and high earners, which reduced generalizability.
Conclusions Congruency of measurement was dependent on tool, intensity of activity, and participant characteristics. Target outcome, implementation context, and population should be considered when choosing a measurement for physical activity or sitting time in breast cancer survivors.
Funding National Institute on Aging: #F31AG034025 (Dr Phillips), #AG020118 (Dr McAuley); National Cancer Institute: #K07CA196840 (Dr Phillips), #T32CA193193 (Dr Welch).†
Accepted for publication December 2, 2017
Correspondence whitney.welch@northwestern.edu
Disclosures The authors report no disclosures/conflicts of interest.
Citation JCSO 2018;16(1):e21-e29
†See Acknowledgment at end of article.
©2018 Frontline Medical Communications
doi https://doi.org/10.12788/jcso.0387
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Limitations
There were a few limitations within the current study that should be taken into account. First, the accelerometer cut-points used were developed with healthy, young adults; therefore using different cut-points may have yielded different results.34 Given the large age range in our participants (23-84 years), we believe the use of these cut-points was justified, in lieu of population-specific (ie, older adults) cut-points. In addition, limitations to estimating activity from an accelerometer include the inability to capture certain activities such as swimming and cycling and the aforementioned inability to distinguish between body postures (ie, sitting vs standing).41 The participants were predominantly white, highly educated, and high earners (85.2% earned ≥$40,000 per year), therefore, the present results may not be generalizable to survivors from more diverse backgrounds. However, as far as we know, this is the first study to report the congruency of estimated ST, LPA, and MVPA across multiple measurement tools in a nationwide sample of breast cancer survivors who were heterogeneous in terms of disease characteristics (ie, stage, treatment, time since diagnosis).
Conclusions
Our findings suggest that physical activity and ST estimates in breast cancer survivors may be dependent on the measurement tool used. In addition, congruency of measurement tools was dependent on activity intensity of interest, and participant age, race, and disease history may also influence these factors. Therefore, researchers should consider the intended outcomes of interest, the context in which the tool is being used (ie, clinical versus research), the available resources, and the participant population before they select a measurement tool for estimating physical activity and sitting time in breast cancer survivors.
Acknowledgment
This work was supported by grant #F31AG034025 from the National Institute on Aging (Dr Phillips); Shahid and Ann Carlson Khan endowed professorship and grant #AG020118 from the National Institute on Aging (Dr McAuley). Dr Phillips is supported by the National Cancer Institute #K07CA196840, and Dr Welch is supported by National Institute of Health/National Cancer Institute training grant CA193193. All data for this study were collected at the University of Illinois Urbana Champaign.
