Resumo

Background: A shift towards the use of wrist-worn instead of hip-attached accelerometers has increased compliance to accelerometer wear-time criteria applied to estimate 24- hour movement behaviors. However, researchers still face challenges on how to overcome potential selection bias due to non-adherence to accelerometer protocols.
Purpose: This study aimed to evaluate the impact of two wrist-worn accelerometer protocols on accelerometer wear time; and to analyse sociodemographic and behavioral correlates of protocol compliance.

Methods: The sample comprised 143 high school students from a school in Florianópolis, Brazil. Participants wore GT3x+ and wGT3x Actigraph accelerometers attached to the non-dominant wrist by a disposable PVC or a reusable fabric wristband for 24 hours over seven days. Those who wore the reusable fabric band, but not their counterparts, were instructed to remove the device on water-based activities. Participants answered to a questionnaire about sociodemographic and behavioral characteristics, and reported their experience on wearing the accelerometer. We computed the non-wear time based on accelerometer raw data and checked participants\\\' compliance with eligibility criteria (i.e., at least three valid weekdays and one weekend days computed for valid day definitions of 16 and 23 hours). Kolmogorov-Smirnov test was used to compare the cumulative distribution function of accelerometer wear time between protocols. Logistic regression models were applied to evaluate correlates of protocol compliance.

Results: The expected sample loss due to the increase of wear time criteria is presented in Figure 1. Participants who wore a disposable band had greater compliance compared to those who wore a reusable band for both 16- (93% versus 76%, respectively) and 23-hour valid day definitions (91% versus 50%, respectively). Participants who worked (OR: 0.17; 95%CI 0.04-0.73), who reported that wearing the accelerometer hindered their daily activities (OR: 0.62; 95%CI 0.38-0.99), and those who reported feeling ashamed when wearing the accelerometer were less likely to comply with accelerometer protocols (OR: 0.59; 95%CI 0.36-0.96).

Conclusions: The use of disposable wristbands improved compliance with 24-hour accelerometer protocols compared to reusable bands. However, the feeling of shame due to wearing the accelerometer and the effect of the device on hindering daily activities may be a barrier to participants' adherence to rigorous protocols

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