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Convergent validity of four accelerometer cutpoints with direct observation of preschool children's outdoor physical
David Kahan1, Virginie Nicaise, Karen Reuben
1School of Exercise & Nutritional Sciences, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-7251, USA. dkahan@mail.sdsu.edu
Insights
Validating accelerometer cutpoints is crucial for accurately measuring physical activity in preschool children. Specific cutpoints showed better agreement with the OSRAC-P for sedentary behavior and moderate-to-vigorous physical activity.
Area of Science:
- Pediatric physical activity assessment
- Measurement validity in child research
Background:
- Childhood obesity is a significant public health concern, with over one-fifth of American preschoolers classified as overweight or obese.
- Increasing physical activity is a key strategy to combat childhood overweight and obesity.
- Accelerometers are commonly used to measure physical activity in children, but varying cutpoint interpretations lead to inconsistent results.
Purpose of the Study:
- To evaluate the convergent validity of four ActiGraph accelerometer cutpoints against the Observation System for Recording Activity in Children-Preschool (OSRAC-P).
- To determine the most accurate cutpoints for assessing sedentary behavior (SED) and moderate-to-vigorous physical activity (MVPA) in preschool-aged children.
Main Methods:
- Two studies involved 69 preschool children (4-5 years old) during unstructured outdoor play.
- Study 1 compared aggregate SED and MVPA percentages using two-proportion z-tests and Bland Altman plots (N=57).
- Study 2 analyzed time-matched 5-s intervals using percent agreement, kappa, and classification functions (N=12).
Main Results:
- In Study 1, Sirard, Trost, Pfeiffer, Dowda, and Pate (2005) cutpoints demonstrated the best convergence with OSRAC-P for SED and MVPA.
- Study 2 indicated that Sirard et al. cutpoints were more sensitive for SED, while Pate, Almeida, McIver, Pfeiffer, and Dowda (2006) cutpoints were more sensitive for MVPA.
Conclusions:
- The selection of accelerometer cutpoints for preschool children should consider the specific physical activity of interest.
- Epoch/observation interval duration and the desired stringency for classifying activity levels are critical factors in cutpoint choice.
Purpose:
More than one fifth of American preschool-aged children are classified as overweight/obese. Increasing physical activity is one means of slowing/reversing progression to overweight or obesity. Measurement of physical activity in this age group relies heavily on motion sensors such as accelerometers. Output is typically interpreted through application of one of several cutpoints to quantify the amount of time spent at various physical activity levels. Cutpoint nonequivalence has resulted in widely varying estimates of physical activity. Thus, we sought to ascertain the convergent validity of four ActiGraph accelerometer cutpoints with the Observation System for Recording Activity in Children-Preschool (OSRAC-P).
Method:
Two studies were conducted with sixty-nine 4- and 5-year-olds during unstructured outdoor free play at a single university campus preschool in Southern California. In Study 1 (N = 57), percentages of time spent in sedentary behavior (SED) and moderate-to-vigorous physical activity (MVPA) were compared at the aggregate level using the two-proportion z-test and Bland Altman plots. In Study 2 (N = 12), time-matched 5-s intervals between accelerometery and the OSRAC-P were compared using percent agreement, kappa, and classification functions.
Results:
In Study 1, cutpoints by Sirard, Trost, Pfeiffer, Dowda, and Pate (2005) best converged with the OSRAC-P estimates of SED and MVPA. In Study 2, Sirard et al. cutpoints and those by Pate, Almeida, McIver, Pfeiffer, and Dowda (2006) were more sensitive in detecting SED and MVPA, respectively.
Conclusions:
Choosing a cutpoint in this age group should be based on the exposure of interest, epoch/observation interval duration, and required degree of stringency for classifying physical activity level.
