Soyang Kwon: Buehler Center for Health Policy and Economics, Feinberg School of Medicine, Northwestern University, 750 N Lakeshore Drive, Chicago, IL, 60611, USA. soyang.kwon@northwestern.edu. ORCID
Bridget Armstrong: Department of Exercise Science, Arnold School of Public Health, University of South Carolina, Columbia, South Carolina, USA.
Nina Wetoska: Buehler Center for Health Policy and Economics, Feinberg School of Medicine, Northwestern University, 750 N Lakeshore Drive, Chicago, IL, 60611, USA.
Selin Capan: Buehler Center for Health Policy and Economics, Feinberg School of Medicine, Northwestern University, 750 N Lakeshore Drive, Chicago, IL, 60611, USA.
BACKGROUND: The PROMIS Early Childhood Physical Activity (PROMIS EC PA) scale is a recently developed PROMIS Early Childhood measure to assess PA among children aged 1-5 years. The purpose of this study was to examine test-retest reliability and convergent validity of the PROMIS EC PA scale among toddlers. METHOD: An ancillary study was conducted in the toddler-mother dyad sample of the Child and Mother Physical Activity Study. Mothers completed the 7-item PROMIS EC PA scale twice: during a study visit (test) and on the last day when their Child's wore an ActiGraph accelerometer on the hip for 7 days (retest). The PROMIS EC PA summed score was calculated by totaling scores from items 1-5. Test-retest reliability was assessed using intraclass correlation coefficient (ICC) for test and retest PROMIS EC PA. Convergent validity was assessed using rank correlation coefficients (rho) between PROMIS EC PA scores and accelerometer-measured moderate- and vigorous-intensity PA (MVPA). RESULTS: Among 74 participants (56% female; 19��������4 months of mean age with range of 12-30 months), average accelerometer-measured MVPA was 76��������24 min/day. The median number of days between PROMIS EC PA test and retest was 8 days (IQR���=���6 to 8), with an average PROMIS EC PA summed score of 11.0��������3.5 at test and 10.5��������3.4 at retest. ICC for the test-retest PROMIS EC PA summed scores was 0.72 (95% CI���=���0.59-0.82). The rank correlation between the PROMIS EC PA summed score and accelerometer-measured MVPA was 0.13 (95% CI=-0.10 to 0.35; p���=���0.28). CONCLUSION: In a sample of children aged 12-30 months, test-retest reliability for the PROMIS EC PA scale was moderate and its convergent validity against accelerometer-measured MVPA was poor. Prior to a widespread use of the PROMIS EC PA scale in large-scale research and clinical practice, the tool should be further refined and validated to elucidate how young children's lived PA experience as measured in the PROMIS EC PA scale is relevant to their health and wellbeing outcomes.
