Reliably measuring ambulatory activity levels of children and adolescents with cerebral palsy.
OBJECTIVE
To identify sources of variance in step counts and to examine the minimum number of days required to obtain a stable measure of habitual ambulatory activity in the cerebral palsy (CP) population.


METHODS
Cross-sectional.


METHODS
Free-living environments.


METHODS
Children and adolescents with CP (N=209; mean age ± SD, 8y, 4mo ± 3y, 4mo; n=118 boys; Gross Motor Function Classification System [GMFCS] levels I-III) were recruited through 3 regional pediatric specialty care hospitals.


METHODS
Daily walking activity was measured with a 2-dimensional accelerometer over 7 consecutive days. An individual information-centered approach was applied to days with <100 steps, and participants with ≥3 days of missing values were excluded from the study. Participants were categorized into 6 groups according to age and functional level. Generalizability theory was used to analyze the data.


METHODS
Mean step counts, relative magnitude of variance components in total step activity, and generalizability coefficients (G coefficients) of various combinations of days of the week.


RESULTS
Variance in step counts attributable to participants ranged from 33.6% to 65.4%. For youth ages 2 to 5 years, a minimum of 8, 6, and 2 days were required to reach acceptable G coefficient (reliability) of ≥.80 for GMFCS levels I, II, and III, respectively. For those ages 6 to 14 years, a minimum of 6, 5, and 4 days were required to reach stable measures of step activity for GMFCS levels I, II, and III, respectively.


CONCLUSIONS
The findings of the study suggest that an activity-monitoring period should be determined based on the GMFCS levels to reliably measure ambulatory activity levels in youth with CP.
Department of Health and Human Performance, Middle Tennessee State University, Murfreesboro, TN, USA. si2p@mtmail.mtsu.edu
Saori
S
Ishikawa
Minsoo
M
Kang
Kristie F
KF
Bjornson
Kit
K
Song
D000293:Adolescent; D002547:Cerebral Palsy / Q000503:physiopathology*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004185:Disability Evaluation; D019988:Children with Disabilities; D005260:Female; D020233:Gait Disorders, Neurologic / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic