Date Presented 04/04/19
This study evaluated the Specific Test of Early Infant Motor Performance (STEP), a rapid screening test of preterm infants at risk for developmental delay. The STEP administered at term and three months showed excellent reliability, required 6 to 10 minutes to administer, and had significant correlations with the Bayley III at 12 months. Although the STEP needs to be validated in a larger cohort, this new rapid assessment may identify infants at risk for delays early in the first three months of life.
Primary Author and Speaker: Patty Coker-Bolt
Additional Authors and Speakers: Dorothea Jenkins
BACKGROUND/PURPOSE: Premature birth is a major risk factor for developmental delays, which may result in a diagnosis of cerebral palsy (CP) at 18-24 months of age or cognitive deficits (1, 2). Eligibility for early intervention monitoring varies by state, but in general, infants must demonstrate significant milestone delays to be referred to OT within the first 12 months. Earlier and more frequent screening could potentially address the well-documented delay in referral and begin to change the orientation of therapy to prevention instead of remediation of deficits. However, we need a rapid, reliable, early developmental screening test and unfortunately, existing tests have low compliance rates (23%) among general pediatricians and therapists (3, 4). The aim of this study was to evaluate the Specific Test of Early Infant Motor Performance (STEP), a new rapid screening test of preterm infants at risk for developmental delay.
DESIGN: We prospectively studied 23 preterm infants’ (<34 months gestational age GA) performance on the STEP and the Test of Infant Motor Performance (TIMP) at term and 3 months correct age (CA), and on the Bayley-III at 12 months. The ten STEP items comprise pull to sit, prone extension, head movement in supine with and without visual stimulation, head movements in supported sitting, supported standing, grasp, rolling elicited by leg and arm, and kicking to assess overall posture and the quality of movement of the head, arms, and legs. A unique feature of the STEP is that each item looks at the quality of movement, not just presence or absence of the motor skill. To investigate the psychometric qualities of the STEP we completed an exploratory factor analysis, used intra-class correlation coefficient (ICC) to determine intra and inter-rater reliability, and used receiver operating characteristics (ROC) curves to determine STEP cutoff scores for low and high performing preterm infants at term and 3-months CA. STEP score at term/3 months served as the continuous variable, Bayley-III gross motor scaled score at 12-months as the dichotomous variable in the ROC curve (low score < 9/high score ≥ 9). To analyze relationships between STEP scores, Bayley composite and scaled scores, and TIMP scores we used Spearman’s rho for nonparametric variables.
RESULTS: 19 infants completed the follow up assessment at 12-months. The latent construct of ‘Head control’ contributes to 68% the STEP variance, while ‘Upper and lower extremity tone and movement’ combined contribute 22% and 12%, respectively, of the variance of STEP scoring. ICC values for inter and inter-rater reliability were excellent (0.91 to 0.95) and the STEP only required 6-10 minutes to administer in a nursery setting. STEP cutoff of < 16 at term yielded a sensitivity of 0.818, specificity of 0.818, negative predictive value of 0.818, and positive predictive value of 0.818. STEP 3-month cutoff of < 22 gave sensitivity of 0.600, specificity of 0.706, negative predictive value of 0.857. STEP scores at term and 3 months significantly correlated with 12-month Bayley-III gross motor and cognitive scaled scores (rs=0.698, p=0.001, rs=0.687, p=0.002 respectively), while TIMP scores did not (rs=0.125, p=0.621, rs=0.418, p=0.075 respectively).
CONCLUSION: STEP is a short, easy to administer, early developmental assessment with unique scoring that emphasizes qualitative and quantitative aspects of muscle tone in movements, and predicts 12-month Bayley gross motor and cognitive scaled scores.
IMPACT STATEMENT: Although the STEP needs to be validated in a larger cohort, this data indicates this new rapid assessment may identify infants at risk for delays early in the first 3-months of life. This would allow for early, targeted OT services which may improve long-term outcomes.
References
1. Donohue PK, Graham EM. Earlier markers for cerebral palsy and clinical research in premature infants. Journal of perinatology : official journal of the California Perinatal Association 2007, 27(5): 259-261.
2. Coker-Bolt P, Woodbury ML, Perkel J, Moreau NG, Hope K, Brown T, et al. Identifying premature infants at high and low risk for motor delays using motor performance testing and MRS. J Pediatr Rehabil Med 2014, 7(3): 219-232.
3. Craciunoiu O, Holsti L. A Systematic Review of the Predictive Validity of Neurobehavioral Assessments During the Preterm Period. Phys Occup Ther Pediatr 2017, 37(3): 292-307.
4. Sand N, Silverstein M, Glascoe FP, Gupta VB, Tonniges TP, O'Connor KG. Pediatricians' reported practices regarding developmental screening: do guidelines work? Do they help? Pediatrics 2005, 116(1): 174-179.
