Investigation of fine motor performance in children younger than 36-month-old using PDMS-2 and Bayley-III

The aim of the study was to investigate the concurrent validity of fine motor (FM) development scores between the Peabody Developmental Motor Scales, Second Edition (PDMS-2), and Bayley Scale of Infant and Toddler Development, Third Edition (Bayley-III). Both tests were administered to 223 children aged 13–36 months with suspected developmental delays from a medical centre. Concurrent validity and agreement of FM delay were assessed. The Bayley-III FM scale scores (FMSS) and motor composite quotients were moderately correlated with PDMS-2 FM quotients. The agreement of FM delay between the two instruments was excellent (Kappa coefficient value =.80) in children aged 13–18 months and good in children aged 19–36 months. When using PDMS-2 as the reference standard, Bayley-III (FMSS < 7) identified fewer children aged 19–24 months as delayed but more in children aged 25–36 months as delayed. When adjusting the cut-off point of Bayley-III FMSS to 8 for children aged 19–24 months and to 6 for children aged 25–36 months, the agreement improved between these two instruments. FM delays might be underestimated solely using Bayley-III in children aged 19–24 months. Additional tests, such as PDMS-2 should be considered to avoid delays in accessing early intervention services.