Standardisation of the Parent Report of Children’s Abilities-Revised (PARCA-R): a norm-referenced assessment of cognitive and language development at 2 years of age

Background: The Parent Report of Children's Abilities–Revised (PARCA-R) can be used to identify preterm born children at risk for developmental delay at age 24 months. However, standardised scores for assessing all children in the general population and quantifying development relative to the norm are unavailable, thus limiting the use of the questionnaire. We aimed to develop scores that are standardised by age and sex for the PARCA-R to assess children's cognitive and language development at age 24–27 months. Methods: Anonymised data from PARCA-R questionnaires completed by parents of 2 year-old children in three previous studies were obtained to form a standardisation sample (n=6402) representative of the UK general population. Anonymised data were obtained from three further studies to assess the external validity (n=709) and clinical validity (n=1456) of the standardised scores. The L(lamda)M(mu)S(sigma) method was used to develop age- and sex-specific standardised scores for three scales (nonverbal cognitive development; language development; total Parent Report Composite (PRC)) for children in four 1-month age bands spanning 23·5 to 27·5 months of age. Findings: We included 6402 children (mean age 25 months and 1 day [range 23 months and 16 days to 27 months and 15 days]) in the standardisation sample and 709 (mean age 24 months and 19 days [23 months and 16 days to 27 months and 15 days]) to test the external validity and 1456 (mean age 24 months and 8·5 days [23 months and 16 days to 27 months and 15 days]) to test the clinical validity of the standardised scores. For all PARCA-R scales, mean standardised scores approximated 100 (SD 15) in both sexes and all age groups. These scores were independent of socioeconomic status. Standardised scores were close to 100 (15) in the external validation sample, showing the validity of the scores. Standardised scores for the total PRC scale for children born very preterm ( Interpretation: The PARCA-R provides a norm-referenced, standardised assessment of cognitive and language development at 24-27 months of age. The questionnaire is available non-commercially with translations currently available in 14 languages, thus providing clinicians and researchers with a cost-effective tool for assessing development and identifying children with delay.