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: To develop age- and sex-standardised scores for the Parent Report of Children’s Abilities-Revised (PARCA-R) in order to assess children’s cognitive and language development at 24 to 27 months of age. Methods: Anonymised data from PARCA-R questionnaires completed by parents of 2 yearold 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 (non-verbal 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: For all PARCA-R scales, mean (SD) standardised scores approximated 100 (15) in both sexes and all age groups. These were independent of socio-economic status. Standardised scores were close to 100 (15) in the external validation sample, demonstrating the validity of the scores. Children born very preterm or with neonatal sepsis had, respectively, standardised scores for the total PRC scale 0.47 SD and 0.73 SD lower on average than the normative mean. These were equivalent to a standardised score of 93 (95% Confidence interval (CI): 91 to 94) and 89 (95% CI: 88 to 91) respectively, thus demonstrating clinical validity. 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.