Validity and reliability of the new NIMHANS intellectual disability screening instrument (NID-Screener) for children and adolescents in India.

Introduction: There is a gap in tools specifically designed for assessing Intellectual Disability (ID) in Indian settings. To address this, the NIMHANS intellectual disability screening instrument (NID-Screener) was developed by the Department of Child and Adolescent Psychiatry, National Institute of Mental Health and Neuro Sciences.

Methods: Ten non experts/language and ten experts rated face and content validity of NID-Screener respectively. Content validity was measured by Content Validity Ratio, Content Validity Indices (I-CVI, S-CVI) and Modified Kappa statistics. Construct validity was calculated by performing Exploratory Factor Analysis(EFA) on responses from 275 parent(s)/guardian(s) of children and adolescents (6-17 years). Criterion Validity was tested against Brief Intellectual Disability Scale (BIDS) and Clinical Diagnosis by Child and Adolescent Psychiatrist. Kappa Statistics was used to calculate inter - method and inter-Rater Reliability. Cronbach's alpha was used to assess Internal Consistency. This study was approved by NIMHANS ethics committee.

Results: Findings revealed that NID-Screener has good face and content validity (S-CVI/Average = 0.917). Criterion Validity was excellent (Kappa Value=0.862, p-value<0.001) when compared with BIDS. Sensitivity and specificity were found to be 84.7 %, 89 % respectively against Clinical Diagnosis. On EFA, only one underlying factor with Eigen value > 1 was identified (55.8 % of total variance). Kappa value was found to be 0.971 and 0.942 for inter- rater and inter -method reliability respectively(p-value<0.001). NID-Screener has good internal consistency [Cronbach's alpha = 0.841].

Conclusions: NID-Screener is a reliable and valid tool for screening ID among children and adolescents in India, facilitating its early detection through diagnostic assessments and subsequent interventions.