Measurement invariance of Attention Deficit/Hyperactivity Disorder symptom criteria as rated by parents and teachers in children and adolescents: A systematic review.

This systematic review aimed to establish the extent to which each Attention Deficit/Hyperactivity Disorder (ADHD) symptom criterion is being assessed without being influenced (biased) by factors such as informant, sex/gender, and age. Measurement invariance (MI) testing using confirmatory factor analysis (CFA) is the prime statistical method to ascertain how these factors may affect the measurement and colour the perception or interpretation of symptom criteria. Such effects (non-invariance) can be operationalised in the form of altered association of a symptom criterion with the measured trait (expressed via variations in CFA loadings which represent the weight of each symptom criterion) due to the factor(s) and/or artificially alter the probability of endorsement of a particular symptom criterion (expressed via variations in the CFA threshold(s) representing how mild or severe a given symptom is). Based on a pre-registered protocol (CRD42022276105), we searched PubMed, Global Health, Embase and PsycInfo up to 21-02-23 for studies that included MI assessments on specific ADHD symptom criteria in individuals aged 0-18 years old, using parental and/or teacher report. Self-reports were excluded, given the poor reliability of self-report in ADHD. All included studies met specific COnsensus-based Standards for the selection of health Measurement Instruments (COSMIN) criteria. Results were synthesised in tabular form, grouping results by factors (e.g. informant) from 44 studies retained. Most comparisons indicated both metric (same loadings) and scalar invariance (same thresholds) with regard to informant, gender, age, temporal (repeated assessments) and co-morbidity. Therefore, the available evidence supports the current diagnostic criteria. However, findings could have been improved by systematic reporting of the direction of bias and its effect size. There appears to be a bias towards reporting MI instead of non-invariance. More studies in the literature are needed where the amalgamation of information provided by different informs and the association of specific symptoms with comorbidity are analysed.