Gender of parental respondents and irritability ratings on the affective reactivity index in Japanese children

Information on child irritability varies by informant, yet little is known about how ratings differ between male and female parent respondents, and psychometric evidence for father-reported irritability is scarce. This study evaluated the psychometric properties and measurement invariance of the Japanese Affective Reactivity Index Parent-Report Form (ARI-p) across parent respondent gender groups, then examined group differences and their interactions with sociodemographic variables. In a two-wave community-based online panel survey, 4,800 parents (2,633 male and 2,167 female parent respondents) of children aged 6–18 years completed the ARI-p, the Strengths and Difficulties Questionnaire (SDQ), and demographic questions; 3,847 (80.1%) completed a follow-up after two months. The ARI-p showed good internal consistency (α = 0.885, 95% CI [0.880, 0.890]) and moderate test-retest reliability (ICC = 0.570, 95% CI [0.548, 0.591]). Approximate configural, metric, and scalar measurement invariance was supported, with qualifications including an elevated RMSEA. The ARI-p correlated positively with SDQ Emotional Symptoms (ρ = .46) and modified Conduct Problems (ρ = .50), and each one-point increase was associated with higher odds of a parent-reported disruptive mood dysregulation disorder classification (OR = 1.53, 95% CI [1.41, 1.65]). Score distributions were similar between the two respondent groups (p = .211); after adjusting for sociodemographic variables, male parent respondents reported slightly higher scores (B = 0.32, 95% CI [0.15, 0.48], p < .001), with no statistically detectable gender-by-sociodemographic interactions (p = .541). The Japanese ARI-p is reliable and valid for community samples, and the gender of parental respondents merits consideration when interpreting irritability ratings.