Validity of proxy-based reports of impulsivity and aggression in Chinese research on suicidal behavior.

Background: In studies about the risk factors for suicidal behavior, the assessment of impulsiveness and aggression often depend on information from proxy informants. Aims: To assess the validity of proxy informants' reports on impulsiveness and aggression in China. Methods: Modified Chinese versions of the Barratt Impulsiveness Scale (BIS-CV) and the Buss-Perry Aggression Questionnaire (AQ-CV) were administered to 131 suicide attempters treated at a hospital in rural China, to coresident relatives about the attempters, to 131 matched community controls, and to coresident relatives about the controls. Results: BIS-CV and AQ-CV total scores and subscale scores were all significantly higher for suicide attempters than for matched controls. Proxy informants considered subjects slightly more impulsive and aggressive than the subjects reported themselves. Subject-proxy concordance for total BIS-CV and AQ-CV scores were excellent for both attempters and controls ( ICCs = 0.76-0.83). Concordance for the three BIS-CV subscales was 0.74-0.81 for attempters and 0.74-0.83 for controls. Concordance for the five AQ-CV subscales was 0.66-0.85 for attempters and 0.56-0.82 for controls. Limitations: Results are based on respondents from a single location in rural China. Conclusions: The results support the validity of the BIS-CV and AQ-CV and of research on suicidal behavior in China that uses proxy-based reports of impulsiveness and aggression.