The validity of proxy-based data in suicide research: a study of patients 50 years of age and older who attempted suicide. I. Psychiatric diagnoses.

OBJECTIVE

To investigate the validity of best-estimate methodology for making psychiatric diagnoses among individuals who attempted suicide.

METHOD: Subjects were 80 patients admitted for treatment following a suicide attempt. Psychiatric diagnoses based on structured interviews with subjects were compared with diagnoses made based on interviews with proxy respondents. In both cases, interview information was supplemented with pre-admission psychiatric and medical records to inform diagnoses.

RESULTS

Diagnostic agreement, based on kappa coefficients, was substantial for major depression and bipolar disorders, and moderate for non-affective psychoses, organic mood and anxiety disorders. Agreement was substantial for substance dependence but poor for substance abuse disorders.

CONCLUSION

Results support best-estimate methodology for making mood and substance dependence diagnoses in research of suicidal behavior in this age group, with potential implications for interpreting postmortem research of completed suicide.