The validity of proxy-based data in suicide research: a study of patients 50 years of age and older who attempted suicide. 1. Psychiatric diagnoses

Objective: To investigate the validity of best-estimate methodology for mak ing psychiatric diagnoses among individuals who attempted suicide. Method: Subjects were 80 patients admitted for treatment following a suicid e attempt. Psychiatric diagnoses based on structured interviews with subjec ts were compared with diagnoses made based on interviews with proxy respond ents. In both cases, interview information was supplemented with pre-admiss ion 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 f or substance dependence but poor For substance abuse disorders. Conclusion: Results support best-estimate methodology for making mood and s ubstance dependence diagnoses in research of suicidal behavior in this age group, with potential implications for interpreting postmortem research of completed suicide.