Personality is linked to important health outcomes, but most prior studies have relied on self-reports, making it possible that shared-method variance explains the associations. The present study examined self- versus informant-reports of personality and multi-method outcomes. World Trade Center (WTC) responders and informants, 283 pairs, completed five-factor model personality measures and multi-method assessments of stressful events, functioning, mental disorders, 9/11-related treatment costs, BMI, and daily activity across three years. Self-reports were uniquely related to stressful events and functioning. Both self-reports and informant-reports showed incremental validity over one another for mental disorder diagnoses and treatment costs. For objective outcomes daily activity and BMI, informant-reports showed incremental validity over self-reports, accounting for all self-report variance and more. The findings suggest that informant-reports of personality provide better validity for objective health outcomes, which has implications for understanding personality and its role in mental and physical health.
Keywords: World Trade Center responders; daily activity; healthcare utilization; informant-reports; mental illness; personality; stress.