Abstract
Administrative data have been used to determine the occurrence of suicide attempts and deliberate self-harm, but research about the accuracy of these sources is limited. This study used a clinical sample (n = 5719) containing psychiatry consultations from the emergency departments and inpatient units of the two major tertiary hospitals in Winnipeg, Canada to validate the accuracy of inpatient hospital diagnosis codes at identifying presentations for self-harm and suicide attempts. The Columbia Classification Algorithm of Suicide Assessment (C-CASA) was used as the gold standard. International Classification of Diseases version 10 Canadian Enhancement codes for intentional self-harm, undetermined intent self-harm, and accidental poisoning were assessed. Measures of validity included Kappa (κ), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV). Sensitivity of hospitalized attempts was low using intentional intent codes (36.9%, 95% confidence interval [CI]: 32.4-41.4%) but improved using unknown intent and accidental poisoning codes (44.8%, 95% CI: 40.2-49.4%). Agreement for suicide attempts did not increase with the addition of unknown intent and accidental poisoning codes (κ = 0.465-0.481), but were better for any self-harm (κ = 0.395-0.478). Hospital diagnosis codes undercount attempts and self-harm admissions. Including more data sources might improve the detection of events.