Duration of untreated psychosis and clinical outcomes of first episode psychosis: An observational and an instrumental variables analysis

Aim\ud Duration of untreated psychosis (DUP) is considered a key prognostic variable in psychosis. Yet it is unclear whether a longer DUP causes worse outcomes or whether reported associations have alternative explanations. \ud Methods\ud Data from two cohorts of patients with first episode psychosis were used (n=2134). Measures of DUP were assessed at baseline and outcomes at 12 months. Regression models were used to investigate associations between DUP and outcomes. We also investigated whether any associations were replicated using instrumental variables analysis to reduce the effect of residual confounding and measurement bias.\ud Results\ud There were associations between DUP per 1 year increase and positive psychotic symptoms (7.0% in symptom score increase 95% CI 4.0%,10.0% p