Longer Duration of Untreated Psychosis is Associated with Poorer Outcomes for Patients with Delusional Infestation

We examined the association between the duration of untreated psychosis and outcome for patients with delusional infestation. This multi-centre international study included 211 consecutive patients. Illness severity was evaluated at first presentation and outcome was measured with the Clinical Global Impression scale (CGI) at baseline and follow-up. A regression analysis showed a clear clinical and statistically significant association between shorter duration of untreated psychosis and better outcome at follow-up. Patients with a duration of untreated psychosis of less than one year showed a CGI-S change from 5.37 to 2.07; those with a duration of untreated psychosis of 1-5 years a change from 5.48 to 2.59, and those with a duration of untreated psychosis of > 5 years a change from 5.59 to 3.37. This difference of 1.1 CGI points between the groups resembles a clinically relevant difference in patient outcome. Our results suggest that longer duration of untreated psychosis in patients with delusional infestation is associated with significantly less favourable clinical outcomes.