Impaired Insight Into Delusions Predicts Treatment Outcome During a Randomized Controlled Trial for Psychotic Depression (STOP-PD Study)

Background: Insight into delusional beliefs varies in patients with major depressive disorder (MDD) with psychotic features (“psychotic depression”). The relationship between impaired insight and illness severity and its impact on treatment outcomes has not been studied in psychotic depression. As such, the aim of this analysis was to explore the relationship among impaired insight, patient characteristics (ie, illness severity, cognition, suicidality, and social functioning), and treatment outcome (ie, remission) during acute treatment of psychotic depression.

Method: This secondary analysis is based on the data from the Study of Pharmacotherapy for Psychotic Depression (STOP-PD) in which 259 participants meeting DSM-IV criteria for MDD with psychotic features enrolled between December 2002 and June 2007 (including 142 aged ≥ 60 years) in a 4-center, 12- week, double-blind, randomized controlled trial funded by the US National Institutes of Health. Insight into delusions was assessed using the Delusion Assessment Scale (DAS). The primary outcomes were the predictive utility of insight into illness (ie, Hamilton Depression Rating Scale [HDRS] insight item) and insight into delusions (conviction factor derived from the DAS) on final treatment outcome at 12 weeks of treatment (ie, full remission, partial remission, and nonremission).

Results: At baseline, impaired insight into delusions was positively associated with illness severity (HDRS-16 which excluded the insight item, r = 0.15, P = .016) and negatively correlated with measures of cognition (P < .05). Improvement in insight was not associated with changes in cognition, suicidality, or social functioning after adjusting for covariates. Independent of the severity of depression or psychosis, impaired insight into delusions at baseline (χ2 = 11.65, P = .020) and after 3 (χ2 = 9.62, P = .047), 6 (χ2 = 6.97, P = .031), and 8 (χ2 = 9.08, P = .011) weeks of treatment predicted remission at the end of the trial.

Conclusions: Impaired insight into delusions appears to be an independent predictor of remission in MDD with psychotic features during acute treatment, suggesting that more attention should be paid to this symptom. Longitudinal studies are required to determine the impact of impaired insight into delusions on long-term outcomes, including relapse.

Trial Registration: ClinicalTrials.gov identifier: NCT00056472