Patients presenting with first-episode delusional disorder have less severe symptomatology and better prognosis at baseline compared with patients with schizophrenia, according to results of a nested case control study published in Schizophrenia Research. However, both groups were found to demonstrate similar symptomatic and functional improvement over the short term.
Investigators designed a nested case-control study within the National EDEN study, which comprised 1027 patients with first-episode psychosis admitted to early intervention services in the United Kingdom between August 2005 and April 2009. EDEN study patients were assessed at baseline and at 6 and 12 months for symptomatic and functional outcomes, including Positive and Negative Syndrome Scale (PANNS) score and Global Assessment of Functioning (GAF) symptoms, disability, and total score. Sociodemographic characteristics and duration of untreated psychosis were also captured at baseline.
Of the 815 patients included in the nested case-control design, 48 (5.9%) had a diagnosis of delusional disorder and 262 (94.1%) had a diagnosis of schizophrenia. No substantial demographic differences were observed between study groups, though a significantly larger proportion of patients with delusional disorder reported paid employment (29.8%) compared with patients with schizophrenia (13%) (P =.004). Mean duration of untreated psychosis was also significantly shorter in those with delusional disorder (135.8 days; 95% CI, 66.5-205.1) than in those with schizophrenia (330.2 days; 95% CI, 248.8-411.7; P <.001). Individuals with delusional disorder had better functioning at baseline as reflected by GAF total (P =.036), GAF symptom (P =.02), and GAF disability (P <.001) scores compared with the schizophrenia group. Baseline PANSS mean scores were significantly lower for the delusional disorder group compared with the schizophrenia group for the positive (P =.023), negative (P =.008), general psychopathology (P =.049), and total (P =.009) subsections.
At 12 months, the differences in symptom scores persisted, with PANSS mean scores in the positive (P =.01), negative (P <.001), general (P =.014), and total (P =.001) subsections significantly lower for patients with delusional disorders vs those with schizophrenia. However, at 12 months the between-group differences in functioning were not significant as per the GAF total score. Additionally, once adjusted for baseline characteristics, no significant between-group differences were observed at 12 months for PANSS positive score, any GAF subsection score, or likelihood of relapse. In the adjusted model, however, individuals with delusional disorder still had significantly higher rates of recovery (P =.002).
These data support the consideration of delusional disorder as a separate diagnostic entity from schizophrenia. However, further research is necessary to elucidate the disease course of delusional disorder and identify long-term functional outcomes beyond 12 months.
Rowland T, Birchwood M, Singh S, et al. Short-term outcome of first episode delusional disorder in an early intervention population [published online September 05, 2018]. Schizophr Res. doi: 10.1016/j.schres.2018.08.036