Prognostic significance of psychotic relapse in patients with first-episode acute and transient psychosis: New empirical support for ICD-11.

This study examined the impact of psychotic relapse on the diagnostic stability of acute and transient psychotic disorders (ATPD), and how this potential risk factor could differentiate 'acute polymorphic psychotic disorder without symptoms of schizophrenia' (APPD; ICD-10 code F23.0) from the remaining non-APPD subtypes (F23.1-9). A two-year cohort study was performed on 68 patients with first-episode ATPD. At the end of follow-up, the diagnostic stability of ATPD was 55.9% and the overall rate of psychotic relapse was 61.8%. Statistical analysis showed that recurrence was an independent risk factor for diagnostic shift in ATPDs (relative risk [RR] = 1.67, 95% confidence interval [CI] = 1.17-2.39; p = 0.005) and that this risk differed among their subtypes insofar as its appearance significantly increased the likelihood of diagnostic change in patients with non-APPD subtypes (RR = 2.52, 95% CI = 1.56-4.07; p < 0.001), but not in those with APPD (RR = 0.95, 95% CI = 0.57-1.57; p = 0.844). Our findings confirm the negative implications of recurrence in patients with ATPD, encourage long-term intervention targeting relapse prevention in this population, and provide new empirical evidence in support of narrowing the ATPD category to APPD in the upcoming ICD-11.