Comparison of clinical features and 1‐year outcomes between patients with psychotic disorder not otherwise specified and those with schizophrenia

Aim Research on psychotic disorder not otherwise specified (PNOS) that clearly mentions its subgroups is very rare. This study was conducted to identify the demographic and clinical features, cognitive function, and 1‐year outcomes of patients with early stage PNOS compared with those with early stage schizophrenia (SZ). Methods The study subjects were 54 and 321 patients with PNOS and SZ, respectively, who were registered at least more than 1 year ago. Due to drop out, only 37 and 210 patients with PNOS and SZ were evaluated at the 1‐year follow‐up. We compared clinical variables (duration of untreated psychosis, symptom severity, self‐rating scales, and so on), cognitive function, and short‐term outcomes (treatment response, remission, compliance, drop out, relapse) between the two groups. Results The patients with PNOS were associated with higher diagnostic stability (53.7%) compared with those in previous studies. They had lower symptom severity, better treatment response at 2 months and higher remission rates at 12 months, but poorer compliance at 6 months compared with patients with SZ. Level of cognitive impairment in PNOS was intermediate between those of SZ patients and healthy controls. Conclusions These findings indicate that PNOS has unique clinical features, suggesting that it should be treated as a distinct clinical syndrome. At the same time, however, prevention of its possible progression to other psychotic disorders in some patients with PNOS is also important.