Early- vs. Late-Presenting First-Episode Psychosis in Oman: A Cluster Analysis of Clinical Subgroups

First-episode psychosis (FEP) is a critical phase in the illness trajectory, where early detection and reduced duration of untreated psychosis (DUP) are strongly associated with improved clinical outcomes. However, substantial heterogeneity exists in how individuals present for initial psychiatric care, and data from the Gulf region remain limited.

To identify clinically relevant subgroups of FEP patients in Oman using a data-driven clustering approach and to explore factors associated with treatment delays.

This retrospective exploratory study reviewed electronic medical records of antipsychotic-naïve FEP patients presenting to Sultan Qaboos University Hospital, Muscat, from January 2010 to December 2020. Age, gender, neurological examination results, and DUP (standardized to days) were extracted. K-means clustering was applied to identify latent patient subgroups, with the optimal solution selected using silhouette coefficients. Descriptive comparisons were then conducted to characterize cluster differences.

A total of 121 patients met inclusion criteria. Two clusters were identified (average silhouette ≈ 0.46). Cluster 1 comprised younger patients with short DUP (median 20 years; DUP≈30 days), whereas Cluster 2 represented older patients with markedly prolonged DUP (median 39 years; DUP≈60 days), with 39% experiencing delays > 6 months and 27% > 1 year. Cluster 2 showed a higher frequency of schizophrenia-spectrum diagnoses. Age and DUP differed significantly between clusters (p < 0.001 and p = 0.004), whereas gender distribution, neurological abnormalities, and neuroimaging findings were comparable (p > 0.05 for all).

FEP patients in Oman appear to separate into a younger, early-presenting subgroup and an older subgroup experiencing substantial treatment delays. These findings indicate that delayed access to care is driven more by sociodemographic and illness-course factors than neurological pathology. Enhancing early recognition pathways, particularly for later-onset or insidious presentations, may help reduce DUP and improve long-term outcomes.