Cross-ethnic differences in severity of symptomatology of individuals with first-episode schizophrenia spectrum disorder

Abstract

Aims: The aims of this study were to describe the relationship between ethnicity and severity of baseline symptomatology in a sample of Asian individuals with first-episode schizophrenia spectrum disorder, and to determine if ethnicity predicts severity of symptomatology independent of gender, duration of untreated illness, premorbid functioning, and age of illness onset.

Methods: This descriptive study included all Chinese, Malay and Indian individuals consecutively admitted into an early intervention programme for treatment of first-episode schizophrenia spectrum disorder. Comparisons of mean scores among the three ethnic groups were performed using analysis of variance, while chi-squared tests were used to compare proportions. Subsequent pair-wise comparisons were performed with Bonferroni corrected statistic to examine specific ethnic group differences. Multivariate regression analyses were conducted to identify factors significantly associated with the severity of different clinical dimensions of schizophrenia measured using the Positive and Negative Syndrome Scale (PANSS).

Results: The analyses involved 503 individuals. The mean PANSS scores were significantly different between the ethnic groups across the PANSS subscales. A post-hoc analysis showed that Malays scored significantly higher than Chinese did across the PANSS subscales. Malays also scored significantly higher than Indians did on the negative scale and the general psychopathology scale. Being Malay compared with Chinese consistently predicted more severe positive, negative and general psychopathology symptoms.

Discussion: The results indicated that the severity of baseline symptomatology of individuals with first-episode schizophrenia spectrum disorders differed by ethnicity. Premorbid functioning appears to act as a potential mediator of the effects of ethnicity on the severity of psychotic symptoms.