The association between season of birth, age at onset, and clozapine use in schizophrenia

Abstract

Our results indicate that the age at onset is an important factor in predicting the prognosis of schizophrenia patients. The season of birth also affects the prognosis, but with less robustness. Specifically, it appears that early disease onset and winter birth might be associated with poor outcomes in Korean patients with schizophrenia.

Predictors of treatment resistant schizophrenia: a systematic review of prospective observational studies

“…Additional analyses of Wimberley et al (2016b)'s data tested whether urbanicity (Wimberley et al, 2016a), the polygenic risk score for schizophrenia (PRS-SZ; Wimberley et al, 2017), functioning (Horsdal et al, 2017b), and C-reactive protein levels (Horsdal et al, 2017a) could predict TRS. The third population cohort came from South Korea (Kim et al, 2017). The remaining five studies analysed longitudinal first episode psychosis patient cohorts (Meltzer et al, 1997;Chan et al, 2014;Lally et al, 2016;Üçok et al, 2016;Demjaha et al, 2017).…”

“…Immonen et al (2017) found that males had a younger age of onset and, therefore, samples with a higher proportion of males tended to show stronger associations between age of onset and outcomes. In the studies included in this review, the association between age of onset and TRS is unlikely to be wholly confounded by gender, as the proportion of males ranged from 49% (Kim et al, 2017) to 67% (Lally et al, 2016) and the studies which controlled for gender still showed an effect of age of onset (Meltzer et al, 1997;Lally et al, 2016;Wimberley et al, 2016b;Demjaha et al, 2017). In schizophrenia, age of onset has been thought to reflect genetic liability for the disease; younger age of onset has been associated with an increased familial risk of schizophrenia (Hilker et al, 2017;Byrne et al, 2018).…”

“…Demjaha et al (2017) reported a McFadden's pseudo R 2 of 0.10 and a Brier score of 0.146, suggesting that their model is not a good fit of the data nor is it a good classifier of TRS. Kim et al (2017), in their South Korean population cohort, estimated the cumulative incidence of clozapine use using the Kaplan-Meier method and log-rank test. They reported that younger age of onset predicted TRS.…”

“…Unlike Chan et al (2014) and Demjaha et al (2017), Kim et al (2017) examined age of onset categorically: defining younger age of onset as those aged between 15-20 years of age, and comparing them to a middle-onset group (21-44 years of age) and a late-onset group (45-64 years of age). Kim et al (2017) also found, using the Walter-Elwood method (Walter and Elwood, 1975), a higher incidence of clozapine use, in those born during winter (December to February) when compared to those born in summer (June to August). This pattern remained true when stratifying season of birth by age of onset.…”

“…This pattern remained true when stratifying season of birth by age of onset. Kim et al (2017) reported no measures of overall model fit.…”