An association between autumn birth and clozapine treatment in patients with schizophrenia: A population-based analysis

TY - JOUR

T1 - An association between autumn birth and clozapine treatment in patients with schizophrenia

T2 - A population-based analysis

AU - Sørensen, Holger J

AU - Foldager, Leslie

AU - Røge, Rasmus

AU - Pristed, Sofie Gry

AU - Andreasen, Jesper T

AU - Nielsen, Jimmi

PY - 2014/8

Y1 - 2014/8

N2 - BACKGROUND: Numerous studies on seasonality of birth and schizophrenia risk have been published but it is uncertain whether, among those with schizophrenia, refractory illness exhibits any predilection for birth month. We hypothesized and examined whether a season of birth effect was present in patients with schizophrenia with a history of clozapine treatment.METHOD: Using record linkage with Danish registers, we examined patients with schizophrenia born between 1950 and 1970, and between 1995 and 2009 and Cox regression analysis was used to examine season of birth in relation to history of clozapine treatment.RESULTS: In a study population corresponding to 60,062 person-years from 5328 individuals with schizophrenia of which 1223 (23%) received at least one clozapine prescription, birth in the autumn (September-November) was associated with clozapine treatment (HR = 1.24; 95% CI 1.07-1.46) when compared with birth in the spring (March-May).CONCLUSION: Although replication studies are needed, this is the first evidence from a nationwide study suggesting a possible season-associated risk of clozapine treatment in schizophrenia. The reasons for this relationship remain to be further investigated but might be partially explained by early exposures such as winter flu season and low vitamin D levels.

AB - BACKGROUND: Numerous studies on seasonality of birth and schizophrenia risk have been published but it is uncertain whether, among those with schizophrenia, refractory illness exhibits any predilection for birth month. We hypothesized and examined whether a season of birth effect was present in patients with schizophrenia with a history of clozapine treatment.METHOD: Using record linkage with Danish registers, we examined patients with schizophrenia born between 1950 and 1970, and between 1995 and 2009 and Cox regression analysis was used to examine season of birth in relation to history of clozapine treatment.RESULTS: In a study population corresponding to 60,062 person-years from 5328 individuals with schizophrenia of which 1223 (23%) received at least one clozapine prescription, birth in the autumn (September-November) was associated with clozapine treatment (HR = 1.24; 95% CI 1.07-1.46) when compared with birth in the spring (March-May).CONCLUSION: Although replication studies are needed, this is the first evidence from a nationwide study suggesting a possible season-associated risk of clozapine treatment in schizophrenia. The reasons for this relationship remain to be further investigated but might be partially explained by early exposures such as winter flu season and low vitamin D levels.

KW - Adult

KW - Antipsychotic Agents

KW - Clozapine

KW - Drug Utilization

KW - Female

KW - Humans

KW - Male

KW - Medical Record Linkage

KW - Middle Aged

KW - Risk Assessment

KW - Schizophrenia

KW - Seasons

U2 - 10.3109/08039488.2013.854408

DO - 10.3109/08039488.2013.854408

M3 - Journal article

C2 - 24228775

SN - 0803-9488

VL - 68

SP - 428

EP - 432

JO - Nordic Journal of Psychiatry

JF - Nordic Journal of Psychiatry

IS - 6

ER -