Prevalence of schizophrenia and its association with socio-demographic correlates in an agricultural region of China

Highlights

• Few studies have estimated the prevalence and correlates of schizophrenia in agricultural regions of China.

• The weighted one-month and lifetime prevalence of schizophrenia were 0.5 % and 0.6 %, respectively.

• The prevalence of schizophrenia in Hebei province appears lower than in most areas of China and other countries.

Abstract

Little is known about the epidemiology of schizophrenia in the agricultural regions of China. This study examined the 1-month and lifetime prevalence of schizophrenia and their association with socio-demographic factors in Hebei province which is an important agricultural region of China. A multi-stage, stratified, cluster random sampling method was adopted. The diagnosis of schizophrenia was ascertained with the validated Structured Clinical Interview for DSM-IV Axis I Disorders-Patient Edition (SCID-I/P/C). Altogether, 23,675 subjects were screened, of whom, 20,884 were included for analyses. The weighted 1-month and lifetime prevalence of schizophrenia were 0.5 % [95 % confidence interval (CI): 0.4–0.5 %] and 0.6 % (95 %CI: 0.5–0.7 %), respectively. Multiple logistic regression analyses found that unmarried marital status [P < 0.001, Odd Ratio(OR)=2.670, 95 %CI:1.767−4.036], lower education level (primary school or below: P = 0.042, OR=2.447, 95 % CI: 1.034−5.933; secondary school: P = 0.002, OR = 4.261, 95 % CI:1.692−10.730), unemployment (P = 0.006, OR=1.870, 95 % CI:1.198−2.920), lower income (P < 0.001, OR=4.017, 95 % CI:2.207−7.310) and family history of psychiatric disorders (P < 0.001, OR=16.278, 95 % CI:10.435−25.393) were independently associated with a higher risk of schizophrenia, while age above 60 years (P = 0.004, OR=0.440, 95 % CI:0.253−0.765) was associated with a lower risk of schizophrenia. The prevalence of schizophrenia appeared to be lower in Hebei province compared to other regions of China or other countries. Socioeconomic factors should be further examined to inform the public health surveillance and policies relevant to schizophrenia in the agricultural regions of China.

Introduction

Schizophrenia is a major psychiatric disorder globally (Bloomfield et al., 2016), and a leading cause of disability and health economic burden (Vos et al., 2015). A systematic review found that the economic burden of schizophrenia represented between 0.02 % and 1.65 % (i.e., US$94 million-US$102 billion) of the gross domestic product (GDP) (Chong et al., 2016). Another study found that the economic burden caused by schizophrenia accounted for 1.7 % of the total years of life lived with disability (YLD) globally (Charlson et al., 2018). In order to reduce the economic burden and improve the prognosis of schizophrenia, it is important to understand the epidemiology of schizophrenia and its correlates.

In previous decades, prevalence studies of schizophrenia have found wide variation across different countries and regions (Ayano et al., 2019; Jablensky, 2000). For example, the point prevalence of schizophrenia was 0.7 % in the USA (Bland, 1992), 0.31 %-0.59 % in Australia (Jablensky et al., 2000), 0.14 % in Indonesia (Salan, 1992) and 0.68 % in Kosrae (Waldo, 1999); while the lifetime prevalence of schizophrenia was 1.5 % in the USA (Bland, 1992), 0.3 %-0.4 % in Korea (Lee et al., 1990) and 0.12 %-0.13 % in Hongkong (Chen et al., 1993). Moreover, the twelve-month prevalence of schizophrenia was 0.51 % in the USA (Wu et al., 2006), 0.40–0.52 % in Korea (Cho et al., 2020) and 0.29 %-0.30 % in Spain (Ayuso-Mateos et al., 2006). The discrepancy of the findings between studies could be partly attributed to different methodologies (e.g., sampling and diagnostic instruments) and sociocultural and economic factors.

In China, a systematic review of epidemiological studies found that the point prevalence of schizophrenia in urban areas increased from 0.32 % (95 % CI = 0.29–0.36 %) in 1990, to 0.47 % (95 % CI = 0.44–0.50 %) in 2000, and 0.68 % (95 % CI = 0.57–0.81 %) in 2010. In contrast, the corresponding figures in rural areas decreased from 0.37 % (95 % CI = 0.33–0.42 %) in 1990, to 0.36 % (95 % CI = 0.35–0.38 %) in 2000, and 0.35 % (95 % CI = 0.33– 0.38 %) in 2010. Similarly, the lifetime prevalence in urban areas increased from 0.39 % (95 % CI = 0.37–0.41 %) in 1990, to 0.57 % (95 % CI = 0.55–0.59 %) in 2000 and 0.83 % (95 % CI = 0.75–0.91 %) in 2010. Nevertheless, the corresponding figures in rural areas also increased from 0.37 % (95 % CI = 0.34–0.40 %) in 1990, to 0.43 % (95 % CI = 0.42–0.44 %) in 2000 and 0.50 % (95 % CI = 0.47–0.53 %) in 2010 (Chan et al., 2015a, b). To date, relatively few studies on the epidemiology of schizophrenia or its changing trends have been conducted in agricultural regions of China. An early study conducted in Hebei province (Li et al., 2007), which is a predominantly agricultural region in China, found that the 1-month and lifetime prevalence of schizophrenia was 0.55 % and 0.66 %, respectively. The dramatic socio-economic changes in China in recent decades (Zhu et al., 2011) may have influenced the epidemiological patterns of mental disorders in China. Hence, we examined the 1-month and lifetime prevalence of schizophrenia in the adult population in Hebei province and explored their socio-demographic and clinical correlates.