Prevalence of schizophrenia and its association with socio-demographic correlates in an agricultural region 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.
Section snippets
Subjects and sampling
This was a large-scale cross-sectional study on the epidemiology of schizophrenia in Hebei province, an agricultural region in China (Yuan, 2011; Yuan and Shen, 2013), which is an area where agriculture is the main source of economic development (Bai et al., 2019; Deng et al., 2017). Inclusion criteria were 1) permanent adult residents (i.e., those registered in local household registration system) aged 18 and above in Hebei province, 2) having the ability to communicate and understand the
Participant characteristics
Of the 23,675 participants who were invited to participate in this study, 20,884 met the study entry criteria and completed the assessment, giving a participation rate of 88.2 %. The weighted mean age was 43.83 (SD: 16.6) years and 50.2 % of participants were females. The weighted mean GHQ-12 total score was 0.69 (SD: 1.54). The reasons for those who refused to participate in the study included having no time, failure to understand the contents, and lack of interest.
Table 2 shows the
Discussion
To the best of our knowledge, this was the first epidemiological survey of schizophrenia covering all the 11 administrative regions of Hebei province, China. The study found that the weighted one-month and lifetime prevalence of schizophrenia in Hebei province were 0.5 % and 0.6 %, respectively. In addition, the independent correlates of schizophrenia included marital status, educational level, employment, income and family history of psychiatric disorders.
The lifetime prevalence of
Funding
The study was supported by the Key R&D Program of Science and Technology Department of Hebei Province (172777223).
Contributors
Study design: Wen-Wang Rao, Yun-Shu Zhang, Ke-Qing Li, Yu-Tao Xiang. Data collection, analysis and interpretation: Wen-Wang Rao, Li-Jun Cui, Jian-Feng Li, Lin Li. Drafting of the manuscript: Wen-Wang Rao, Yun-Shu Zhang, Yu-Tao Xiang. Critical revision of the manuscript: Gabor S. Ungvari, Chee H. Ng. Approval of the final version for publication: all co-authors.
Declaration of Competing Interest
The authors report no declarations of interest.
Acknowledgments
The authors would like to thank the mental health professionals and subjects who were involved in the project.
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These authors contributed equally to the work.