Design, sample and setting
This cross-sectional questionnaire was conducted in a prefecture-level city in China from April 7 to May 10, 2020. According to the local area division, the city has 13 districts, counties (cities) and 2 functional areas. The researchers tried to contact all patients with schizophrenia registered with the local health system, and finally obtained 17,212 questionnaires from patients with schizophrenia. After excluding invalid data, 15,165 questionnaires were available for analysis.
We designed the content of the questionnaire. Community-dwelling patients with schizophrenia under their respective management were contacted by physicians, practicing mental illness prevention in respective districts, counties, and county-level cities, by means of telephone calls, door-to-door visit and outpatient visits, and then physicians filled out online after obtaining the information. Before the start of the study, we trained local physicians, detailing the questionnaire items and quality control of data collection. During the investigation process, the physicians was responsible for explaining the purpose of the study and introducing the content of the questionnaire to ensure that the participants fully understood.
Inclusion criteria were: living in China, being able to communicate normally and meeting the Diagnostic and Statistical Manual of Mental Disorders IV (DSM-IV) diagnosis of schizophrenia. Excluding criteria were: in the acute phase of schizophrenia,accompanying serious medical illness. The 15165 subjects included 7010 male participants (46.2%) and 8155 female participants (53.8%). Age ranged from 10 to 96 years old, and mean age was 55.4 years ± 13.9 S.D.
Ethical approval
The study complied with the ethical standards of the Declaration of Helsinki and was approved by the Ethics Committee of Hangzhou Seventh People’s Hospital. All participants provided written informed consent. Subjects who communicated face-to-face signed a paper informed consent form, and those who communicated by phone signed an electronic informed consent form through an online platform. Because the participants in this study included minors, informed consent was obtained from their parents and/or legal guardians.
Measures
All participants completed a detailed questionnaire, including demographic data, anxiety and depression assessments, and some other information (see supplementary material for details), including sleep status, other accompanying long-standing diseases, concerning about the COVID-19. We defined " long-term diseases “ and explained " sleep status" and “concerning about the COVID-19” in the supplementary material 1.
The Generalized Anxiety Disorder-7 (GAD-7) was adopted to assess the severity of self-reported anxiety[16]. It is composed of 7 items to evaluate how often over the past two weeks the patient has suffered from various issues, such as “difficulty in relaxing” or “excessive worry”. Response categories are “not at all”, “several days”, “more than one week”, and “nearly every day”, scored as 0, 1, 2, and 3, respectively. The total score of the GAD-7 is calculated by summing each item score. The total score ranges from 0 to 21, with a score of 5 indicating that the patient has anxiety. A score of 5, 10, and 15 represent the threshold for “mild”, “moderate”, and “severe” anxiety respectively. Studies showed that the scale has good internal consistency (Cronbach’α=0.92), and the test-retest reliability coefficient was 0.83. When the decomposition value was 10 points, the sensitivity was 89% and the specificity was 82%[17].
PHQ-9, also with good reliability and validity, was employed to screen depressive disorder and measure the severity of symptoms[18]. PHQ-9 is made up of 9 items to evaluate how often over the past two weeks the patient has suffered from nine issues, including depressed mood and anhedonia. Response categories are “not at all”, “several days”, “more than one week”, and “nearly every day”, scored as 0, 1, 2, and 3, respectively. The total score ranges from 0 to 27, with a score of 5 indicating that the patient has depression. A score of 5, 10, 15, and 20 represent the threshold for “mild”, “moderate”, “severe”, and “extremely severe” depression respectively. Nine items of PHQ-9 include anhedonia, depressed mood, sleep disturbance, fatigue, appetite changes, low self-esteem, concentration problems, psychomotor disturbances, and suicidal ideation.
Statistical analysis
Data analyses were conducted using IBM SPSS Statistics software version 19.0 (IBM Corporation, Armonk, NY, USA). Categorical data were described in the case number (percentage) and quantitative data in mean score ± S.D. Group comparison was conducted by t-test, ANOVA, or chi-square test wherever suitable, and pairwise comparison was conducted by Bonferroni test. In order to look for the score differences of PHQ-9 and GAD-7, patients with schizophrenia were sub-grouped into six groups by demographic and clinical status, namely sex, age, marital status, educational level, sleep status, and other accompanying long-standing diseases. Multivariate logistic regression models were performed to identify independent predictors for anxiety and depression respectively. GAD-7 and PHQ-9 scores were first transformed into binary variables with the threshold of mild anxiety or depression and then served as dependent variables in the respective regression models. Sex, age, marital status, educational level, sleep status, other accompanying long-standing diseases, concerning COVID-19, and the degree of concern about the COVID-19. of COVID-19 served as independent variables. Statistical significance was set at a two-sided P-value < 0.05.