Study objectives: This study aimed to determine the prevalence and the sociodemographic and clinical correlates of insomnia in Chinese schizophrenia outpatients and its impact on patients' quality of life (QOL).
Design: Two hundred fifty-five clinically stable schizophrenia outpatients were randomly selected in Hong Kong and their counterparts matched according to sex, age, age at onset, and length of illness were recruited in Beijing, China. All subjects at both sites were interviewed by the same investigator using standardized assessment instruments.
Setting: Hong Kong and Beijing, China.
Patients or participants: Clinically stable schizophrenia outpatients.
Interventions: N/A.
Measurements and results: In the combined Beijing-Hong Kong sample the frequency of at least one type of insomnia over the previous 12 months was 36.0%; the rates of difficulty initiating sleep (DIS), difficulty maintaining sleep (DMS), and early morning awakening (EMA) were 21.2%, 23.6%, and 11.9%, respectively. Poor sleep was significantly associated with advanced age, older age at onset, fewer psychiatric admissions, severity of positive symptoms, anxiety, extrapyramidal symptoms (EPS) and depressive symptoms, less frequent use of atypical antipsychotic medications (AP), and more frequent use of benzodiazepines (BZD) and hypnotics. Poor sleepers had significantly poorer QOL in all domains than patients without insomnia. After controlling for the potential confounding effects of sociodemographic and clinical factors, a significant difference remained between the 2 groups with regard to the physical QOL domain. A multiple logistic regression analysis found that advanced age, fewer psychiatric admissions, severity of depressive symptoms and use of hypnotics were significant contributors to poor sleep.
Conclusion: Insomnia is independently associated with poor QOL. More attention should be paid in clinical practice to the high rate of insomnia in Chinese schizophrenia patients.