Prevalence, risk factors and clinical characteristics of osteoporosis in Chinese inpatients with schizophrenia

Patients with schizophrenia have a high prevalence of developing osteoporosis and osteoporosis-related fractures. We examined the prevalence of osteoporosis and its clinical correlates in Chinese patients with schizophrenia, which is not well-studied. A total of 199 inpatients (males/females = 132/67; average age: 54.5 ± 11.1 years) and 107 healthy controls (males/females = 22/85; average age: 41.7 ± 11.9 years) were recruited. Bone mineral density (BMD) was measured by ultrasonography of the calcaneus. The prevalence of osteoporosis and low BMD (osteoporosis and osteopenia) was 23.1% and 65.3% for the patient group, versus 7.5% and 39.3% for the control group (both p < 0.001). Further, the average BMD T-score in patients was significantly lower than in controls (p < 0.05). There was gender difference in the prevalence of low BMD conditions for the patients (males: 56.1% versus females: 76.1%; p < 0.01) as well as the BMD T-score (p < 0.001). Several risk factors correlated with the osteoporosis classification in the patient group: older age (58.9 ± 11.2 years vs. 53.3 ± 11.0 years), lower weight (63.7 ± 12.2 kg vs. 70.4 ± 15.2 kg) and body mass index (BMI) (22.8 ± 4.1 kg/m2 vs. 24.2 ± 4.7 kg/m2; all p < 0.01) than those without osteoporosis. Stepwise multiple logistic regression analysis indicated that age, weight and BMI remained significantly associated with osteoporosis. In addition, correlation analysis showed significant correlations between BMD T-score and the following parameters: gender, age and drug type (clozapine versus non-clozapine) (Bonferroni corrected p's < 0.05). Our results suggest a higher prevalence of osteoporosis and osteopenia in Chinese schizophrenic inpatients, with both the expected risk factors of gender and age, as well as drug type.