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±11.1years) and 107 healthy controls (males/females=22/85; average age: 41.7±11.9years) 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±11.2years vs. 53.3±11.0years), lower weight (63.7±12.2kg vs. 70.4±15.2kg) and body mass index (BMI) (22.8±4.1kg/m2 vs. 24.2±4.7kg/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.