Factors associated with decreased bone mineral density in postmenopausal women with schizophrenia

OBJECTIVE This study examined the risk factors for decreased bone mineral density (BMD) in postmenopausal women with schizophrenia. METHODS Cluster sampling method was adopted in this large-sample, cross-sectional study. A total of 219 postmenopausal female inpatients with schizophrenia were selected and interviewed in Beijing. The average age of the patients was 60.4±7.0 years. Clinical assessment instruments included the Positive and Negative Syndrome Scale (PANSS) and a questionnaire with detailed general information and disease-related investigations. Laboratory measurements included prolactin (PRL), estradiol, progesterone, thyroid stimulating hormone, FT3, and FT4. BMD testing was performed by dual-energy X-ray absorptiometry. RESULTS The prevalence of osteoporosis or osteopenia was 66.2% (n=145). Decreased BMD was associated with age, illness duration, therapeutic dose (equivalent chlorpromazine dose), treatment duration, PANSS-negative scores, body mass index (BMI), daily exercises (min/d), drinking (unit/wk), PRL, and estradiol. Multiple logistic regression analysis revealed that age, treatment duration, PANSS-negative score, BMI, and PRL were significantly associated with decreased BMD. CONCLUSION Prevalence of BMD loss was higher in Chinese postmenopausal women with schizophrenia compared to the normal BMD group. A combination of demographic and clinical factors play important roles in determining decreased BMD, including older age, longer treatment duration, more PANSS-negative scores, higher BMI, and higher PRL level.