Objective: To determine the prevalence of low bone mineral density in schizophrenia patients treated with prolactin (PRL)-elevating antipsychotics (APD) and to identify factors influencing bone density.
Design: This was a 1-day prevalence trial to estimate rates of antipsychotic-induced hyperprolactinemia and associated morbidity. The primary analysis of this study, which was the prevalence of hyperprolactinemia, has been presented previously.
Methods: Patients with schizophrenia (N=402), who had been treated in the community with conventional APD or risperidone for at least 3 months were included. Patients excluded were those taking PRL-sparing antipsychotics, and/or concomitant medications known to elevate PRL. Bone density (T-score) was determined by ultrasonography of the calcaneus. Bone metabolism was assessed by serum levels of osteocalcin (OCN). Regression analysis was used to determine the effect of age, length of APD treatment, and PRL on T-scores and OCN for both males and females, respectively.
Results: The frequency of low bone mass (T-scores =/<-1) was 23.2% in females and 31.0% in males. Decreased T-scores were significantly associated with increased age for both males (p=.007) and females (p=.0001). Length of APD treatment was not significantly associated with T-scores, when controlling for age in either gender. In addition to age, decreased T-scores were also significantly associated with increased PRL in males (p=.05), but not in females. Increased OCN was significantly associated with increased PRL in both females (p=.03) and males (p=.05) with increased age (p<.01) in females but younger age (p<.01) in males. Increased OCN was consistent with decreased T-scores.
Conclusions: Decreased bone mineral density was highly prevalent in a chronic psychiatric population treated with PRL-elevating APDs. Identified risk factors appear to be increased age, as well as increased PRL for both females and males. Bone demineralization may be a common comorbidity in psychiatric patients treated with PRL-elevating APDs.
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