Clinical effect of early bisphosphonate treatment for pyogenic vertebral osteomyelitis with osteoporosis: An analysis by the Cox proportional hazard model

BACKGROUND CONTEXT: Patients with pyogenic vertebral osteomyelitis (PVO) are expected to have an increased risk of bone loss. Therefore, early bisphosphonate therapy would be clinically effective for PVO patients with osteoporosis. PURPOSE: This study aimed to investigate the effect of bisphosphonate on clinical outcomes of PVO patients with osteoporosis. STUDY DESIGN/SETTING: A retrospective comparative study. PATIENT SAMPLE: PVO patients with osteoporosis. OUTCOME MEASURES: Four events of interest for Cox proportional hazard model included surgical treatment, recurrence of infection, subsequent fracture of adjacent vertebral bodies, and death. METHODS: PVO patients were divided into three groups: group A (initiation of bisphosphonate within 6 weeks after PVO diagnosis), group B (initiation of bisphosphonate between 6 weeks and 3 months after PVO diagnosis), and group C (no treatment for osteoporosis). Cox proportional hazard model was used for the four events of interest. RESULTS: A total of 360 PVO patients with osteoporosis were investigated for the four events of interest. Group A had significantly lower hazard ratios for undergoing later (>6 weeks after diagnosis) surgery than group C (p = .014) despite similar occurrences of overall surgery. A significant difference was also observed in the occurrence of subsequent fractures at adjacent vertebral bodies (p = .001 for model 1 and p = .002 for model 2). Groups A and B had significantly lower hazard ratios for subsequent fracture than group C. No significant differences were observed in the hazard ratios of recurrence and death among the three groups. CONCLUSIONS: Early bisphosphonate treatment in PVO patients with osteoporosis was associated with a significantly lower occurrence of subsequent vertebral fracture at adjacent vertebral bodies and lower occurrence of subsequent surgery. (C) 2018 Elsevier Inc. All rights reserved.