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.