Bisphosphonates May Reduce Intraoperative Blood Loss in Surgery for Metastatic Spinal Disease: A Retrospective Cohort Study.

Purpose This study was undertaken to investigate the relationship between bisphosphonate use and intraoperative blood loss following surgery for metastatic spinal disease. Methods We retrospectively analyzed cancer patients who were treated by metastatic spinal tumor surgery at our institution. Recorded data included intraoperative blood loss, timing and duration of bisphosphonate use, and other important confounding factors. We showed the results of crude model, minimally adjusted model, and fully adjusted model to fully observe the effects of bisphosphonates under different adjustment strategies. The timing and duration of bisphosphonate exposure were assessed and statistical results were tested to identify a trend. Results A total of 467 patients were treated by metastatic spinal tumor surgery, with or without bisphosphonate treatments. In all adjustment strategies, intraoperative blood loss was lower in patients using bisphosphonates than in patients without bisphosphonate treatments. In the fully adjusted model, the effect size, confidence interval, and p value were -246.4, -447.0 to -45.8, and 0.017, respectively. In terms of duration, all three models showed the same duration-response relationship: a longer duration of bisphosphonate use accurately predicted a smaller amount of blood loss (p for trend <0.001). We observed an interaction between operative time and bisphosphonate use, the effect size in the bottom tertile group was significantly smaller than that in the other two groups. Conclusion We found that the preoperative use of bisphosphonates could reduce the amount of intraoperative blood loss during metastatic spinal tumor surgery, especially for surgery with longer operative time.