When to refer for surgery in long bone metastases: A powered multivariate analysis of fracture risk and simple algorithm for referral for surgery (the metastatic fracture prediction met FRAP score).

BACKGROUND

It is difficult to predict the risk of pathological fracture in patients with bone metastases. Popular scoring systems like Mirels' may overestimate need for surgery by 20%. The aim was to identify predictors of fracture at 6 months in patients with long bone metastases managed non-surgically.

PATIENTS AND

METHODS

This was an adequately powered retrospective analysis of individuals with a long bone metastasis. Patients were identified from radiology reports and excluded if they had prophylactic surgery or died within 3 months. A literature review and pilot study identified 13 variables of interest. Multivariate analysis was used to generate the metastatic fracture prediction (Met FRAP) score.

RESULTS

From 2009 to 2021 (13 years), 2142 patients with new long bone metastases were identified. 1577 were excluded, leaving a dataset of 565 lesions in 503 patients managed non-surgically. The cohort were 45% female with a mean age of 71 years. Median follow-up in living patients was 2 years (range 1-12 years). The metastatic fracture rate at 1 year was 26%. On multivariate analysis, independent predictors of metastatic fracture included cognitive impairment, metastatic load (p < 0.001 for both), primary cancer type (p < 0.01), radiotherapy, pain requiring opiates and radiographic appearance (p < 0.05 for all). These were used to generate the Met FRAP score. Met FRAP score predicted metastatic fracture at 6 months with 82% accuracy and was more sensitive and specific than Mirels score (61% accuracy, p < 0.001).

DISCUSSION: The Met FRAP score accurately predicts metastatic fracture at 6 months and appears to be more reliable than Mirels score.