Background. Metastatic bone patients who require surgery needs to be evaluated in order to maximise quality of life and avoiding functional impairment, minimising the risks connected to the surgical procedures. The best surgical procedure needs to be tailored on survival estimation. There are no current available tool or method to evaluate survival estimation with accuracy in patients with bone metastasis. We recently developed a clinical decision support tool, capable of estimating the likelihood of survival at 3 and 12 months following surgery for patients with operable skeletal metastases. After making it publicly available on . www.PATHFx.org. , we attempted to externally validate it using independent, international data. Methods. We collected data from patients treated at 13 Italian orthopaedic oncology referral centers between 2008 and 2012, then applied to PATHFx, which generated a probability of survival at three and 12-months for each patient. We assessed accuracy using the area under the receiver-operating characteristic curve (AUC), clinical utility using Decision Curve Analysis DCA), and compared the Italian patient data to the training set (United States) and first external validation set (Scandinavia). Results. The Italian dataset contained 287 records with at least 12 months follow-up information. The AUCs for the three-month and 12-month estimates was 0.80 and 0.77, respectively. There were missing data, including the surgeon's estimate of survival that was missing in the majority of records. Physiologically, Italian patients were similar to patients in the training and first validation sets. However notable differences were observed in the proportion of those surviving three and 12-months, suggesting differences in referral patterns and perhaps indications for surgery. Conclusions. PATHFx was successfully validated in an Italian dataset containing missing data. This study demonstrates its broad applicability to European patients, even in centers with differing treatment philosophies from those previously studied

Background. Metastatic bone patients who require surgery needs to be evaluated in order to maximise quality of life and avoiding functional impairment, minimising the risks connected to the surgical procedures. The best surgical procedure needs to be tailored on survival estimation. There are no current available tool or method to evaluate survival estimation with accuracy in patients with bone metastasis. We recently developed a clinical decision support tool, capable of estimating the likelihood of survival at 3 and 12 months following surgery for patients with operable skeletal metastases. After making it publicly available on . www.PATHFx.org. , we attempted to externally validate it using independent, international data. Methods. We collected data from patients treated at 13 Italian orthopaedic oncology referral centers between 2008 and 2012, then applied to PATHFx, which generated a probability of survival at three and 12-months for each patient. We assessed accuracy using the area under the receiver-operating characteristic curve (AUC), clinical utility using Decision Curve Analysis DCA), and compared the Italian patient data to the training set (United States) and first external validation set (Scandinavia). Results. The Italian dataset contained 287 records with at least 12 months follow-up information. The AUCs for the three-month and 12-month estimates was 0.80 and 0.77, respectively. There were missing data, including the surgeon's estimate of survival that was missing in the majority of records. Physiologically, Italian patients were similar to patients in the training and first validation sets. However notable differences were observed in the proportion of those surviving three and 12-months, suggesting differences in referral patterns and perhaps indications for surgery. Conclusions. PATHFx was successfully validated in an Italian dataset containing missing data. This study demonstrates its broad applicability to European patients, even in centers with differing treatment philosophies from those previously studied. Level of Evidence. IV. None of the authors have financial disclosures or conflicts of interest to declare. The study presented did not need the approval by ethics committee