Frailty indices in patients undergoing surgical resection of brain metastases: a systematic review.

Brain metastases are a relatively common occurrence in patients with primary malignancies, with an incidence ranging from 9 to 17%. Their prevalence has increased due to treatment advancements that have led to improved survival in cancer patients. Frailty has demonstrated the ability to outperform greater patient age in surgical decision-making by predicting postoperative adverse events that include mortality, extended length of hospital stay, non-routine discharge disposition, and postoperative complications. Although predictive models based on frailty have been increasingly utilized in literature, their generalizability remains questionable due to inadequacies in model development and validation. Our systematic review describes development and validation cohorts of frailty indices used in patients undergoing surgical resection of brain metastases and serves as a guide to their incorporation in the outpatient clinical setting. A systematic review of literature was performed using PubMed and Google Scholar. Articles that reported outcomes using frailty indices in patients undergoing surgical resection of brain metastases were included. The Newcastle Ottawa Scale (NOS) was used to assess for risk of bias across individual studies. Studies with NOS > 5 were considered high quality. We identified 238 articles through our search strategy. After a title and abstract screen, followed by a full text review, 9 articles met criteria for inclusion. The 5- and 11-factor modified frailty indices were most frequently utilized (n = 4). Five studies utilized single-hospital databases, and four utilized nationwide databases. Six studies were considered high-quality based on the NOS. Although frailty indices have demonstrated the ability to predict outcomes in patients undergoing surgical resection of brain metastases, further validation of these indices is necessary prior to their incorporation in clinical practice.