Evidence for the use of preoperative risk assessment scores in elective cranial neurosurgery: A systematic review of the literature

BACKGROUND:: Preoperative risk scores are designed to guide patient management by providing a means of predicting operative outcome. Several risk scores are used in neurosurgery, but studies on their clinical relevance are scarce. Therefore, it is not clear whether these risk scores are beneficial or helpful in predicting outcome after elective cranial neurosurgery. In this review, we summarize the current scientific evidence for using preoperative risk scores in elective cranial neurosurgery. METHODS:: A systematic review of the MEDLINE, Embase, and PubMed databases in November 2013 yielded 25 relevant studies with a minimum of 30 patients per study. The studies evaluated the value of the preoperative ASA physical status classification, the Karnofsky performance score (KPS), the Charlson comorbidity score, the modified Rankin Scale and the sex, KPS, ASA physical status classification, location, and edema (SKALE) score in assessing postoperative outcome in cranial neurosurgery. Surgery-related and nonsurgical complications were assessed separately whenever reported in the original article. For this purpose, the studies were placed into 4 categories based on the reported outcome: surgery-related outcome, nonsurgical outcome, morbidity, and mortality. The Preferred Reporting Items for Systematic reviews and Meta-analyses guidelines for systematic reviews were followed. RESULTS:: KPS has the strongest support in the literature for predicting surgery-related outcomes. There is no strong support in the literature for the use of any preoperative scores in predicting nonsurgical outcomes after elective craniotomies. KPS and ASA physical status classification seem to predict early (≤ 30-day) morbidity of intracranial tumor patients. The Charlson comorbidity score may be applicable in predicting mortality of elective intracranial aneurysm patients. Only 4 studies were prospective in design. CONCLUSIONS:: Large prospective studies are needed to validate the use of the reviewed risk scores in elective cranial neurosurgery. It appears, however, that the patient's preoperative physical and functional status can be used to predict the short-and long-term outcome in elective cranial neurosurgery.