Accumulating deficits model of frailty and postoperative mortality and morbidity: its application to a national database.

BACKGROUND: Frailty has been associated with a number of adverse outcomes. One model of frailty is the "accumulating deficits" concept. We hypothesized that this model can be applied to a national database to predict postoperative mortality and morbidity.
METHODS: We accessed the National Surgical Quality Improvement Program (NSQIP) Participant Use File for the years 2005-2009 for inpatient surgical patients who had undergone cardiac, general, gynecologic, neurosurgical, orthopedic, otolaryngologic, plastic, general thoracic, urologic, and vascular surgical operations. Items of the Canadian Study of Health and Aging-frailty index (FI) were compared with preoperative clinical variables recorded by NSQIP. Eleven items were matched, and a simplified FI, defined as the number of deficits present divided by the number of deficits matched, using the number of items present was determined for each patient. The 30-d morbidity and mortality were correlated to this simplified FI and stratified by operation complexity based on the operation's relative value units.
RESULTS: Of the 971,434 patients identified, there was a stepwise increase in risk of both mortality (odds ratios ranged from 1.33 to 46.33) and morbidity (odds ratios ranged from 1.24 to 3.36) for each unit increase in FI for each specialty and each level of operation complexity (trend of odds P value <0.0001 for all comparisons).
CONCLUSIONS: A simple 11-point FI correlated with both mortality and morbidity for all surgical specialties. This may be applicable to other national databases and clinical practice.