Risk Stratification of Elderly Patients Undergoing Spinal Surgery Using the Modified Frailty Index.

STUDY DESIGN

Retrospective cohort.

OBJECTIVES

To validate the 11-item modified Frailty Index (mFI) as a perioperative risk stratification tool in elderly patients undergoing spine surgery.

METHODS

All consecutive cases of spine surgery in patients aged 65 years or older between July 2016 and June 2018 at a state-wide trauma center were retrospectively reviewed. The primary outcome was post-operative major complication rate (Clavien-Dindo Classification ≥ III). Secondary outcome measures included the rate of all complications, 6-month mortality and surgical site infection.

RESULTS

A total of 348 cases were identified. The major complication rate was significantly lower in patients with an mFI of 0 compared to ≥ 0.45 (18.3% versus 42.5%, = .049). As the mFI increased from 0 to ≥ 0.45 there was a stepwise increase in risk of major complications ( < .001). Additionally, 6-month mortality rate was considerably lower when the mFI was 0 rather than ≥ 0.27 (4.2% versus 20.4%, = .007). Multivariate analysis demonstrated an mFI ≥ 0.27 was significantly associated with an increased incidence of major complication (OR 2.80, 95% CI 1.46-5.35, = .002), all complication (OR 2.93, 95% CI 1.70-15.11, < .001), 6-month mortality (OR 7.39, 95% CI 2.55-21.43, < .001) and surgical site infection (OR 4.43, 95% CI 1.71-11.51, = .002). The American Society of Anesthesiologists' (ASA) index did not share a stepwise relationship with any outcome.

CONCLUSION

The mFI is significantly associated in a gradated fashion with increased morbidity and mortality. Patients with an mFI ≥ 0.27 are at greater risk of major complications, all-complications, 6-monthy mortality, and surgical site infection.