The Economics of Surgical Decision-Making in Geriatric Type II Odontoid Fractures: Reframing the Role of Frailty

Type II odontoid fractures are among the most common cervical fractures in older adults and are increasing in incidence, yet management remains controversial. Operative fixation may offer earlier reduction in pain and disability but is associated with higher costs and greater morbidity in older and frail patients. We sought to perform a cost-utility analysis of operative vs nonoperative care of type II odontoid fractures in older adults, assessing the impact of age and frailty.

A lifetime, time-homogeneous Markov model compared operative and nonoperative strategies in patients 65 years or older. Costs (2022 USD) were derived from the US Nationwide Inpatient Sample (2016-2022) and health utilities from Short Form-6 dimension scores in the AO Spine North America geriatric odontoid fracture cohort to estimate quality-adjusted life years (QALYs). Transition probabilities were obtained from a systematic review. Analyses were performed from a healthcare payer perspective to calculate the incremental cost-utility ratio (ICUR). We applied a $100 000/QALY willingness-to-pay threshold to determine cost-effectiveness. Sensitivity analyses assessed robustness. Frailty effects on costs and utilities were modeled with regressions adjusting for the modified frailty index-5 (mFI-5) and incorporated into the model.

In the base case of an 81-year-old patient, nonoperative care yielded 4.09 QALYs at $15 840 vs 4.28 QALYs at $40 246 for surgery (ICUR $131 324/QALY). One-way sensitivity analysis demonstrated that operative management was cost-effective below ∼77 years. Incorporating frailty-adjusted costs and utilities shifted this threshold downward to ∼76 years for mFI-5 = 0 and ∼69 for mFI-5 = 5. Probabilistic microsimulations incorporating parameter uncertainty demonstrated robustness of findings in which ICURs rose with both age and frailty.

In this contemporary cost-utility analysis, both age and frailty were key determinants of surgical value. Increasing frailty lowered the age threshold for cost-effective surgery. Incorporating frailty assessment may improve value-conscious surgical decision-making in geriatric odontoid fractures.