Frailty versus neurologic severity as predictors of perioperative outcomes among patients undergoing surgery for degenerative cervical myelopathy.

BACKGROUND: Degenerative cervical myelopathy (DCM) is a common cause of spinal cord dysfunction. Frailty metrics such as the five-item modified Frailty Index (mFI-5) are increasingly used for risk stratification, so we investigated whether frailty independently predicts outcomes after accounting for underlying neurological impairment as measured by the modified Japanese Orthopaedic Association (mJOA) score. METHODS: In this retrospective cohort study, we identified adults presenting with DCM who underwent surgical treatment at an academic center (2016-2020). Our exposures were frailty (mFI-5: non-frail 0, pre-frail 1, or frail ≥ 2) and DCM severity (mJOA: mild ≥ 15, moderate 12-14, severe ≤ 11). Outcomes included discharge to home versus rehabilitation, hospital length of stay (LOS), and cost of admission. Risk-adjusted multivariable regression models were constructed, followed by 1:1 propensity score matching on frailty and DCM severity. RESULTS: A total of 487 patients were included. Frailty was correlated with DCM severity (Spearman ρ = -0.33, P < 0.001). On univariable analysis, greater mFI-5 and more severe mJOA scores were associated with lower rates of home discharge, longer LOS, and higher costs (all P < 0.001). However, in multivariable models, moderate and severe DCM independently predicted lower odds of home discharge (OR, 0.10-0.12, both P < 0.001), while mFI-5 was not independently associated. In matched analyses, mJOA severity remained associated with discharge disposition, whereas mFI-5 was not. CONCLUSIONS: Among surgically treated patients with DCM, after accounting for DCM disease severity, frailty does not independently predict postoperative discharge disposition. These findings suggest that mJOA-based impairment may be a more relevant determinant of perioperative outcomes than frailty and should be prioritized in risk stratification.