Disparities Attributable to Sex Differences in 4680 Lumbar Fusion Outcomes

While studies have examined the relationship between sex and outcomes after lumbar fusion surgery, few have strictly controlled for other patient-level variables. In this study, we use coarsened exact matching (CEM) to determine the effect of patient-reported sex on spinal fusion outcomes.

Outcomes across 4680 consecutive adult single-level, posterior-only lumbar fusions at a multihospital academic medical center were retrospectively assessed. First, univariate analyses were performed to broadly examine the effect of sex on surgical outcomes, uncontrolled for other patient factors. Next, the population was split by sex (male vs. female) and matched 1:1 on demographic and medical factors known to influence outcomes (including age, race, smoking status, and past surgical history) using CEM. CEM effectively controls for confounding variable bias by creating pairs of matched samples and preserving the fidelity of each covariate through binning. Primary outcomes included 30-day and 90-day readmissions, emergency department visits, reoperations, and mortality. Secondary outcomes included discharge disposition and length of hospital stay.

Between otherwise exactly matched male-female pairs, females were less likely to be discharged home (odds ratio 1.70, P < 0.001) and had a longer length of stay (mean: 95.7 vs. 87 hours, P < 0.001). No differences in readmissions or reoperations were observed between matched cohorts.

Female patients encountered longer hospital stays and higher odds of nonhome discharge after single-level lumbar fusion compared to otherwise exactly matched male patients.