Posterior Lumbar Fusion Is Being Performed for Patients of Increasing Comorbidity Burden Over the Years, but Adverse Events Are Not Going Up.

introductionComorbidity indices, such as the Elixhauser Comorbidity Index (ECI), are increasingly used to track comorbidities, but annual trends and association with adverse outcomes following posterior lumbar fusion (PLF) have not been well characterized.

methodsPatients who underwent single-level PLF ± interbody fusion were identified from the 2010 to 2022 PearlDiver M165 administrative database and stratified into ECI cohorts that correlated with any, minor, and severe adverse events (AAE, MAE, SAE). ECI trends were tracked over the years and associated 90-day adverse events determined. Odds of such adverse events were analyzed using multivariate logistic regression controlling for age and sex. Linear regression was used to describe this association.

resultsThe median ECI of patients who underwent PLF in 2010 was 1 (inner quartile range [IQR]: 0-2) versus 2022 when it was 5 (IQR: three-8) (P < 0.001). Despite this increase in ECI over the years, the incidence of adverse events did not increase in 2022 vs 2010: AAE (10.1% vs 11.1%, P = 0.005), MAE (7.5% vs 7.9%, P = 0.197), and SAE (4.6% vs 4.8%, P = 0.392). The increase in odds ratio (OR) of AAEs increased with ECI gradually up to ECI 5 to 6 (slope = 0.49, R2 = 0.96) but then steeper after ECI 5 to 6 (slope = 1.41, R2 = 0.96). DISCUSSION: Despite a year-to-year increase in ECI among PLF patients, the incidence of adverse events has not mirrored this trend, likely reflecting improvements in perioperative management and preoperative patient optimization over time.