Increasing Patient Complexity Is Associated With Longer In-Hospital Lengths of Stay and Higher Rates of Medical Complications Following Primary 1- to 2-Level Lumbar Fusion

Background The Elixhauser Comorbidity Index (ECI) is a stratification tool to predict adverse surgical outcomes. No studies have explored the relationship between ECI and outcomes following primary 1- to 2-level lumbar fusion (1-2LF). The purpose was to determine whether an ECI score greater than 1 correlated with (1) longer in-hospital length of stay (LOS) and (2) greater odds of developing 90-day medical complications. Methods A retrospective review from 2004 to 2015 was performed using the Medicare Standard Analytical Files for patients undergoing primary LF. Patients with ECI scores from 2 to 5 served as the study cohorts (1 for each ECI score), and patients with an ECI score of 1 served as the control cohort. In-hospital LOS and 90-day medical complications were compared between cohorts. A P value of <0.001 was statistically significant. Results A total of 105,120 patients were equally distributed between the 5 cohorts. Patients with an ECI score of 2 (6.00 ± 4.51), ECI 3 (6.22 ± 4.67), ECI 4 (7.35 ± 5.05), or ECI 5 (8.99 ± 5.67) had longer in-hospital LOS compared with patients with an ECI score of 1 (4.28 ± 4.36) (all P < 0.001). Patients with an ECI score of 2 (OR: 1.17, 95% CI: 1.05–1.30, P = 0.003; 2.85% vs 2.45%), ECI 3 (OR: 1.22, 95% CI: 1.10–1.36, P < 0.001; 2.98% vs 2.45%), ECI 4 (OR: 1.26, 95% CI: 1.13–1.40, P < 0.001; 3.10% vs 2.45%), or ECI 5 (OR: 1.18, 95% CI: 1.06–1.31, P = 0.001; 2.89% vs 2.45%) had greater incidence and odds of 90-day medical complications such as pneumonia, deep vein thrombosis, cerebrovascular accidents, and myocardial infarctions than patients in the control group (all P < 0.0001). Conclusions Increasing ECI score was associated with longer in-hospital LOS and increased 90-day medical complication rates following 1-2LF. This study is the first to establish a correlation between ECI score, in-hospital LOS, and complication rates following lumbar fusion. Clinical Relevance ECI score may assist physicians in adjusting pre- and postoperative care for complex patients undergoing 1-2LF. Level of Evidence 3.