Comparison of 90-d medical complications of patients with an ECI score of 1 to 5 undergoing primary 1- to 2-level lumbar fusion in the Medicare database.
| Comparison | Control Group, % | Study Group, % | OR | 95% CI | P Value |
| ECI 1 vs ECI 2 | 2.45% | 2.85% | 1.17 | 1.05–1.30 | 0.003 |
| ECI 1 vs ECI 3 | 2.45% | 2.98% | 1.22 | 1.10–1.36 | <0.001 |
| ECI 1 vs ECI 4 | 2.45% | 3.10% | 1.26 | 1.13–1.40 | <0.001 |
| ECI 1 vs ECI 5 | 2.45% | 2.89% | 1.18 | 1.06–1.31 | 0.001 |
| Total | 9.80% | 11.82% | 1.22 | 1.16–1.30 | <0.001 |
Abbreviation: ECI, Elixhauser Comorbidity Index.