Table 1.
Baseline Characteristics and Demographics
| ACF (N=45,629) | PCF (N=14,439) | P-value | |
|---|---|---|---|
|
|
|||
| Age (year) ± SD | 57.6±12.1 | 62.6±12.0 | <0.001* |
| Admission Type | |||
| Elective | 77.00% | 71.80% | <0.001* |
| Emergent | 5.75% | 9.52% | <0.001* |
| Urgent Care | 6.87% | 7.89% | <0.001* |
| Weekend Admission | 2.58% | 4.06% | <0.001* |
| Elixhauser Index Score ± SD | 1.4±1.4 | 2.0±1.6 | <0.001* |
| Female | 46.70% | 39.90% | <0.001* |
| Hospital Sizeize | |||
| Small | 10.90% | 8.40% | <0.001* |
| Medium | 21.90% | 18.00% | <0.001* |
| Large | 66.80% | 73.00% | <0.001* |
| Hospital Region | |||
| Northeast | 12.70% | 19.70% | <0.001* |
| Midwest | 19.80% | 21.40% | <0.001* |
| South | 47.30% | 39.70% | <0.001* |
| East | 20.20% | 19.20% | <0.05 |
| Teaching Hospital | 55.60% | 71.20% | <0.001* |
| Primary Payment Method | |||
| Medicare | 34.50% | 50.00% | <0.001* |
| Medicaid | 5.90% | 6.80% | <0.001* |
| Private Insurance | 50.70% | 35.90% | <0.001* |
| Self-Payment | 1.70% | 1.90% | 0.08 |
| No-Charge | 0.18% | 0.30% | 0.07 |
| Other | 7.00% | 5.00% | <0.001* |
| Race | |||
| Asian | 1.20% | 1.50% | <0.01 |
| Black | 9.80% | 12.50% | <0.001* |
| Hispanic | 3.80% | 4.90% | <0.001* |
| White | 62.10% | 59.90% | <0.001* |
| Native American | 0.37% | 0.40% | 0.621 |
| Other | 1.60% | 2.00% | <0.001* |
| Comorbidity | |||
| AIDS | 0.7% | 0.13% | <0.05 |
| Alcohol Use | 1.80% | 3.10% | <0.001* |
| Arthritis | 2.70% | 5.60% | <0.001* |
| Congestive Heart Failure | 2.10% | 4.00% | <0.001* |
| Chronic Lung Disease | 15.50% | 18.30% | <0.001* |
| Depression | 9.80% | 11.10% | <0.001* |
| Diabetes Mellitus | 15.10% | 17.90% | <0.001* |
| Hypertension | 46.10% | 57.50% | <0.001* |
| Obese | 7.70% | 8.00% | 0.32 |
| Liver Disease | 1.00% | 1.80% | <0.001* |
| Multi-Level Fusion (4–8 levels) | 13.60% | 12.80% | <0.10 |
| Kyphosis | 2.10% | 5.90% | <0.001* |
| Lordosis | 0.20% | 0.50% | <0.001* |
| Median Income in Zip Code (quartile) | |||
| 1st | 19.40% | 21.90% | <0.001* |
| 2nd | 24.70% | 23.80% | <0.05 |
| 3rd | 25.90% | 25.30% | 0.139 |
| 4th | 27.40% | 26.30% | <0.05 |
denotes statistically significantly different result
All data come from the NIS. All patients with a diagnosis of CSM between 1998–2011 and that were 18 years or older at the time of admission were included. The Elixhauser Index is a composition of thirty comorbidities characterizing significant conditions associated with in-hospital mortality, including acute and chronic comorbidities. The Elixhauser index allows for standardized risk adjustment in administrative databases such as the NIS. The Elixhauser Index Score ranges from zero to thirty, with zero indicating that a patient has none of the thirty comorbidities and thirty indicating that a patient has all thirty of the comorbidities. An alpha-level of 0.001 was used to determine significance. All calculations were performed using Stata 13.0.