Table 1.
Demographics and Descriptive Characteristics of Patients Undergoing Instrumented and Noninstrumented Posterior Lumbar Fusions
| Factor or Variable | Unmatched | 4:1 Matched | ||||
| Instrumented Fusion | Noninstrumented Fusion | P Value | Instrumented Fusion | Noninstrumented Fusion | P Value | |
| Total | 117,796 | 5147 | 19,374 | 4850 | ||
| Age ± SD | 62.4 ± 12.0 | 66.7 ± 11.0 | <0.001 | 66.8 ± 10.2 | 66.8 ± 10.3 | 0.975 |
| Sex, n (%) | <0.001 | 0.885 | ||||
| Female | 30,873 (63.4) | 3022 (58.7) | 11,116 (59.2) | 2788 (59.0) | ||
| Male | 17,787 (36.6) | 2125 (41.3) | 7674 (40.8) | 1935 (41.0) | ||
| ECI ± SD | 4.2 ± 3.4 | 4.4 ± 3.4 | <0.001 | 4.2 ± 3.1 | 4.2 ± 3.2 | 0.660 |
| Osteoporosis, n (%) | 1981 (1.7) | 150 (2.9) | <0.001 | 368 (1.9) | 132 (2.7) | <0.001 |
| Insurance, n (%) | <0.001 | 0.009 | ||||
| Commercial | 32,019 (67.8) | 3129 (62.2) | 11,073 (60.7) | 2885 (62.5) | ||
| Medicaid | 1620 (3.4) | 107 (2.1) | 388 (2.1) | 97 (2.1) | ||
| Medicare | 13,586 (28.8) | 1787 (35.6) | 6795 (37.2) | 1632 (35.4) | ||
| Region, n (%) | <0.001 | <0.001 | ||||
| Northeast | 9081 (18.7) | 1250 (22.6) | 3619 (19.3) | 1171 (25.0) | ||
| Midwest | 13,818 (28.5) | 1154 (24.5) | 5243 (28.0) | 1063 (22.7) | ||
| South | 18,512 (38.2) | 2174 (42.5) | 7136 (38.1) | 1979 (42.2) | ||
| West | 7032 (14.5) | 533 (10.4) | 2711 (14.5) | 477 (10.2) | ||
| Surgical specialty, n (%) | <0.001 | <0.001 | ||||
| Neurological | 39,485 (33.5) | 1312 (25.5) | 6401 (33.0) | 1232 (25.4) | ||
| Orthopaedic | 45,176 (38.4) | 2380 (46.2) | 7514 (38.8) | 2258 (46.6) | ||
ECI = Elixhauser comorbidity index
The cohort was matched 4:1 controlling for age, sex, and ECI. Bolded values indicate statistical significance at p < 0.05.