Characteristics of the subset of patients with the least amount of overlap (bottom 40% of patients with overlap) and the most amount of overlap (top 10% of patients with overlap), subsequently matched on demographic variables but not the operating surgeon.
| Variable | Least Overlap (N = 79) | Most Overlap (N = 79) | P Value |
| Age (y), mean (range) | 61.96 (24–79) | 63.20 (26–79) | 0.50 |
| Gender, n (%) | >0.99 | ||
| Male | 32 (40.5%) | 32 (40.5%) | |
| Female | 47 (59.5%) | 47 (59.5%) | |
| Race, n (%) | >0.99 | ||
| Black | 2 (2.5%) | 2 (2.5%) | |
| White | 77 (97.5%) | 77 (97.5%) | |
| Insurance, n (%) | 0.53 | ||
| Commercial | 3 (3.8%) | 1 (1.3%) | |
| Medicare | 39 (49.4%) | 42 (53.2%) | |
| Medicaid | 4 (5.1%) | 1 (1.3%) | |
| Managed care | 22 (27.8%) | 21 (26.6%) | |
| Blue cross | 11 (13.9%) | 14 (17.7%) | |
| Tobacco use within past 12 mo, n (%) | >0.99 | ||
| Yes | 1 (1.3%) | 1 (1.3%) | |
| No | 78 (98.7%) | 78 (98.7%) | |
| Fasting blood glucose (mg/dL), mean (range) | 136.26 (92–222) | 128.48 (79–207) | 0.35 |
| Surgeries before index operation (count), mean (range) | |||
| Ever | 0.19 (0–4) | 0.14 (0–4) | 0.98 |
| 90 d Prior | 0.03 (0–2) | 0.01 (0–1) | >0.99 |
| Direct cost of operative supplies and implants ($), mean (range) | 10,606 (960–42,850) | 6029 (342–20,689) | <0.001 |
| Length of hospital stay (h), mean (range) | 106.43 (48–400) | 84.92 (26–367) | 0.001 |
| Length of follow-up (mo), mean (range) | 43.36 (3.75–81.27) | 40.16 (0.66–80.75) | 0.41 |
| Non-neurosurgical operations 30 d after index operation (count), mean (range) | 0.04 (0–1) | 0.08 (0–1) | 0.31 |
Note: Statistically significant (P < 0.05) values are bolded.