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 both demographic variables and limited to the same operating surgeon.
| Variable | Least Overlap (N = 34) | Most Overlap (N = 34) | P Value |
| Age (y), mean (range) | 56.74 (24–76) | 58.26 (26–76) | 0.64 |
| Gender, n (%) | >0.99 | ||
| Male | 19 (55.9%) | 19 (55.9%) | |
| Female | 15 (44.1%) | 15 (44.1%) | |
| Race, n (%) | >0.99 | ||
| Black | 1 (2.9%) | 1 (2.9%) | |
| White | 33 (97.1%) | 33 (97.1%) | |
| Insurance, n (%) | 0.20 | ||
| Commercial | 4 (11.8%) | 0 (0%) | |
| Medicare | 12 (35.3%) | 13 (38.2%) | |
| Medicaid | 2 (5.9%) | 1 (2.9%) | |
| Managed care | 11 (32.4%) | 10 (29.4%) | |
| Blue cross | 5 (14.7%) | 10 (29.4%) | |
| Tobacco use within past 12 mo, n (%) | >0.99 | ||
| Yes | 1 (2.9%) | 1 (2.9%) | |
| No | 33 (97.1%) | 33 (97.1%) | |
| Fasting blood glucose (mg/dL), mean (range) | 122.48 (92–174) | 128.73 (79–207) | 0.46 |
| Surgeries before index operation (count), mean (range) | |||
| Ever | 0.44 (0–10) | 0.24 (0–4) | 0.98 |
| 90 d Prior | 0.06 (0–2) | 0.03 (0–1) | >0.99 |
| Direct cost of operative supplies and implants ($), mean (range) | 7120 (116–26,035) | 6400 (342–17,459) | 0.75 |
| Length of hospital stay (h), mean (range) | 86.73 (25–242) | 69.65 (31–151) | 0.10 |
| Length of follow-up (mo), mean (range) | 34.84 (3.0–78.44) | 41.42 (1.3–77.69) | 0.21 |
| Non-neurosurgical operations 30 d after index operation (count), mean (range) | 0.12 (0–1) | 0.09 (0–1) | 0.70 |