Demographics and baseline characteristics
| Preintervention (n=45) | Postintervention (n=38) | P value | |
| Median age (IQR) in years | 67 (61–70) | 66 (61–72) | 0.50* |
| Male, n (%) | 44 (99) | 38 (100) | >0.99† |
| Female, n (%) | 1 (1) | 0 (0) | >0.99† |
| Mean height (SD) in cm | 177 (8) | 178 (14) | 0.97‡ |
| Mean weight (SD) in kg | 92 (17) | 88 (16) | 0.34‡ |
| Mean body mass index (SD) in kg/m² | 29 (5) | 28 (5) | 0.44‡ |
| Median ASA physical status (IQR) | 3 (2–3) | 3 (2–3) | 0.30* |
| Psychiatric comorbidity, n (%) | 24 (53) | 23 (60) | 0.51§ |
| Substance abuse disorder, n (%) | 21 (47) | 15 (39) | 0.51§ |
| Prescribed preoperative opioids, n (%) | 16 (36) | 9 (24) | 0.24§ |
| Instrumented fusion cases, n (%) | 9 (20) | 10 (26) | 0.50§ |
*Mann-Whitney U test.
†Fisher’s exact test.
‡Student’s t-test.
§χ2 test.
ASA, American Society of Anesthesiologists.