Patient demographics after Propensity Score matching
| Non-ESPB | ESPB | P value* | SMD† | |
| Sample size (n) | 121 | 121 | ||
| Sociodemographic characteristics | ||||
| Median age (IQR) in years | 63.0 (18.0–83.0) | 64.0 (17.0–84.0) | 0.72 | 0.07 |
| Sex n (%) | ||||
| Male | 60 (49.6) | 60 (49.6) | 1 | <0.001 |
| Female | 61 (50.4) | 61 (50.4) | ||
| Race and ethnicity n (%) | ||||
| Non-Hispanic white | 101 (83.5) | 104 (86.0) | 0.86 | 0.08 |
| Non-Hispanic black | 13 (10.7) | 12 (9.9) | ||
| Other or mixed | 7 (5.8) | 5 (4.1) | ||
| Current smoking n (%) | 12 (9.9) | 11 (9.1) | 1 | 0.03 |
| History of anxiety n (%) | 13 (10.7) | 14 (11.6) | 1 | 0.03 |
| History of depression n (%) | 12 (9.9) | 11 (9.1) | 1 | 0.03 |
| History of chronic pain n (%) | 0 (0.0) | 0 (0.0) | 1 | <0.001 |
| Preoperative opioid use n (%) | 14 (11.6) | 12 (9.9) | 0.84 | 0.05 |
| All | 7 (5.8) | 4 (3.3) | 0.54 | |
| Oxycodone | 5 (4.1) | 9 (7.4) | 0.41 | |
| Tramadol | 1 (0.8) | 2 (1.7) | 0.54 | |
| Hydrocodone | 1 (0.8) | 1 (0.8) | 1 | |
| Hydromorphone | 0 (0.0) | 1 (0.8) | 1 | |
| Buprenorphine | 0 (0.0) | 1 (0.8) | 1 | |
| Oxymorphone | 0 (0.0) | 1 (0.8) | 1 | |
| Morphine | 0 (0.0) | 1 (0.8) | 1 | |
| Codeine | 20.0 (5.0, 60.0) | 20.0 (10.0, 120.0) | 0.39 | |
| Median MED (IQR) in mg | 32 (26.4) | 23 (19.0) | 0.22 | 0.18 |
| Preoperative gabapentin or pregabalin use, n (%) | 12 (9.9) | 11 (9.1) | 1 | 0.03 |
| Surgical characteristics | ||||
| Diagnosis n (%) | ||||
| DDD | 44 (36.4) | 47 (38.8) | 0.79 | 0.05 |
| HNP | 23 (19.0) | 22 (18.2) | 1 | 0.02 |
| Stenosis | 103 (85.1) | 101 (83.5) | 0.86 | 0.05 |
| Spondylolisthesis | 92 (76.0) | 91 (75.2) | 1 | 0.02 |
| Scoliosis | 10 (8.3) | 10 (8.3) | 1 | <0.001 |
| Surgical level n (%) | ||||
| T12–L1 | 0 (0.0) | 1 (0.8) | 1 | 0.13 |
| L1–L2 | 0 (0.0) | 0 (0.0) | 1 | <0.001 |
| L2–L3 | 4 (3.3) | 5 (4.1) | 1 | 0.04 |
| L3–L4 | 24 (19.8) | 23 (19.0) | 1 | 0.02 |
| L4–L5 | 96 (79.3) | 95 (78.5) | 1 | 0.02 |
| L5–S1 | 56 (46.3) | 61 (50.4) | 0.61 | 0.08 |
| Levels fused n (%) | ||||
| 1 level | 78 (64.5) | 75 (62.0) | 0.79 | 0.05 |
| 2 levels | 43 (35.5) | 46 (38.0) | ||
| Levels decompressed n (%) | ||||
| 1 level | 72 (59.5) | 64 (52.9) | 0.57 | 0.18 |
| 2 levles | 41 (33.9) | 51 (42.1) | ||
| 3 levels | 6 (5.0) | 5 (4.1) | ||
| 4 levels | 2 (1.7) | 1 (0.8) | ||
| Median surgical duration (IQR) in mins | 178.0 (66.0–328.0) | 172.0 (49.0–463.0) | 0.91 | 0.12 |
| ASA classification n (%) | ||||
| I | 6 (5.0) | 7 (5.8) | 0.84 | 0.10 |
| II | 105 (86.8) | 107 (88.4) | ||
| III | 10 (8.3) | 7 (5.8) | ||
| Median BMI (IQR) kg/m2 | 28.50 (19.40–43.40) | 27.90 (19.20–42.90) | 0.69 | 0.04 |
*P value compares outcomes in non-erector spinae plane block versus erector spinae plane block; Mann-Whitney 205 U test was used to compare continuous variables and Fisher’s exact tests for categorical variables.
†SMD: the absolute difference of the group means as a percentage of their pooled SD.
ASA, American Society of Anesthesiologists; BMI, body mass index; DDD, degenerative disc disease; ESPB, erector spinae plane block; HNP, herniated nucleus pulposus; L, lumbar vertebral level; MED, morphine equivalent dose; S, sacral level; SMD, standardized mean difference; T, thoracic vertebral level.