Table 5.
Demographics and Outcomes Associated With Psoas Muscle Indices (PMI) at L3 and L4.
| PMI at L3 | PMI at L4 | |||||
|---|---|---|---|---|---|---|
| Variable | Quartile 4 | Quartiles 1–3 | P value | Quartile 4 | Quartiles 1–3 | P-value |
| Age (years) | 70.7 (8.0) | 69.2 (8.0) | .22 | 69.2 (9.6) | 69.7 (7.4) | .72 |
| Gender (% female; n) | 91.4% (53) | 57.4% (101) | <.001* | 89.8% (53) | 58.0% (102) | <.001* |
| BMI (Kg/m2) | 26.1 (6.2) | 28.8 (6.0) | .003* | 25.7 (5.3) | 29.0 (6.2) | <.001* |
| Index surgery Revision surgery |
79.3% (46) 20.7% (12) |
74.4% (131) 25.6% (45) |
.45 | 76.3% (45) 23.7% (14) |
75.0% (132) 25.0% (44) |
.85 |
| Pelvic fixation (%) | 87.9% (51) | 94.3% (166) | .10 | 89.8% (53) | 93.2% (164) | .40 |
| Levels of fusion | 9.8 (3.2) | 9.1 (2.6) | [.10] | 9.4 (2.7) | 9.2 (2.7) | .62 |
| Cobb angle (°) | 26.8 (12.9) | 25.2 (13.1) | .42 | 25.8 (12.1) | 25.4 (2.7) | .82 |
| SVA (cm) | 7.0 (4.6) | 5.9 (4.7) | .17 | 6.1 (4.9) | 6.2 (4.6) | .92 |
| Cobb LL (°) | 36.7 (16.2) | 37.6 (18.0) | .74 | 39.6 (16.2) | 36.7 (17.9) | .27 |
| SS (°) | 29.1 (10.1) | 29.3 (10.8) | .91 | 29.4 (10.2) | 29.2 (10.7) | .93 |
| PT (°) | 23.6 (9.7) | 23.7 (9.6) | .97 | 22.1 (9.6) | 24.2 (9.5) | .16 |
| PI (°) | 49.9 (12.7) | 50.0 (12.7) | .98 | 48.4 (13.8) | 40.6 (12.3) | .28 |
| Smoking status | ||||||
| Current Former Never |
8.6% (5) 37.9% (22) 53.4% (31) |
2.3% (4) 40.9% (72) 56.9% (100) |
.17 | 8.5% (5) 30.5% (18) 61.0% (36) |
2.4% (4) 43.8% (77) 54.0% (95) |
.07 |
| Alcohol use (% current) | 46.6% (27) | 46.6% (81) | >.99 | 49.2% (29) | 45.4% (79) | .62 |
| ASA score | 2.6 (.5) | 2.6 (.6) | .93 | 2.6 (.5) | 2.6 (.6) | .87 |
| Anesthesia duration (mins) | 292.6 (82.7) | 293.2 (67.8) | .95 | 284.2 (69.6) | 295.4 (72.5) | .30 |
| EBL (mL) | 1435.8 (981) | 1645.4 (977) | .16 | 1372 (949) | 1664 (980) | .047* |
| Intraoperative RBC transfusion (mL) | 1035.1 (1005) | 1043.2 (1075) | .96 | 1014 (1105) | 1046 (1040) | .84 |
| Intraoperative total transfusion (mL) | 1456.6 (1542) | 1385.5 (1630) | .77 | 1406 (1686) | 1395 (1581) | .97 |
| Intraoperative albumin transfusion (mL) | 952.6 (653) | 1110.8 (622) | .10 | 1000 (625) | 1098 (634) | .30 |
| Preoperative hemoglobin (g/dL) | 12.9 (1.4) | 13.3 (1.6) | .10 | 12.9 (1.3) | 13.3 (1.6) | .11 |
| ICU LOS (hrs) | 39.6 (28.0) | 41.9 (43.6) | .70 | 39.4 (28.2) | 42.0 (43.5) | .67 |
| Hospital LOS (days) | 5.9 (2.6) | 6.4 (3.5) | .39 | 6.1 (2.8) | 6.3 (3.4) | .59 |
| POD walking (days) | 2.6 (3.0) | 2.0 (1.8) | .084 | 2.4 (3.0) | 2.1 (1.9) | .41 |
| Postoperative RBC transfusions (mL) | 698.9 (851) | 598.1 (565) | [.40] | 758.6 (802) | 574.1 (581) | .06 |
| Postoperative total transfusion volume (mL) | 896.7 (1192) | 733.5 (780) | .23 | 980.5 (1174) | 700.3 (777) | [.09] |
| Postoperative hemoglobin (g/dL) | 9.7 (1.7) | 10.0 (1.5) | .17 | 9.6 (1.6) | 10.0 (1.5) | .052 |
| Hemoglobin drop (%) | 12.1% (1.4%) | 12.5% (1.4%) | .13 | 12.1 (1.3) | 12.5 (1.7) | .15 |
| Discharge disposition (% home) | 32.8% (19) | 36.0% (63) | .45 | 35.6% (21) | 35.4% (62) | .72 |
| 7-day readmission | 1.7% (1) | 2.3% (4) | >.99 | 1.7% (1) | 2.3% (4) | .79 |
| 30-day readmission | 10.3% (6) | 7.4% (13) | .47 | 8.5% (5) | 8.0% (14) | .90 |
| 90-day readmission | 15.5% (9) | 15.3% (27) | .97 | 13.6% (8) | 15.9% (28) | .67 |
| Need for revision surgery (%) | 41.4% (24) | 33.0% (58) | .24 | 33.9% (20) | 35.2% (62) | .85 |
| ODI change | −12.0 (15.4) | −9.8 (17.1) | .45 | −12.7 (16.3) | −9.8 (17.0) | .34 |
P-values in brackets represent non-parametric data analyzed with Welch’s t-test (*= P < .05). Abbreviations: psoas muscle index (PMI), Oswestry Disability Index (ODI), sagittal vertical axis (SVA), Cobb lumbar lordosis (LL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), and length of stay (LOS).