Table 1. Study sample characteristics of patients after lumbar spinal fusion surgery by BMI (kg/m2)a.
| Characteristics | BMI category (kg/m2) | ||||||
|---|---|---|---|---|---|---|---|
| Overall | <25 | 25–30 | 30–35 | 35–40 | 40+ | ||
| Total (N) | 8,049 | 1,890 | 3,122 | 1,983 | 786 | 268 | |
| BMI (kg/m2) | |||||||
| Mean (SD) | 28.9 (5.3) | 22.7 (1.6) | 27.4 (1.4) | 32.1 (1.4) | 37.0 (1.4) | 43.2 (3.6) | |
| Median (IQR) | 28.3 (25.1–32.1) | 23.0 (21.6–24.0) | 27.3 (26.1–28.6) | 32.0 (31.0–33.3) | 36.8 (35.9–38.1) | 42.0 (40.8–44.6) | |
| Age | |||||||
| Mean (SD) | 61.3 (12.8) | 62.7 (14.0) | 61.8 (12.9) | 60.9 (11.7) | 58.7 (11.9) | 56.9 (12.2) | |
| Median (IQR) | 63.0 (53.0–71.0) | 64.0 (55.0–73.0) | 63.0 (54.0–71.0) | 62.0 (53.0–69.0) | 60.0 (51.0–67.0) | 59.0 (50.0–66.0) | |
| Gender, n (%) | |||||||
| Male | 3,421 (42.5) | 636 (33.7) | 1,526 (48.9) | 921 (46.4) | 271 (34.5) | 67 (25.0) | |
| Female | 4,628 (57.5) | 1,254 (66.3) | 1,596 (51.1) | 1,062 (53.6) | 515 (65.5) | 201 (75.0) | |
| Diabetes, n (%) | 1,692 (21.0) | 219 (11.6) | 560 (17.9) | 546 (27.5) | 257 (32.7) | 110 (41.0) | |
| Smoke, n (%) | 776 (9.6) | 214 (11.3) | 308 (9.9) | 157 (7.9) | 64 (8.1) | 33 (12.3) | |
| Admission diagnosis, n (%) | |||||||
| Deformity | 1,003 (12.5) | 252 (13.3) | 395 (12.7) | 243 (12.3) | 90 (11.5) | 23 (8.6) | |
| Degenerative | 5,540 (68.8) | 1,266 (67.0) | 2,192 (70.2) | 1,364 (68.8) | 548 (69.7) | 170 (63.4) | |
| Spondylolisthesis | 1,005 (12.5) | 229 (12.1) | 364 (11.7) | 260 (13.1) | 102 (13.0) | 50 (18.7) | |
| Othersb | 277 (3.4) | 78 (4.1) | 92 (2.9) | 63 (3.2) | 32 (4.1) | 12 (4.5) | |
| Fusion approach, n (%) | |||||||
| Anterior | 845 (10.5) | 237 (12.5) | 339 (10.9) | 172 (8.7) | 75 (9.5) | 22 (8.2) | |
| Combined | 811 (10.1) | 211 (11.2) | 316 (10.1) | 213 (10.7) | 60 (7.6) | 11 (4.1) | |
| Posterior | 6,345 (78.8) | 1,429 (75.6) | 2,440 (78.2) | 1,592 (80.3) | 649 (82.6) | 235 (87.7) | |
a, The sample was grouped into five BMI categories according to the World Health Organization BMI Classification. There were 224 (2.8%) patients missing admission diagnosis and 48 (0.6%) patients missing surgical approach (16); b, other admission diagnoses included neurological dysfunction, pathological (involving neoplasm or osteoporosis), and primary lateral sclerosis. IQR, interquartile range; SD, standard deviation; BMI, body mass index.