Table 4.
Bivariate analysis of potential predictors and test of significance
| No. | Length of stay (days) | Operative time (min) | Outpatient surgical visits (no.) | Time spent per patient (min) | |
|---|---|---|---|---|---|
| Median (P5–P95) | Median (P5–P95) | Median (P5–P95) | Median (P5-P95) | ||
| Age | |||||
| <61 | 113 | 4 (1–9)* | 105 (54–182) | 5 (3–11) | 300 (177–470)* |
| 61–71 | 114 | 5 (2–12) | 118 (61–196) | 5 (2–10) | 316 (210–506)$ |
| 71–78 | 119 | 6 (2–13) | 100 (60–193) | 5 (2–12) | 362 (236–510) |
| >78 | 92 | 7 (3–19) | 104 (66–201) | 5 (2–8) | 351 (234–585) |
| Sex | |||||
| women | 229 | 6 (2–16)* | 105 (60–201) | 5 (2–12) | 340 (212–572)* |
| men | 209 | 4 (2–12) | 112 (60–182) | 5 (2–10) | 320 (203–506)$ |
| BMI (kg/m²) | |||||
| <25 | 123 | 5 (1–14) | 98 (60–185)* | 5 (2–10) | 303 (210–504)* |
| >25 | 298 | 5 (2–14) | 115 (60–195) | 5 (2–11) | 341 (203–556) |
| RCRI | |||||
| 1 | 210 | 5 (1–12)* | 104 (58–193) | 5 (2–10) | 317 (201–514) |
| 2 | 63 | 5 (3–17) | 97 (67–160) | 5 (3–9) | 335 (230–476) |
| 3 | 17 | 5 (3–13) | 115 (70–183) | 5 (1–10) | 370 (230–575) |
| 4 | 8 | 9 (6–16) | 125 (64–182) | 4 (2–8) | 408 (306–585) |
| Post op pain score | |||||
| <4 | 55 | 5 (2–12) | 101 (65–187) | 4 (2–9)* | 325 (212–514) |
| >4 | 168 | 5 (1–12) | 97 (58–176) | 5 (3–10) | 316 (201–499) |
| ASA | |||||
| 1 | 10 | 3 (1–12)* | 137 (59–185) | 8 (4–13)* | 399 (193–517) |
| 2 | 291 | 5 (2–13) | 105 (60–201) | 5 (3–11) | 317 (212–515) |
| 3 | 116 | 6 (3–16) | 109 (56–180) | 5 (2–9) | 355 (210–573) |
| 4 | 2 | 8 (7–9) | 121 (92–151) | 5 (5–5) | 412 (365–459) |
| Acetylsalicylic acid | |||||
| No | 290 | 5 (2–13) | 105 (60–194) | 5 (2–11) | 317 (210–506) |
| Stop day-7 | 104 | 5 (2–16) | 114 (66–201) | 5 (2–11) | 355 (203–585) |
| No stop | 30 | 6 (3–18) | 94 (56–149) | 5 (3–9) | 357 (218–558) |
| Clopidogrel | |||||
| No | 403 | 5 (2–14) | 107 (60–195) | 5 (2–11) | 327 (203–527) |
| Yes | 21 | 6 (3–11) | 100 (64–157) | 5 (3–9) | 367 (242–719) |
| Acenocoumarol | |||||
| No | 397 | 5 (2–14)* | 106 (60–194) | 5 (2–11) | 329 (203–527) |
| Yes | 27 | 6 (3–14) | 103 (70–182) | 5 (2–9) | 330 (230–608) |
| No. of levels | |||||
| 1 | 147 | 4 (1–15)* | 80 (53–144)* | 5 (2–12) | 275 (180–485)* |
| 2 | 175 | 5 (3–14) | 110 (70–188) | 5 (2–11) | 353 (238–558)$ |
| 3 | 83 | 6 (3–18) | 130 (77–194) | 5 (3–10) | 361 (273–517) |
| 4 | 29 | 8 (4–12) | 167 (120–310) | 4 (2–8) | 420 (340–514) |
| 5 | 4 | 8 (5–8) | 238 (150–300) | 5 (4–6) | 472 (403–540) |
| Surgical technique | |||||
| Unilateral | 318 | 5 (2–14)* | 98 (58–182)* | 5 (2–10) | 314 (203–527)* |
| Bilateral | 120 | 7 (3–18) | 127 (75–210) | 5 (2–11) | 414 (250–540)$ |
| Synovial cyst | |||||
| No | 383 | 5 (2–15)* | 108 (60–190) | 5 (2–11) | 333 (212–517)* |
| Yes | 55 | 5 (1–15) | 105 (60–240) | 4 (3–10) | 304 (202–574) |
| Foraminotomy | |||||
| No | 384 | 5 (2–14) | 105 (60–193)* | 5 (2–11) | 329 (212–517) |
| Yes | 54 | 5 (1–18) | 120 (67–200) | 5 (2–11) | 355 (168–608) |
| Dural tear | |||||
| No | 409 | 5 (2–14)* | 104 (60–182)* | 5 (2–10) | 320 (206–506)* |
| Yes | 29 | 8 (4–19) | 162 (77–300) | 6 (2–14) | 472 (335–747)$ |
| Epidural haematoma | |||||
| No | 433 | 5 (2–15)* | 107 (60–194) | 5 (2–11) | 329 (206–517)* |
| Yes | 5 | 13 (7–17) | 90 (78–130) | 4 (3–14) | 500 (309–572)$ |
| Wound sepsis | |||||
| No | 434 | 5 (2–15) | 106 (60–193) | 5 (2–11) | 329 (208–522) |
| Yes | 4 | 10 (5–19) | 144 (78–201) | 6 (4–8) | 565 (384–747) |
| Neurological damage | |||||
| No | 437 | 5 (2–15) | 107 (60–194) | 5 (2–11) | 330 (210–527) |
| Yes | 1 | 4 (4–4) | 98 (98–98) | 5 (5–5) | 325 (325–325) |
Significant bold values indicate bivariate analysis and/or modelling
* for p value <0.05 according to Kruskal–Wallis test
$for predictor for the general model TSPP