Impact of body mass index on MCID achievement.
| PROM | 6 wk | 12 wk | 6 mo | 1 y | 2 y | Overall |
| VAS back | n = 89 | n = 85 | n = 82 | n = 16 | n = 8 | n = 146 |
| Nonobese | 43.4% (56) | 44.7% (38) | 45.1% (37) | 12.5% (2) | 37.5% (3) | 45.9% (67) |
| Obese I | 31.5% (28) | 31.7% (27) | 29.3% (24) | 43.8% (7) | 37.5% (3) | 27.4% (40) |
| Severe + morbid | 23.6% (21) | 23.5% (20) | 25.6% (21) | 43.8% (7) | 25.0% (2) | 26.7% (39) |
| P valuea | 0.425 | 0.279 | 0.783 | 0.106 | 0.184 | 1.000 |
| VAS leg | n = 31 | n = 30 | n = 38 | n = 13 | n = 9 | n = 59 |
| Nonobese | 38.7% (12) | 40.0% (12) | 44.7% (17) | 30.8% (4) | 33.3% (3) | 39.0% (23) |
| Obese I | 38.7% (12) | 30.0% (9) | 29.0% (11) | 38.5% (5) | 22.2% (2) | 28.8% (17) |
| Severe + morbid | 22.6% (7) | 30.0% (9) | 26.3% (10) | 30.8% (4) | 44.4% (4) | 32.2% (19) |
| P valuea | 0.323 | 0.830 | 0.701 | 0.646 | 0.866 | 0.424 |
| Owestry Disability Index | n = 19 | n = 24 | n = 39 | n = 15 | n = 5 | n = 50 |
| Nonobese | 31.6% (6) | 29.2% (7) | 38.5% (15) | 6.7% (1) | 20.0% (1) | 34.0% (17) |
| Obese I | 26.3% (5) | 25.0% (6) | 25.6% (10) | 40.0% (6) | 0.0% (0) | 24.0% (12) |
| Severe + morbid | 42.1% (8) | 45.8% (11) | 35.9% (14) | 53.3% (8) | 80.0% (4) | 42.0% (21) |
| P valuea | 0.640 | 0.339 | 0.823 | 0.053 | 0.230 | 0.023 |
| 12-Item Short Form physical composite score | n = 16 | n = 20 | n = 17 | n = 19 | n = 11 | n = 48 |
| Nonobese | 50.0% (8) | 40.0% (8) | 52.9% (9) | 31.6% (6) | 45.5% (5) | 37.5% (18) |
| Obese I | 25.0% (4) | 30.0% (6) | 29.4% (5) | 26.3% (5) | 36.4% (4) | 33.3% (16) |
| Severe + morbid | 25.0% (4) | 30.0% (6) | 17.7% (3) | 42.1% (8) | 18.2% (2) | 29.2% (14) |
| P valuea | 0.445 | 0.891 | 0.484 | 0.587 | 0.631 | 0.409 |
| PROMIS-PF | n = 8 | n = 9 | n = 14 | n = 13 | n = 7 | n = 26 |
| Nonobese | 75.0% (6) | 66.7% (6) | 50.0% (7) | 23.1% (3) | 42.9% (3) | 38.5% (10) |
| Obese I | 25.0% (2) | 33.3% (3) | 28.6% (4) | 30.8% (4) | 28.6% (2) | 30.8% (8) |
| Severe + morbid | 0.0% (0) | 0.0% (0) | 21.4% (3) | 46.2% (6) | 28.6% (2) | 30.8% (8) |
| P valuea | 0.096 | 0.076 | 0.376 | 0.571 | 0.927 | 0.723 |
Abbreviations: MCID, minimum clinically important difference; PROM, patient-reported outcome measure; PROMIS-PF, Patient-Reported Outcome Measurement Information System physical function.
Note: Boldface indicates statistical significance.
↵a P values calculated using χ2 analysis.