Table 2.
Mean change in functional outcome at 1- and 2-year follow-up
| Variable | Minimum 12-month follow-up | Minimum 24-month follow-up | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| N | BP | PF | PCS | ODI | N | BP | PF | PCS | ODI | |
| Overall | 144 | 25.1*** (20.2, 30.1) | 21.2*** (15.6, 26.8) | 10.2*** (7.6, 12.8) | 18.3*** (13.9, 22.7) | 70 | 24.8*** (18.1, 31.4) | 21.4*** (12.2, 30.6) | 9.6*** (5.2, 13.9) | 17.9*** (12.0, 23.9) |
| Female | 76 | 24.7 | 21.8 | 10.8 | 19.3 | 34 | 26.5 | 24.8 | 12.8 | 21.6 |
| Male | 68 | 25.6 | 20.5 | 9.6 | 17.3 | 36 | 23.1 | 18.2 | 6.6 | 14.4 |
| Difference (95% CI) | −0.9 (−10.9, 9.2) | 1.3 (−9.9, 12.6) | 1.2 (−3.9, 6.5) | 2 (−6.7, 10.8) | 3.4 (−10.0, 16.7) | 6.6 (−11.9, 25.1) | 6.2 (−2.5, 14.8) | 7.2 (−4.7, 19.1) | ||
| Age >50 | 87 | 23.9 | 17.8 | 8.3 | 16.3 | 46 | 24.2 | 18.8 | 6.2 | 15.2 |
| Age ≤50 | 57 | 27.0 | 26.3 | 12.9 | 21.0 | 24 | 25.8 | 26.2 | 14.9 | 22.8 |
| Difference (95% CI) | −3.1 (−13.3, 7.1) | −8.5 (−19.8, 2.9) | −4.9 (−9.8, 0.6) | −4.7 (−13.5, 4.2) | −1.6 (−15.7, 12.4) | −7.4 (−26.9, 12.0) | −8.7* (−17.4, 0.1) | −7.6 (−20.0, 4.7) | ||
| WCB | 9 | 15.6 | 26.7 | 11.8 | 13.9 | 4 | 17.5 | 31.3 | 16.5 | 19.0 |
| Non-WCB | 135 | 25.8 | 20.8 | 10.1 | 18.6 | 66 | 25.2 | 20.8 | 9.1 | 17.9 |
| Difference (95% CI) | −10.2 (−30.7, 10.2) | 5.9 (−17.3, 29.1) | 1.7 (−9.0, 12.3) | −4.7 (−22.8, 13.4) | −7.7 (−36.3, 20.8) | 10.5 (−29.4, 50.4) | 7.4 (−10.2, 24.9) | 1.1 (−24.2, 26.5) | ||
| Smoker | 10 | 22.0 | 9.0 | 7.1 | 11.4 | 3 | 6.7 | −23.3 | −10.0 | −1.3 |
| Non-smoker | 134 | 25.4 | 22.1 | 10.5 | 18.8 | 67 | 25.6 | 23.4 | 10.6 | 18.8 |
| Difference (95% CI) | −3.4 (−22.9, 16.2) | −13.1 (−35.1, 8.9) | −3.4 (−13.4, 6.7) | −7.4 (−24.5, 9.7) | −18.9 (−51.4, 13.5) | −46.7* (−91.1, −2.3) | −20.6* (−40.1, −1.1) | −20.1 (−48.7, 8.4) | ||
| Multilevel | 56 | 15.5 | 11.1 | 4.3 | 11.6 | 35 | 17.3 | 15.3 | 5.2 | 12.5 |
| Single Level | 88 | 31.3 | 27.6 | 13.7 | 22.8 | 35 | 32.0 | 27.4 | 13.4 | 23.5 |
| Difference (95% CI) | −15.8*** (−25.7, −5.9) | −16.5*** (−27.7, −5.4) | −9.4*** (−14.5, − 4.3) | −11.2** (−19.9, − 2.5) | −14.7* (−27.5, −1.8) | −12.1 (−30.4, 6.2) | −8.2 (−16.7, 0.4) | −11.0 (−22.8, 0.6) | ||
| Fusion | 50 | 20.4 | 18.4 | 8.7 | 10.9 | 21 | 19.5 | 23.6 | 8.5 | 13.7 |
| Decompression | 94 | 27.6 | 22.6 | 11.0 | 21.6 | 49 | 26.9 | 20.4 | 10.0 | 19.7 |
| Difference (95% CI) | −7.2 (−17.7, 3.4) | −4.2 (−16.1, 7.5) | −2.3 (−7.8, 3.2) | −10.7* (−20.0, 1.5) | −7.4 (−22.1, 7.2) | 3.2 (−17.1, 23.4) | −1.5 (−11.3, 8.2) | −6 (−19.1, 6.9) | ||
Null hypothesis: no difference in mean change in functional outcome for binary variables
CI Confidence interval, WCB worker’s compensation board claim, BP mean change in the bodily pain index (SF-36), PF mean change in the physical function index (SF-36), PCS mean change in physical component summary score (SF-36), ODI mean change in Oswestry disability index
* Significant at the P < 0.05 level; ** significant at the P < 0.01 level; *** significant at the P < 0.005 level