Table 2. Comparison of Treatment Groups on Primary and Secondary Outcomes.
| Incisional Negative Pressure Wound Therapya |
Standard Wound Dressinga |
Adjusted Treatment Effect (95% CI) |
P Valueb | |
|---|---|---|---|---|
| Primary Outcome | ||||
| Deep surgical site infection at 30 d, No./Total No. (%) | ||||
| Randomized population | 45/770 (5.84) | 50/749 (6.68) | OR, 0.87 (0.57 to 1.33) | .52 |
| Per-protocol population | 41/668 (6.14) | 48/731 (6.57) | OR, 0.93 (0.60 to 1.44) | .76 |
| Primary analysis population | 46/784 (5.87) | 51/763 (6.68) | OR, 0.86 (0.57 to 1.31) | .49 |
| Secondary analysis of primary outcome at 90 d in randomized population, No./Total No. (%) | 72/629 (11.4) | 78/590 (13.2) | OR, 0.84 (0.59 to 1.19) | .32 |
| Self-Reported Secondary Outcomes | ||||
| Disability Rating Index, mean (95% CI)c | ||||
| At 3 mo | (n = 507) 51.6 (49.5 to 53.6) |
(n = 456) 51.1 (48.9 to 53.3) |
MD, −0.01 (−2.79 to 2.78) | >.99 |
| At 6 mo | (n = 469) 40.6 (38.3 to 42.8) |
(n = 432) 40.2 (37.7 to 42.8) |
MD, 0.03 (−2.82 to 2.88) | .98 |
| Health-related quality of life assessed by EuroQol 5-level EQ-5D, mean (95% CI)d | ||||
| At 3 mo | (n = 528) 0.50 (0.47 to 0.52) |
(n = 470) 0.49 (0.47 to 0.52) |
MD, 0 (−0.03 to 0.04) | .84 |
| At 6 mo | (n = 486) 0.58 (0.55 to 0.60) |
(n = 446) 0.58 (0.55 to 0.60) |
MD, 0 (−0.03 to 0.04) | .86 |
| Visual analog scale on EuroQol 5-level EQ-5D, mean (95% CI)e | ||||
| At 3 mo | (n = 531) 64.1 (62.2 to 66.0) |
(n = 478) 64.7 (62.7 to 66.8) |
MD, −0.73 (−3.30 to 1.84) | .58 |
| At 6 mo | (n = 489) 69.7 (67.8 to 71.5) |
(n = 449) 69.4 (67.4 to 71.5) |
MD, 0.08 (−2.57 to 2.74) | .95 |
| Scar assessment score, mean (95% CI)f | ||||
| At 30 d | (n = 657) 4.35 (4.15 to 4.56) |
(n = 616) 4.58 (4.37 to 4.79) |
MD, −0.18 (−0.46 to 0.10) | .22 |
| At 3 mo | (n = 523) 4.71 (4.47 to 4.95) |
(n = 470) 4.86 (4.61 to 5.11) |
MD, −0.11 (−0.41 to 0.20) | .51 |
| At 6 mo | (n = 483) 4.61 (4.36 to 4.86) |
(n = 437) 4.52 (4.27 to 4.77) |
MD, 0.11 (−0.21 to 0.42) | .52 |
| Chronic neuropathic pain assessed by Douleur Neuropathique Questionnaire, No./Total No. (%)g | ||||
| At 3 mo | 113/362 (31.2) | 109/339 (32.2) | OR, 0.94 (0.68 to 1.31) | .72 |
| At 6 mo | 117/414 (28.3) | 117/367 (31.9) | OR, 0.84 (0.61 to 1.15) | .27 |
Abbreviations: MD, mean difference; OR, odds ratio.
Adjusted for open vs closed wounds, Injury Severity Score, participant age, sex, and, when appropriate, baseline scores (Disability Rating Index; health-related quality of life and visual analog scale on EuroQol 5-level EQ-5D) as fixed effects, and for randomizing center as a random effect. As a sensitivity analysis, multiple imputation was used for missing primary outcome data under the missing at random assumption.
Calculated from mixed-effects logistic regression models for binary variables and from repeated-measures mixed-effects linear regression models for continuous variables.
Range, 0 to 100; higher scores indicate less disability. Scores were calculated as a mean across all 12 questions and were imputed for participants who answered at least 10 questions.
Range, −0.594 to 1; higher scores indicate better quality of life. Scores were converted to multiattribute utility values using the crosswalk and EQ-5D-3L value sets.
Range, 0 to 100; higher scores indicate better quality of life.
Range, 1 to 10; 1 indicates normal skin; 10, very different from normal skin.
Binary measure of neuropathic pain. If a participant responded yes to 3 or more of the 7 questions about pain characteristics, neuropathic pain was considered to be present. Data were available for the randomized population.