Table 2. Comparison of Arm Pain and Secondary Outcome Measures Between Posterior and Anterior Surgery.
| Variablea | Mean (SD) | Mean difference (95% CI)b | |
|---|---|---|---|
| Posterior surgery (n = 119) | Anterior surgery (n = 124) | ||
| VAS score, arm | |||
| Baseline | 62.3 (20.7) | 60.3 (22.1) | NA |
| 1 y | 18.6 (22.9) | 15.8 (23.7) | –2.8 (–9.4) |
| Change | 41.9 (29.5) | 45.3 (29.7) | 3.4 (11.8) |
| VAS score, neck | |||
| Baseline | 55.2 (22.4) | 53.6 (23.7) | NA |
| 1 y | 24.4 (27.5) | 21.7 (26.1) | –2.7 (–10.3 to 4.8) |
| Change | 29.5 (33.9) | 31.6 (29.2) | 2.1 (–6.9 to 11.1) |
| NDI score | |||
| Baseline | 43.6 (14.1) | 42.2 (13.5) | NA |
| 1 y | 17.6 (14.6) | 19.2 (16.5) | 1.5 (–2.9 to 5.9) |
| Change | 24.3 (15.8) | 23.1 (16.8) | –1.2 (–5.8 to 3.5) |
| WAS score | |||
| Baseline | 3.8 (2.5) | 3.8 (2.5) | NA |
| 1 y | 6.7 (2.3) | 6.7 (2.6) | –0.09 (–0.80 to 0.60) |
| Change | 2.7 (2.8) | 2.7 (3.1) | –0.01 (–0.90 to 0.80) |
| EQ-5D-5L score | |||
| Baseline | 0.61 (0.18) | 0.62 (0.20) | NA |
| 1 y | 0.84 (0.15) | 0.82 (0.14) | –0.02 (–0.06 to 0.02) |
| Change | 0.20 (0.17) | 0.19 (0.22) | –0.01 (–0.06 to 0.05) |
| Reported satisfied or very satisfied, No. (%)c | |||
| Baseline | NA | NA | NA |
| 1 y | 70 (73) | 76 (77) | 0.04 (–0.09 to 0.20) |
| All adverse events, No. (%)d | |||
| Baseline | NA | NA | NA |
| 1 y | 36 (30) | 35 (28) | –0.02 (–0.10 to 0.10) |
| Surgery-associated adverse events, No. (%)d | |||
| Baseline | NA | NA | NA |
| 1 y | 26 (22) | 22 (18) | –0.04 (–0.10 to 0.07) |
| All serious adverse events, No. (%)d | |||
| Baseline | NA | NA | NA |
| 1 y | 13 (11) | 17 (14) | 0.03 (–0.06 to 0.10) |
| Surgery-associated serious adverse events, No. (%)d | |||
| Baseline | NA | NA | NA |
| 1 y | 7 (6) | 7 (6) | –0.00 (–0.06 to 0.06) |
| Reoperations, No. (%) | |||
| Baseline | NA | NA | NA |
| 1 y | 6 (5) | 4 (3) | –0.02 (–0.08 to 0.04) |
Abbreviations: EQ-5D-5L, EuroQol 5-Dimensions 5-Level questionnaire; NA, not applicable; NDI, Neck Disability Index; VAS, visual analogue scale; WAS, Work Ability Index–single item.
Data on baseline variables were available for 112 in the posterior surgery group and 117 in the anterior surgery group. Data after 1-year follow-up were available for 96 patients in the posterior surgery group and 99 in the anterior surgery group. There were no missing data for serious adverse events and reoperations.
Two-sided 95% CIs are given for the mean difference in change score from baseline to 1 year after surgery for patients in the posterior and anterior surgery groups, except for the following variables: VAS score for arm pain, treatment satisfaction, serious adverse events, and reoperations. For the outcomes in arm pain, a 1-sided 95% CI with Bonferroni correction was reported. For the other outcomes, the reported 95% CI denotes the difference in score after 1 year of follow-up between the posterior and anterior surgery groups, respectively.
In a questionnaire of overall satisfaction at 1-year follow-up, patients responded to the question, “How satisfied are you with the results of the surgery?” The 7-point answer options were “very satisfied,” “satisfied,” “moderately satisfied,” “somewhat satisfied/not satisfied,” “slightly dissatisfied,” “dissatisfied,” and “very dissatisfied.” The number of patients who answered with “very satisfied” and “satisfied” is depicted.
Adverse events were considered serious if lethal, life threatening, required hospitalization, caused considerable disability, were a congenital anomaly or birth defect, or any other medically important event that jeopardized the patient or required intervention. All serious adverse events were calculated at the patient level. For an overview of complication level, see Table 3 and eTable 7 in Supplement 4.