Table 6.
Evidence Summary.
| Studies; N [References] | Strength of Evidence | Conclusions/Comments | |
|---|---|---|---|
| Key Question 1: What are the expected functional, disability and pain outcomes following surgical intervention for DCM? | |||
| JOA/mJOA | 6-12 months 10 studies [20, 22-24, 28, 30, 32, 34, 45, 48] (N = 1697) 13–36 months 12 studies [17, 23, 30-34, 37, 40, 44, 47, 48] (N = 2267) ≥36 months 7 studies [18-20, 23, 39, 44, 46] (N = 1088) | Moderatea | Surgical intervention resulted in improved JOA/mJOA scores at all time points assessed. Pooled standardized mean differences showed a large effect for improvement in function from baseline at short term (10 studies, SMD 1.92), medium term (12 studies, SMD 1.40), and long term (7 studies, SMD 1.92) follow-up. |
| NDI | 6-12 months 5 studies [20, 22, 35, 44, 48] (N = 1211) 13-36 months 5 studies [20, 35, 44, 47, 48] (N = 1347) ≥36 months 2 studies [18, 20] (N = 328) | Very Lowb | Surgical intervention resulted in improved NDI scores at all time points assessed. Pooled mean differences showed clinically meaningful improvement in disability from baseline at short term (5 studies, MD 18.02), medium term (5 studies, MD 19.71), and long term (2 studies, MD 23.21) follow-up. |
| Nurick | 6-12 months 2 studies [22, 48] (N = 739) 13-36 months 4 studies [29, 38, 43, 48] (N = 758) | Low | Surgical intervention resulted in improved Nurick scores at short-term and medium-term assessments. Pooled mean differences showed clinically meaningful improvement in disability from baseline at short term (2 studies, MD 1.42) and medium term (4 studies, MD 1.06) follow-up. |
| Pain (VAS 100-point scale) | 6-12 months 4 studies [20, 30, 34, 44] (N = 646) 13-36 months 6 studies [20, 30, 34, 35, 44, 47] (N = 1097) ≥36 months 1 study [20] (N = 268) | Moderatea 6-12 months Very Lowb 13-36 and ≥36 months | Surgical intervention resulted in improved pain scores at all time points assessed. Pooled mean differences showed clinically meaningful improvement in pain from baseline at short term (4 studies, MD 32.7), medium term (6 studies, MD 32.5), and long term (1 study, MD 40.0) follow-up. |
| Key Question 2: Do these expected outcomes depend on preoperative disease severity or duration of symptoms? | |||
| Preoperative Duration of Symptoms | |||
| JOA improvement | 12 months 2 studies [26, 39] (N = NC) 24-36 months 1 study [39] (N = 98) 54-60 months 2 studies [19, 39] (N = NC) | Very Lowc | Change in neurological status following surgical intervention does not depend on preoperative duration of symptoms. Patients with a longer duration of symptoms (≥12 months) had similar neurological improvement as those with a shorter duration of symptoms (<12 months) at all follow-up periods. |
| Success (mJOA ≥16) | 1 study [41] (N = 272) F/U 12 months | Low | The odds of a “successful” outcome following surgical intervention depend on preoperative duration of symptoms. The odds of achieving a mJOA ≥16 decreased by 22% when a patient moves from a shorter to a longer duration of symptoms group (≤3; >3, ≤6; >6, ≤12; >12, ≤24; >24 months). |
| Preoperative Myelopathy Severity | |||
| JOA improvement | 1 study [22] (N = 260) F/U 12 months | Moderated | Change in neurological status following surgical intervention depends on preoperative disease severity. Less improvement on the mJOA was observed among patients with milder symptoms at presentation (preoperative mJOA ≥15: 1.29 [95% CI 0.70, 1.87]; preoperative mJOA 12-14: 2.58 [2.07, 3.09]; preoperative mJOA <12: 4.91 [4.34, 5.49]). |
| Success mJOA ≥16 at F/U; 2-point improvement in mJOA | 2 studies [37, 41] (N = 332) F/U 12 months | Low | The odds of a “successful” outcome following surgical intervention depends on preoperative disease severity. The odds of achieving a mJOA ≥16 were 1.22 times greater for every 1-point increase in preoperative mJOA score. |
| % improved mJOA | 1 study [20] (N = 268) F/U 96 months | Very lowb | Likelihood of neurological improvement following surgical intervention does not depend on preoperative disease severity. Similar fractions of patients improved by 1 mJOA point when comparing patients with moderate (mJOA 10-13, 86.7%) and severe (mJOA 5-9, 86.5%) disease. |
| NDI improvement | 1 study [22] (N = 260) F/U 12 months | Very lowc | Similar improvements in NDI across preoperative disease severities following surgical intervention. At 12-months follow-up, NDI changes were 12.1 (mild mJOA ≥15), 9.8 (moderate mJOA 12-14), and 12.5 (severe mJOA <12). |
| Nurick improvement | 1 study [22] (N = 260) F/U 12 months | Very lowc | Similar improvements in Nurick scores across preoperative disease severities following surgical intervention. At 12-months follow-up, the Nurick score changes were 1.6 (mild mJOA ≥15), 1.5 (moderate mJOA 12-14), and 1.7 (severe mJOA <12). |
| Key Question 3: What are the complications associated with surgical intervention? | |||
| C5 radiculopathy or palsy | 15 studies [17, 20, 21, 23-25, 27, 28, 30-32, 36, 40, 42, 48] (N = 2661) | Low | Pooled cumulative incidence of C5 radiculopathy or palsy is 1.9% (95% CI 1.4, 2.4). |
| Infection | 10 studies [20, 21, 24, 27, 29-31, 33, 42, 48] (N = 2074) | Low | Pooled cumulative incidence of infection is 1.5% (95% CI 1.0, 2.1) |
| Reoperation | 7 studies [20, 21, 23, 29, 30, 32, 35] (N = 943) | Very lowe | Pooled cumulative incidence of reoperation 1.4% (95% CI 0.6, 2.1) |
| Dural tear/CSF leak | 11 studies [20, 21, 24, 27, 28, 30-34, 43, 45] (N = 1893) | Very lowc | Pooled cumulative incidence of dural tear is 1.4% (95% CI 0.8, 1.9) |
| Worsening of myelopathy | 2 studies [21, 48] (N = 781) | Very lowc | Pooled cumulative incidence of worsening of myelopathy is 1.3% (95% CI 0.5, 2.1) |
| Death | 6 studies [17, 18, 21, 30, 31, 48] (N = 1162) | Very lowc | Pooled cumulative incidence of mortality is 0.3% (95% CI 0.0, 0.5) |
| Fracture | 1 study [27] (N = 141) | Very lowc | Pooled cumulative incidence of fracture is 2.1% (95% CI 0.0, 4.5) |
Abbreviations: CI, confidence interval; CSF, cerebrospinal fluid; F/U, follow-up; JOA, Japanese Orthopaedic Association score; mJOA, modified Japanese Orthopaedic Association score; NDI, Neck Disability Index.
aUpgraded 1 for magnitude of effect.
bDowngraded 1 for serious risk of bias.
cDowngraded 1 for serious risk of imprecision.
dUpgraded 1 for dose response.
eDowngraded 1 for serious risk of bias and imprecision.