Table 3.
Evidence-profile: efficacy and safety of cervical artificial disc versus fusion
| No. of studies/patients | Design | Methodological quality | Consistency of results | Directness | Effect size | Other modifying factorsa | Level of evidence |
|---|---|---|---|---|---|---|---|
| Outcome: NDI; 24 months | |||||||
| 4/1,481 | RCT | Fair/poorb | Yes | Direct | Improvement in both groups; slightly better but mostly insignificant improvement in CTDR-group | No | Moderate |
| Outcome: Pain VAS; (1) 24 months; (2) 36 months | |||||||
| (1) 4/905 | (1) RCT | (1) Poorb | (1) Yes | Direct | (1) Improvement in both groups; slightly better but only partly significant improvement in CTDR-group | No | Moderate |
| (2) 1/49 | (2) RCT | (2) Poorb | (2) Only 1 study | Direct | (2) No difference between groups | ||
| Outcome: SF-36; 24 months | |||||||
| 4/1,481 | RCT | Fair/poorb | Yes | Direct | Improvement in both groups; CRI unclear; no sign. difference (except physical component in one study) between groups | No | Moderate |
| Outcome: Neurological success; 24 months | |||||||
| 3/1,416 | RCT | Fair/poorb | Yes | Direct | Improvement in both groups (~90% of patients), slightly better but mostly insignificant improvement in CTDR-group | No | Moderate |
| Outcome: satisfaction; 24 months | |||||||
| 1/209 | RCT | Fairc | Yes | Direct | Both groups highly satisfied, no sign. difference between groups | No | Moderate |
| Outcome: overall success; 24 months | |||||||
| 3/1,416 | RCT | Fair/poorb | Yes | Direct | Slightly and significantly more (max. 83%) reached success criterion in CTDR-group compared with Fusion group (max. 73%) | No | Moderate |
| Outcome: (1) employment rate; 24 months; (2) return to work; 24 months | |||||||
| (1) 3/1,416 | (1) RCT | (1) Fair/poorb | Yes | Direct | (1) ~3/4 in both groups employed, no sign. difference between groups | No | Moderate |
| (2) 2/834 | (2) RCT | (2) Fairb | Direct | (2) CTDR-group returned to work sign. earlier (~15 days) | |||
| Outcome: Complications; 24 months | |||||||
| 7/2,591 | RCT | Fair/poorb | Yes | Direct | Secondary surgical procedure: 2–5% CTDR-group; 3–9% fusion group. Implant(ation)-related complications: 3% CTDR-group; 5–7% fusion group. Serious adverse events: 2–13% CTDR-group; 3–21% fusion group. General adverse events: 3–34% CTDR group; 3–29% fusion group. Operation-related events: 15% CTDR group; 15% fusion group. SADD: 0–1% CTDR group; 1–15% fusion group | No | Moderate |
SADD symptomatic adjacent disc disease, CTDR group cervical total disc replacement group, sign. significant, d days, CRI clinically relevant improvement
aLow incidence, lack of precise data, strong or very strong association, high risk of reporting bias, dose-efficacy gradient, residual confounding plausible
bITT-Analysis not conducted or not stated; treatment groups at baseline only partly comparable or baseline characteristics not stated; no blinding of outcome assessment; drop-out rate >20%; non-inferiority design problematic
cNo blinding of outcome assessment; ITT-Analysis not stated