A new study published in Spine examines the observational studies focused on cervical disc arthroplasty and compared the results to randomized controlled trials.
The researchers examined electronic databases from 2000 to 2014 with The Neck Disability Index as the primary outcome for the standardized pre- and post mean difference.
There were nine randomized controlled trials and 28 observational studies as well as one hybrid study for meta-analysis. The researchers found:
1. The standardized pre-and-post mean difference — Hedge's g — for NDI score was 2.15 for randomized controlled trials and 2.03 for observational studies. The difference wasn't significant.
2. There wasn't a significant difference for secondary outcomes found between the two trial types. But the prospective observational studies reported less treatment effect in visual analog scale neck — 1.6 — compared with randomized controlled trials — 2.11.
3. The randomized controlled trials recruited younger patients — 44 years old compared with 45.6 years old in the non-randomized observational studies.
4. The patients in the randomized controlled studies also had a worse NDI score — 54.3 — at baseline than the observational study patients — 46.92.
5. The patients who underwent surgery with the ProDisc-C reported less standardized NDI improvement at 1.41, than the patients with the Prestige disc, 2.48.
"Prospective observational studies that utilize the same features of RCTs such as inclusion and exclusion criteria validated clinical outcomes, and statistical methods can provide valuable information about the treatment effects on a generalized population," concluded the study authors.