Search strategy and evidence selection

Search strategy and evidence selection

Search strategy

The search strategy was designed to identify evidence on the clinical and cost effectiveness of the Mobi‑C cervical disc. To maximise sensitivity the strategy comprised of 1 concept only; the intervention. The title, abstract, author keyword and address fields were searched for the brand name of the device and the name of the manufacturer. A broader search to capture studies of interest which may not explicitly name the device in the title, abstract or other fields of the database record was not feasible within the context of this project. A search for all studies describing the use of artificial cervical discs or cervical disc replacement procedures would have returned a volume of literature requiring full text review beyond that which could be assessed within the scope of a medtech innovation briefing. This reflects the relatively large evidence base and number of competitor devices in this field. To test the 1 concept search strategy, the results using this strategy were compared against the 5 known relevant studies identified by NICE, and all 5 studies were retrieved in MEDLINE and EMBASE. Searching using only the device and manufacturer's name also found all of the relevant 14 studies included in a 2014 review of Mobi‑C (Alvin et al. 2014).

The strategy excluded animal studies using a standard algorithm. Non‑English language publications were also excluded from the search results. The search was restricted to studies published from 2004 to date. This reflects the date the device was CE marked. The following databases were searched:

  • Cochrane Central Register of Controlled Trials (Cochrane Library, Wiley)

  • Cochrane Database of Systematic Reviews (Cochrane Library, Wiley)

  • Database of Abstracts of Reviews of Effects (Cochrane Library, Wiley)

  • Embase (Ovid SP)

  • Health Technology Assessment Database (Cochrane Library, Wiley)

  • MEDLINE and MEDLINE in Process (Ovid SP)

  • NHS Economic Evaluation Database (Cochrane Library, Wiley)

  • PubMed.

Evidence selection

A total of 261 records were retrieved from the literature search. After de‑duplication, 182 records remained for assessment. One recently published study, not included in any of the resources searched as of 2 March 2016 due to its publication date, was additionally provided by the device manufacturer, taking the total number of records to 183. The title and abstracts of all 183 records were screened independently by 2 reviewers, against the inclusion and exclusion criteria listed below:

Inclusion criteria:

  • Includes the 1 level or 2 level Mobi‑C cervical disc.

  • Comparative studies, including systematic reviews and meta‑analysis.

  • Paper records at least 1 outcome measure (for example, not an opinion piece), including, but not limited to: patient mobility score, occurrence of adjacent segment disease, rate of adjacent segment degeneration, rate of revision surgery.

Exclusion criteria:

  • Non‑English language studies.

  • Conference abstracts.

  • Review protocols.

  • Low patient numbers (that is n<15).

During the first sift 136 papers were excluded, with initial disagreements resolved following discussions between the 2 reviewers. Following the first sift a further 28 papers were excluded as they were identified to be conference abstracts. Full records were retrieved for the remaining 19 papers and a second sift was undertaken against the same inclusion and exclusion criteria. Again, disagreements between the 2 reviewers were resolved through discussion, with a further 7 papers were excluded for:

  • No data specific to Mobi‑C (n=3).

  • Low patient numbers (n=2).

  • Non‑comparative study (n=1).

  • Not a clinical evaluation (n=1).

Of the remaining 12 papers, 5 were selected for inclusion in this briefing. One of the papers was a systematic review and 2 reported on long‑term follow‑up data of 2 RCTs, whose shorter term data had been published previously. The other 7 papers were excluded for the following reasons:

  • Study assessed in the included systematic review (n=5).

  • Longer term follow‑up data presented in included RCT (n=1).

  • Comparison of 1‑level vs 2‑level Mobi‑C, rather than Mobi‑C vs comparator (n=1).