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Currently accepted at: JMIR Research Protocols

Date Submitted: Aug 19, 2019
Open Peer Review Period: Aug 19, 2019 - Sep 17, 2019
Date Accepted: Sep 23, 2019
(closed for review but you can still tweet)

This paper has been accepted and is currently in production.

It will appear shortly on 10.2196/15922

The final accepted version (not copyedited yet) is in this tab.

Tackling Research Inefficiency in Degenerative Cervical Myelopathy: illustrating the current challenges for research synthesis

  • Danyal Zaman Khan; 
  • Muhammad Shuaib Khan; 
  • Mark R.N. Kotter; 
  • Benjamin Marshall Davies; 



Degenerative cervical myelopathy (DCM) is widely accepted as the most common cause of adult myelopathy worldwide. Despite this, there remains no specific term or diagnostic criteria in the ICD-11 and no medical subject headings (MeSH) or equivalent in common literature databases. This makes searching the literature and thus, conducting systematic reviews and/or meta-analyses (SR/MA) imprecise and inefficient. Efficient research synthesis is integral to delivering evidence-based medicine and improving research efficiency.


This study sought to illustrate the difficulties encountered when attempting to carry out comprehensive and accurate evidence search in the field of DCM, by identifying the key sources of imprecision and quantifying their impact.


In order to identify the key sources of imprecision and quantify their impact, an illustrative search strategy was formed using a validated DCM HEDGE combined together with contemporary strategies used by authors in previous SR/MA. This strategy was applied to MEDLINE and EMBASE databases, looking for relevant DCM SR/MA published within the last 5 years.


The MEDLINE via PubMed search strategy (Figure 1) returned 24,166 results, refined to 534 after application of inclusion and exclusion criteria. 176 (32.96%) results were about DCM, 97 (18.16%) of these were DCM SR/MA (Table 1). Non-DCM results were organized into imprecision categories (spinal 50.2%, non-spinal 15.5%, non-human 1.5%). The largest categories were spinal cord injury (13.67%), spinal neoplasms (8.24%), infectious diseases of the spine and CNS (3.37%) and other spinal levels (thoracic, lumbar, sacral) (3.37%). Counterintuitively, the use of “human” and “adult” PubMed filters was found to exclude a large number of relevant articles. Searching a second database (EMBASE), added an extra 12 DCM SR/MA articles.


DCM search strategies face significant imprecision, principally due to overlapping and heterogenous search terms, and inaccurate article indexing. Notably common employed MEDLINE filters, ‘Human’ and ‘Adult’ reduced search sensitivity, whereas the related articles function and use of a second database (EMBASE) improved it. Development of a MeSH labelling and a standardized DCM definition would allow comprehensive and specific indexing of DCM literature. This is required to support a more efficient research synthesis.


Please cite as:

Khan DZ, Khan MS, Kotter MR, Davies BM

Tackling Research Inefficiency in Degenerative Cervical Myelopathy: illustrating the current challenges for research synthesis

DOI: 10.2196/15922


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