Evidence Review Process - ESRA
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Open Colorectal Surgery 2016

Evidence Review Process

An explanation of PROSPECT methodology and Working Group processes can be found at the following link: PROSPECT methodology primer

For the colorectal surgery review, the Subgroup members were:

Merel van Lieshout
Else Ouweneel
Dr Phillip Lirk (PROSPECT Working Group Member)
Dr Andrew Hill (former PROSPECT Working Group Member)
Prof Girish P. Joshi (PROSPECT Working Group Member)

Literature search

Search history

  • The first PROSPECT review included a total of 80 studies of analgesic interventions in colorectal surgery (published 1966 to March 2009) (see Archive on http://esraeurope.org/prospect)

Colorectal surgery: Sources and levels of evidence (LoE) determine the grades of recommendation (GoR)

GoR are assigned according to the overall LoE, which is determined by the quality of studies cited, the consistency of evidence and the source of evidence:
Colorectal surgery: levels of evidence and grades of recommendation

Sources of evidence in PROSPECT

The evidence for PROSPECT is derived from three separate sources, and this evidence is taken into consideration by the PROSPECT Working Group to determine the PROSPECT recommendations:

  • Procedure-specific evidence derived from the systematic reviews of the literature
  • Current practice – A commentary on the interventions from the members of the PROSPECT Working Group
  • Practical PROSPECT recommendations are based on all the information

 Study quality assessment

For the colorectal surgery review, the quality of procedure-specific evidence has been assessed according to NICE methodology, to determine the possibility of selection bias, performance bias, attrition bias and detection bias (http://www.nice.org.uk/article/pmg6b).

Quality indicators used to determine the LoE of individual studies:

  • Allocation concealment: indicates whether there was adequate prevention of foreknowledge of treatment assignment by those involved in recruitment (in the table below, A=adequate, B=unclear, C=inadequate, D=not used). Empirical research has shown that trials with inadequate or unclear allocation concealment report significantly greater estimates of treatment effect than those trials in which concealment was adequate (Chalmers 1983, Schulz 1995, Moher 1998). Allocation concealment was found to be more important for preventing bias than other aspects of study quality, such as generation of the allocation sequence and double-blinding (Chalmers 1983, Schulz 1995, Moher 1998, Higgins and Green 2005, http://handbook.cochrane.org/)
  • Statistical analyses and patient follow-up: indicates whether statistical analyses were reported, and whether patient follow-up was greater or less than 80%.
  • Numerical scores (total 1–5) for study quality: assigned using the method proposed by Jadad 1996, to indicate whether a study reports appropriate randomisation, double-blinding and statements of possible withdrawals. Empirical research found that low-quality trials were associated with an increased estimate of treatment benefit compared with high-quality trials (Moher 1998)

Study quality assessments for the Colorectal surgery review are summarized:

For systematic reviews, a critical appraisal was performed to determine the LoE:

No meta-analyses were performed due to a limited number of studies of homogeneous design that reported similar outcome measures. Therefore, the procedure-specific evidence was only assessed qualitatively.