Evidence Review Process

PROSPECT C-Section Subgroup and Working Group process

For each review, a Subgroup of the PROSPECT Working Group performs an initial evaluation of the evidence and also drafts clinical practice statements and recommendations, which are then discussed by the whole Working Group before a final consensus is reached. For the C-Section review, the Subgroup members were:

• Professor Marc Van De Velde (PROSPECT Working Group member)
• Professor Girish Joshi (PROSPECT Working Group member)
• Professor Narinder Rawal (PROSPECT Working Group member)
  

Dr Thomas Jaschinski (IFOM - Institut für Forschung in der Operativen Medizin, Universität Witten/Herdecke, Köln, Germany) provided support in conducting the literature search, preparing the evidence summary and coordinating the Subgroup and Working Group reviews of the evidence to prepare the final recommendations. The recommendations for postoperative pain management in C-Section were voted on by nine Working Group members to show the strength of consensus. The results of each vote are indicated within the PROSPECT recommendations sub-folders.

Literature search

• Systematic review of the literature from 1966–April 2014 using MEDLINE and EmBASE, following the protocol of the Cochrane Collaboration
• Inclusion of randomised/controlled studies assessing analgesic, anaesthetic or operative techniques in C-Section and reporting pain assessment, required analgesia or adverse events (C-Section: Inclusion criteria, C-Section: Search strategy)
• 137 studies included (C-Section: Included studies)
• 139 studies excluded after full-text screening (C-Section: Excluded studies)
• The most common reason for exclusion was that the study did not investigate an intervention affecting postoperative pain (63 studies)

C-Section: 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:
C-Section: 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
• Transferable evidence from comparable procedures, or from other relevant sources, identified by the members of the prospect Working Group
• 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 C-Section 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, HigginsandGreen 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 C-Section review are summarised:

• C-Section: Methodological quality summary and level of evidence

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

• C-Section: Critical appraisal of systematic reviews

Quantitative analyses

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.

Transferable evidence

Transferable evidence has not been included in the C-Section review as there was sufficient procedure-specific evidence on which to base the recommendations for the most common analgesic interventions.