Performing the Systematic Review

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  • A systematic search for literature specific to perioperative pain management for the selected procedure is performed in accordance with the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) recommendations.
  • Several electronic databases are searched, including EMBASE, MEDLINE, PubMed and Cochrane Databases (Cochrane Central Register of Controlled Trials, Cochrane Database of Abstracts or Reviews of Effects, Cochrane Database of Systematic Reviews).
  • Broad search terms are used to reduce the risk of missing relevant publications. Search terms include words or phrases associated with specific procedures, possible interventions and pain-related outcomes.
  • Reference lists of the relevant articles are manually screened to identify additional eligible studies that may have been missed in the initial literature search.
  • The time period for the literature search for a new review is determined by the PWG, generally the preceding 10 years; for updates the period is usually 3–5 years from the end-date of the previous review.
  • Inclusion criteria are randomised controlled clinical trials (RCTs) and systematic reviews or meta-analyses of analgesic, anaesthetic or surgical interventions, published in the English language, and addressing pain management relating to the surgical procedure being reviewed.
  • Included RCTs should report pain scores using a linear pain scale, such as the visual analogue scale or verbal or numerical rating scale.
  • Studies reporting data pooled from patients undergoing mixed surgical procedures are excluded if data tables specifically related to the surgical procedure being reviewed cannot be obtained.
  • Two reviewers independently screen the titles and abstracts.
  • Included studies then undergo full-text review and irrelevant papers are excluded.
  • At any stage, in the event of disagreement between the two reviewers, the opinion of a third reviewer is obtained.
  • A PRISMA flow chart is used to present the results of the search data, records screened, records excluded with reasons for exclusion, and studies included in the qualitative analyses.
  • The studies undergo quality assessments which are used to assign the level of evidence.
  • Criteria employed for quality assessments include:
    • Allocation concealment of treatment assignment by those involved in recruitment (A, adequate; B, unclear; C, inadequate; D, not used)
    • Quality scoring using the Jadad score (1–5) to assess randomisation, blinding, and reporting of the flow of patients
    • Participant follow-up of greater or less than 80%.
  • Relationship between quality and source of evidence, levels of evidence and recommendation grade:
    Study type Study quality assessments Grade of recommendation
    Allocation concealment (A–D) Jadad score Statistical analyses and patient follow-up Level of evidence
    Systematic review with homogeneous results NA NA NA 1 A
    Randomised controlled trial A or B 1–5 Statistics reported and >80% follow-up 1 A
    Randomised controlled trial C or D 1–5 Statistics not reported or questionable, or <80% follow-up 2 B
    Non-systematic review, cohort study, case study (e.g. some adverse effect guidance) NA NA NA 3 C
    Clinical practice information (expert opinion), inconsistent evidence NA NA NA 4 D
    Allocation concealment is rated as: A, adequate; B, unclear; C, inadequate; D, not used. The grade of recommendation is based on the overall level of evidence, considering the balance of clinical practice information and evidence. NA: not applicable
  • Included studies are stratified by timing of the intervention (pre-operative, intra-operative or postoperative), and further categorised into the type of intervention: analgesic (systemic analgesics, analgesic adjuncts or regional analgesia techniques), anaesthetic or surgical.
  • Summary information from the included studies is extracted and tabulated using a predefined data extraction form.
  • Extracted information includes: study design (including interventions); population characteristics; outcomes assessed (e.g. pain scores, supplementary analgesic use, adverse events); and critical evaluation (e.g. relevance to current clinical practice, and use of paracetamol and non-steroidal anti-inflammatory drugs or COX-2 specific inhibitors [termed as ‘basic analgesic regimen’] in the study groups).
  • Primary outcomes are: postoperative pain intensity scores at rest and/or pain intensity during activity (when available). A change of more than 10 mm in pain scores is considered clinically relevant.
  • Secondary outcomes include: time to first request for rescue analgesia; cumulative 24-h opioid requirements; other supplementary analgesic use; opioid-related adverse events; and patient-related outcome measures.
  • The effectiveness of each intervention for each outcome is evaluated qualitatively by assessing the number of studies showing a significant difference between treatment arms (p<0.05 as reported in the study publication).
  • Meta-analyses are performed if the studies are homogenous in the analgesic technique(s) utilised, with similar outcome measures that are reported or can be estimated as mean (SD) for continuous variables and proportions for dichotomous variables.