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document such as ‘neuropathic’, ‘patient‐controlled’, ‘epidural’, ‘paracetamol’ and so on. For
drugs and techniques a search was also made for ‘efficacy’ and ‘complications’. Hand searches
were also conducted of a large range of relevant journals from 2005 onwards and
bibliographies of relevant papers were checked.
Preferred evidence
A review of acute pain management requires a broad focus on a range of topics (eg
postoperative pain, musculoskeletal pain, migraine, pain associated with spinal cord injury
etc). This broad focus inevitably produces a very large number of research publications. In
order to provide the best information and to inform best practice, it was important to
concentrate on the highest ranked, highest quality evidence available.
Secondary evidence: High quality systematic reviews of randomised‐controlled trials (NHMRC
Level I) were the preferred evidence source. This approach was efficient as many high quality
systematic reviews of specific aspects of acute pain management have already been
undertaken by the Cochrane Collaboration and other reputable evidence‐synthesis groups
(such as members of the Oxford Pain Group). Systematic reviews that included non‐
randomised controlled studies were assigned the level of evidence of their component studies,
as outlined in the NHMRC designation of evidence levels (NHMRC 1999) (see below).
Primary evidence: Where Level I reviews were not available, the next preferred level of
evidence was single randomised controlled trials (NHMRC Level II). Where these were not
available, other experimental evidence or case series were accepted as the best available
evidence by the guideline developers (reflecting NHMRC Level II and Level IV). According to
NHMRC guidelines (NHMRC 1999), Level IV evidence is obtained from case series, either post‐
test or pre‐test and post‐test; the levels refer to evidence about interventions. Publications
describing results of audits or papers that were comprehensive clinical reviews, for example,
were also included as Level IV evidence.
Expert opinion: In the few instances where no relevant published evidence was available,
expert opinion was included as the best available information.
Other evidence types: Not all evidence relating to the management of acute pain is
intervention‐based. In a number of instances, best practice has been derived from record
audit, quality processes or single case reports.
Examples of evidence level decision‐making: For examples of the decisions that were made
about assigning levels to low quality evidence where there was limited evidence available, see
the table below.
Examples of decisions made assigning levels to evidence of lower quality
Systematic reviews of A systematic review looking at the benefits or otherwise of preoperative
articles including those education for orthopaedic patients highlighted the difficulties of
with the lowest level of
comparing studies of variable methodological quality (Johansson et al
APPENDIX B Level III‐2 were cited as The amount of morphine a patient requires is better predicted by their
2005)
evidence designated as
Level III‐2
Evidence from audits or
age rather than weight (adds to safety of prescribing) (Macintyre & Jarvis
case series that directly
affects patient safety
cited as Level IV 1996)
The routine use of a continuous infusion with patient‐controlled
analgesia (PCA) markedly increases the risk of respiratory depression
(Schug & Torrie 1993)
Delays in the diagnosis and treatment of an epidural abscess in a patient
466 Acute Pain Management: Scientific Evidence
