Systematic reviews – leading or misleading?




Poster session 2 Thursday: Evidence synthesis - methods / improving conduct and reporting


Thursday 14 September 2017 - 12:30 to 14:00


All authors in correct order:

Nørgaard MW1, Bjerrum M2, Pedersen PU3
1 Cardiac Cath.lab, The HeartCentre, Rigshospitalet, Copenhagen, Denmark
2 School of Public Health, Department of Nursing Science, Aarhus University, Denmark
3 Centre of Clinical Guidelines, Health Science faculty, Department of Health Science and Technology, Aalborg University, Denmark
Presenting author and contact person

Presenting author:

Marianne Wetendorff Nørgaard

Contact person:

Abstract text
Background: Patients who undergo invasive procedures in light sedation often feel pain during the procedure. Hypnotic analgesia as an adjunct to usual analgesia to relieve such pain has been investigated in numerous trials.

Objectives: To identify appraise and synthesise the best available evidence on the effectiveness of hypnotic analgesia in the management of procedural pain in adults undergoing minimally invasive procedures.

Methods: Randomised-controlled trials and quasi-experimental before and after studies, where hypnotic analgesia was used as an adjunct and compared to usual pharmacological analgesic were included in this systematic review. Outcomes were patient-rated pain, - pain intensity, -anxiety, amount of pain medication used; procedure-length and adverse events.
Two independent reviewers used the standard appraisal tools from the Joanna Briggs Institute to assess the methodological quality of the studies and data extraction.
Results: Nine randomised-controlled trials and 1 quasi-experimental study with 1365 patients were included. No significant difference in pain intensity and anxiety was found. In 5 out of 5 studies a reduction of pain medication was reported even if patients did not report lower pain intensity.

Discussion/Conclusion: The quantitative results of this systematic review did not report clear evidence of the feasibility of hypnotic analgesia and a significant reduction in pain intensity. However, findings from qualitative studies show that patients do experience pain but use hypnosis as a strategy to manage the pain. In the included studies, pain intensity was measured by using conventional instruments developed to measure pain intensity in trials, to assess the effectiveness of analgesics, which is fundamentally different from patient’s management of pain.
From a methodological point of view, it is most relevant to discuss the risk of bias by doing systematic reviews that do not consider this type of problem, as they might miss and not recognise the effect of an effective intervention, because studies included have measured patient-related outcomes with instruments that do not capture the true essence of the phenomenon.