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Reporting of key methodological issues in placebo-controlled trials of surgery needs improvement: a systematic review

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)109-116
Number of pages8
JournalJournal of Clinical Epidemiology
Early online date28 Nov 2019
DateAccepted/In press - 24 Nov 2019
DateE-pub ahead of print - 28 Nov 2019
DatePublished (current) - 1 Mar 2020


To examine key methodological considerations for using a placebo intervention in randomised controlled trials (RCTs) evaluating invasive procedures, including surgery.

Study design and setting
RCTs comparing an invasive procedure with a placebo were included in this systematic review. Articles published from database inception to 31st December 2017 were retrieved from Ovid MEDLINE, Ovid EMBASE and CENTRAL electronic databases, hand searching references and expert knowledge. Data on trial characteristics (clinical area, nature of invasive procedure, number of patients and centres) and - i) rationale for using placebos; ii) minimisation of risk; iii) information provision; iv) offering the treatment intervention to patients randomised to placebo; v) delivery of co-interventions; vi) intervention standardisation and fidelity were extracted and summarised descriptively.

Identified were 113 articles reporting 96 RCTs. Most were conducted in gastrointestinal surgery (n=40, 42%) and evaluated minimally invasive procedures (n=44, 46%). Over two thirds randomised fewer than 100 patients (n=65, 68%) and a third were single centre (n=31, 32%). A third (n=33, 34%) did not report a rationale for using a placebo. Most common strategies to minimise patient risk were operator skill (n=22, 23%) and independent data monitoring (n=28, 29%). Provision of patient information regarding placebo use was infrequently reported (n=11, 11%). Treatment interventions were offered to patients randomised to placebo in 43 trials (45%). Co-interventions were inconsistently reported, but 64 trials (67%) stated that anaesthesia was matched between groups. Attempts to standardise interventions and monitor their delivery were reported in n=7, (7%) and n=4, (4%) trials, respectively.

Most placebo-controlled trials in surgery evaluate minor surgical procedures and currently there is inconsistent reporting of key trial methods. There is a need for guidance to optimise the transparency of trial reporting in this area.

    Structured keywords

  • Bristol Population Health Science Institute

    Research areas

  • Surgery, placebo surgery, invasive procedures, systematic review, methodology

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