Inadequate description of placebo and sham controls in a systematic review of recent trials

Abstract

Background Poorly described placebo/sham controls make it difficult to appraise active intervention benefits and harms. The 12‐item Template for Intervention Description and Replication (TIDieR) checklist was developed to improve the reporting of active interventions. The extent to which TIDieR has been used to improve description of placebo or sham control is not known. Materials and methods We systematically identified and examined all placebo/sham‐controlled randomised trials published in 2018 in the top six general medical journals. We reported how many of the TIDieR checklist items were used to describe the placebo/sham control(s). We supplemented this with a sample of 100 placebo/sham‐controlled trials from any journal and searched Google Scholar to identify placebo/sham‐controlled trials citing TIDieR. Results We identified 94 placebo/sham‐controlled trials published in the top journals in 2018. None reported using TIDieR, and none reported placebo or sham components completely. On average eight TIDieR items were addressed, with placebo/sham control name (100%) and when and how much was administered (97.9%) most commonly reported. Some items (rationale, 8.5%, whether there were modifications, 25.5%) were less often reported. In our sample of less well‐cited journals, reporting was poorer (average of six items) and followed a similar pattern. Since TIDieR’s first publication, six placebo‐controlled trials have cited it according to Google Scholar. Two of these used the checklist to describe placebo controls; neither one completely desribed the placebo intervention. Conclusions Placebo and sham controls are poorly described within randomised trials, and TIDieR is rarely used to guide these descriptions. We recommend developing guidelines to promote better descriptions of placebo/sham control components within clinical trials.

A meta-research study revealed several challenges in obtaining placebos for investigator-initiated drug trials

“…This was usually not reported in the published article, or even worse, were misclassified as matching. Inadequate reporting of placebo controls was also found by Webster and colleagues, although not focusing on the reporting of matching [16].…”

Intervention reporting of clinical trials published in high-impact cardiology journals: effect of the TIDieR checklist and guide

“…These findings are comparable to recent studies evaluating intervention reporting. For example, Webster et al recently found that, on average, only 8 out of 12 TIDieR items were reported in placebo and sham-controlled trials published in the top six general medical journals 22. Another study found only 8.8/12 TIDieR items reported for poststroke exercise programme interventions 23…”

TIDieR-Placebo: A guide and checklist for reporting placebo and sham controls

“…JH, TH, and RKW conducted preliminary research exploring the need to describe placebo and sham components adequately [2,3,19]. JH drafted and registered the protocol [20].…”

“…To address intervention reporting, the Template for Intervention Description and Replication (TIDieR) checklist was developed to aid reporting of interventions and can be used in conjunction with CONSORT. However, neither CONSORT nor TIDieR explicitly mention placebo or sham controls, and our background research revealed that they require some modification to guide adequate reporting of these interventions [3].…”

“…A 2010 systematic review found that between 8.2% (pharmacological) and 26.7% (nonpharmacological) trials adequately described placebo or sham interventions [2]. Ten years later, things have barely improved [3]. Hence, the need to look more closely at what placebo or sham comparators are is becoming more widely recognised [4].…”