저자 및 기관: 전소연·박히준·채윤병 (침구경락융합연구센터), 이향숙 (침구경락융합연구센터, Australian Research Centre in Complementary and Integrative Medicine)

발표 저널: BMC Medical Research Methodology

원문 링크:  https://pubmed.ncbi.nlm.nih.gov/29347917/

서지사항

Cheon S, Park HJ, Chae Y, Lee H. Does different information disclosure on placebo control affect blinding and trial outcomes? A case study of participant information leaflets of randomized placebo-controlled trials of acupuncture. BMC Med Res Methodol. 2018 Jan 18;18(1):13. doi: 10.1186/s12874-018-0474-1.

Abstract

Background: While full disclosure of information on placebo control in participant information leaflets (PILs) in a clinical trial is ethically required during informed consent, there have been concerning voices such complete disclosures may increase unnecessary nocebo responses, breach double-blind designs, and/or affect direction of trial outcomes. Taking an example of acupuncture studies, we aimed to examine what participants are told about placebo controls in randomized, placebo-controlled trials, and how it may affect blinding and trial outcomes.

Methods: Authors of published randomized, placebo-controlled trials of acupuncture were identified from PubMed search and invited to provide PILs for their trials. The collected PILs were subjected to content analysis and categorized based on degree of information disclosure on placebo. Blinding index (BI) as a chance-corrected measurement of blinding was calculated and its association with different information disclosure was examined. The impact of different information disclosure from PILs on primary outcomes was estimated using a random effects model.

Results: In 65 collected PILs, approximately 57% of trials fully informed the participants of placebo control, i.e. full disclosure, while the rest gave deceitful or no information on placebo, i.e. no disclosure. Placebo groups in the studies with no disclosure tended to make more opposite guesses on the type of received intervention than those with disclosure, which may reflect wishful thinking (BI -0.21 vs. -0.16; p = 0.38). In outcome analysis, studies with no disclosure significantly favored acupuncture than those with full disclosure (standardized mean difference - 0.43 vs. -0.12; p = 0.03), probably due to enhanced expectations.

Conclusions: How participants are told about placebos can be another potential factor that may influence participant blinding and study outcomes by possibly modulating patient expectation. As we have few empirical findings on this issue, future studies are needed to determine whether the present findings are relevant to other medical disciplines and at the same time a routine practice of fully disclosing placebo information in PILs calls for reevaluation.

Keywords: Blinding; Information disclosure; Informed consent; Outcome; Participant information leaflet; Placebo; Randomized controlled trial.

한글 요약

플라시보 대조군 (거짓침)을 이용한 침 무작위배정 비교시험의 사전동의서/설명서를 내용 분석한 결과 거짓침에 관한 정보를 실제로 어떻게 제공하고 있는지에 대하여 세계 각국에서 수행된 임상시험의 설명서 65편을 교신저자로부터 실제로 입수하여 양적-질적으로 분석하여 보았다. 그 결과 거짓침 정보를 완전히 제공하지 않거나 부분적으로 혹은 완전하지 못한 형태로 제공하는 경우들도 드물지 않았다. 또한 정보를 부분적으로 제공하거나 완전하지 못한 형태로 제공하는 경우 환자 눈가림이 잘 되는 경향이 있으며 연구 결과도 더 효과가 있게 나타나는 경향성이 (통계적으로 유의하지는 않은 정도로) 나타났다. 

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