Mini-Review on Placebo and Nocebo effects

Abstract background: Placebo and nocebo effects have a great impact on the medical field. However, the complexity and narratives of this subject have obscured basic concepts. There is a conflict in definitions, causal relations and other factors that create confusion in the field. Furthermore, interest and output of research have risen on this subject. The aim of this research is to create an introduction for students and physicians with no prior experience in the field.

Methodology: A systematic review of placebo and nocebo effects was carried out. Keywords "placebo", "nocebo", "effect" and "review" were searched on 3 databases and indexed journals (Pubmed, The Lancet, The New England Journal of Medicine). Not available articles were searched using the CRAI directory of Universidad del Quindío. The results were restricted to the last 25 years.

The article has been organized upon PRISMA guidelines. Data extraction and management was carried out using a method created by Burns and Grove and later expanded by Guirao-Goris et al.

Results: 349 articles were found using these restrictions. 98 articles were filtered after screening. At the evaluation stage, 112 articles were excluded depending on rigour and quality. At the synthesis stage 29 articles were excluded due to overlapping data. 127 articles were used on the final manuscript.