Efecto placebo en la medicina contemporánea

Lázaro Gómez Fernández

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Objetivo: Explicar el concepto de placebo y efecto placebo, así como otros procesos vinculados con la respuesta terapéutica.

Adquisición de la evidencia: Se realizó una búsqueda bibliográfica en las bases de datos PubMed, Scopus y EMBASE hasta mayo 2020. Se utilizaron las palabras clave: “placebo”, “placebo effect”, “placebo response”, “placebo intervention”. Se seleccionaron 107 artículos en idioma inglés y español: revisión (35), ensayos clínicos (26), metaanálisis y revisiones sistemáticas (10), que abordaban aspectos metodológicos sobre el uso y el efecto del placebo. Se excluyeron 36 artículos por presentar diversos errores metodológicos.

Resultados: El efecto placebo está presente en intervenciones farmacológicas y no farmacológicas. En él influyen la expectativa del paciente, mecanismos de condicionamiento pavloviano, el aprendizaje y las características del tratamiento. El uso de placebos puede ser responsable de una mejoría de hasta un 60% de los síntomas en los enfermos. Existen también otros procesos que modulan la respuesta al tratamiento, como la observación (Hawthorne), la regresión a la media, la evolución natural de la enfermedad y el efecto Pygmalion. El desarrollo de ensayos clínicos bien diseñados es la clave para avalar la introducción exitosa de nuevos tratamientos.

Conclusiones: El placebo es cualquier sustancia o intervención inerte, utilizada con intención curativa. El efecto placebo consiste en la mejoría de los síntomas que resulta del uso de un placebo. La observación experimental, la regresión a la media y la evolución natural de la enfermedad, son factores que influyen en la apreciación de la respuesta terapéutica.

Palabras clave

placebo; efecto placebo; respuesta placebo; intervención placebo

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