Diferencias entre las características basales de los pacientes en los ensayos clínicos, según el tamaño de la muestra. Un estudio metaepidemiológico

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Daniel Vanegas Isaza
  • Biografía

    Estudiante de Medicina, Facultad de Medicina, Universidad Pontificia Bolivariana. Medellín, Colombia.

Mateo Zuluaga Gómez
  • Biografía

    Estudiante de Medicina, Facultad de Medicina, Universidad Pontificia Bolivariana. Medellín, Colombia.

Jorge Hernando Donado Gómez
  • Biografía

    Médico internista y epidemiólogo, Hospital Pablo Tobón Uribe. Profesor, Universidad Pontificia Bolivariana. Medellín, Colombia


Objetivo: determinar las diferencias en las variables cualitativas y cuantitativas de las características basales de los ensayos clínicos controlados con asignación aleatoria, según su tamaño de muestra.

Metodología: estudio observacional, transversal que incluyó los ensayos clínicos con asignación aleatoria publicados en cuatro revistas médicas generales de alto factor de impacto. Según su tamaño de muestra, se dividieron en cinco estratos y se evaluó la diferencia entre variables cualitativas y cuantitativas de las características basales.

Resultados: se analizaron 1000 variables de los pacientes que participaron en ensayos clínicos. Cuando se comparó cada uno de los grupos por tamaño de muestra con respecto al de ≥5000 pacientes, se encontró que las diferencias de medias disminuían a medida que los tamaños de muestra tenían mayor número de pacientes.

Conclusiones: la diferencia de resultados de las características basales de los ensayos clínicos, es inversamente proporcional al tamaño de muestra y, por encima de 500 pacientes por grupo, las diferencias promedio serían menores al 1.2%.

Palabras clave:
clinical trial, sample size, random allocation ensayo clínico, tamaño de la muestra, distribución aleatoria ensaio clínico, tamanho da amostra, distribuição aleatória

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