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Aunque por otra parte es difícil de controlar el sesgo por indicación de los estudios que reportan la asociación entre anemia y desenlaces adversos en pacientes que requieren ser transfundidos, es importante resaltar la importante cantidad de estudios que asocian la transfusión con el aumento de los desenlaces adversos, como neumonía, mediastinitis, disfunción renal, mortalidad y disminución de la supervivencia.