Channeling bias in the interpretation of drug effects

Stat Med. 1991 Apr;10(4):577-81. doi: 10.1002/sim.4780100409.


Channeling is a form of allocation bias, where drugs with similar therapeutic indications are prescribed to groups of patients with prognostic differences. Claimed advantages of a new drug may channel it to patients with special pre-existing morbidity, with the consequence that disease states can be incorrectly attributed to use of the drug. For the study of adverse drug reactions, large databases supply information on co-medication and morbidity of patients. For diseases with a stepped-care approach, the drug history of patients, as available from some databases, can show channeling of drugs to patients with markers of relatively severe disease.

MeSH terms

  • Asthma / drug therapy
  • Bias
  • Clinical Pharmacy Information Systems*
  • Demography
  • Drug Therapy*
  • Drug Utilization
  • Drug-Related Side Effects and Adverse Reactions
  • Humans
  • Research Design