Publication bias perpetuates use of ineffective drugs in stroke

Drugs approved and used for treatment of stroke vary from country to country. This is, at least, partly because of variation in the standards of evidence that is required for approval of drugs across countries. For example, some countries, usually low and middle income ones, approve a drug on the basis of a small positive study or post hoc subgroup analysis in a overall negative study, while others, usually high income countries, require confirmatory or replication studies before approving the same drug. Needless to say that such confirmatory or replication studies need to be published and adequately disseminated as soon as possible so that approval decisions can be revised in the light of additional evidence. However, this does not always happen. The new evidence often remains hidden in the form of nonpublication or abbreviated publication. Sometimes, it is published but with undue delay. What is worrisome is that these problems occur more often when the new evidence does not favor the new drugs than when it favors them, a manifestation of what is called 'publication bias.' This bias is well documented in the stroke research literature (1, 2).