Making moral decisions on a double-blinded drug trial in progress without breaking the code: a primer on posterior analysis.

The double blinding of drug trials to prevent bias deprives physicians of information they need in order to comply with their duty to treat patients and do them no harm. This ethical dilemma can be ameliorated with a standard statistical method known as posterior analysis. The clinical researcher can use posterior analysis to calculate the probability that a patient in a double-blinded drug trial is in the placebo group, based on the patient's clinical status. The clinician can also calculate the probability that the drug is safe and efficacious, as compared with the placebo, without breaking the code.