Double blinding a clinical trial (i.e., the investigator and patient) is rarely sufficient today to maintain a sufficient blind. It is also necessary in most cases of randomized controlled trials to blind the clinical monitors, the sponsor's statisticians (except for one), and the staff who are conducting special procedures (e.g., EKGs, eye exams, MRIs).

Single-blind trials are virtually equivalent to open-label trials.

Double-blind trials vary along an entire spectrum from those that are truly double- blind to those that have become totally un-blinded. It is often imprtant to determine where on that spectrum a specific trial is located. This can often be determined by questioning the investigator and patients about the treatment they believe was given and the reasons for their choice. Surprises often occur in reviewing these data.

Open-label clinical trials often mislead a company as the data obtained have a much greater likelihood of being positive than if the same trial was done in a double- blind manner. This may lead to a company wasting years of effort and millions of their money until they recognize that the drug really did not demonstrate efficay in a true double-blind study.

About 80% of open-label trials are positive whereas only 20% of double-blind trials show positive results when the exact same question is evaluated in an almost identical study.