When it comes to testing new drug treatments, placebos are the defacto way to measure their effectiveness. If the treatment has better outcomes than the placebo scientists know they are on the right track.
But new research out of the University of Oxford pours cold water on that longstanding thesis.
Turns out olive oil is not a great placebo
Researchers including Jeremy Howick, director of Oxford Empath Programme said there are fundamental problems with considering placebos the gold standard because they have different effects, leading in some cases to mistaken inferences about the effectiveness and harm from new drugs.
The researchers pointed to olive oil as an example. In the past, it has been used as a placebo for testing drugs that lower cholesterol. That was before it was discovered that olive oil has its own cholesterol-lowering properties which may have explained why the results of trials of oseltamivir (Tamiflu) had lower than anticipated drug effects.
When reporting whether or not Tamiflu causes gastrointestinal symptoms, the researchers compared it to the olive oil placebo. The researchers said using olive oil to compare the side effects had the potential to underestimate the true number of gastrointestinal symptoms present in oseltamivir.
"It is impossible to say how often placebo components influence what the apparent benefit of the new treatment is until such components are reported adequately. As this study shows, they rarely are," co-lead author, Dr. Rebecca Webster, from the University of Oxford said in a press release highlighting the results.
Placebo controls need to be improved
According to the researchers as it stands placebo controls are poorly described in randomized trials with very few using the 12-item Template for Intervention Description and Replication checklist, which was created to improve trial reporting. The researchers recommended the development of guidelines to create better descriptions of the placebo control within clinical trials.
"The idea that we need to report what’s in a placebo seems like overkill to many people because they mistakenly believe that placebos are inert, or white noise," added Howick.