These days we often hear about how a new treatment, or program, or therapy style, is "evidence based." This gives the listener an impression that the new treatment must be superior in some way.
It is another language construct which has become much more common, especially in mental health care discussions. Recently, its prevalence has tripled in written language, with a steep increase beginning in about 1993, according to the Google NGram viewer.
But was does "evidence based" really mean?
We often hear, for example, that cognitive-behavioural therapy (CBT) is "evidence based." The implication of this statement is that other forms of therapy must not be "evidence based."
It should go without saying that most everything is "evidence based":
An individual's personal account of their experience is a form of evidence.
A randomized controlled prospective trial of therapy supplies another form of evidence.
An opinion from an expert, or from a mystic, or from a random person on a bus, or from a charlatan, is another form of evidence.
the introduction of the phrase "evidence based" may stifle
debate and free thinking about a matter. It implies that the issue it is describing
has already been decided upon.
In psychiatry, the phrase "evidence based" is typically used in the area of CBT research, and in health care policy. But this can bias opinion away from other therapeutic modalities whose practitioners tend not to advertise themselves with this type of language.
I believe that gathering evidence from prospective, randomized, controlled clinical studies is vitally important--so important, in fact, that we must allow such evidence to cause established opinions about care to actually change. There are many cautionary tales in medical history, in which good evidence about something new was dismissed by practitioners who were resistant to changing the style of practice they had grown up with.
But in mental health care, the evolving evidence is often much less robust than it seems. Most studies are of very short duration. Short-term or superficial care approaches may lead to various symptomatic improvements for many people...but long-term data is often not present. Also, a great deal of evidence supports the efficiency of treatments which work for 60-70% of people, but does not support useful options of how to help the other 30-40%.
Many people may look back and value a short-term course of therapy in some way, but what they really found most valuable and life-changing was something quite different, such as having a dedicated caregiver over a period of many years who didn't practice using modern "evidence-based" methods at all...
It is good to think carefully about evidence, and to be prepared to change our practice accordingly. But the phrase "evidence based" is often just a slogan, a form of jargon, and a construct which can lead to unwelcome biases in thinking. Such cognitive short-cuts can often be very efficient, in order to decide on an important matter quickly, but such short-cuts should never be used to make large policy changes in a system.