If the studies I read are correct, this indicates the disease they are trying to cure with this particular drug usually goes away on its own. The "placebo effect" is not getting stronger. They happen to be treating a disease in a group of people where nature usually does a better job than medical science does.
There are several diseases and syndromes that used to be treated aggressively but nowadays are often left alone because they usually go away after a while, or they cause no serious harm. Then there are diseases where some doctors recommend treatment and others do not, such as childhood hemangioma. - Jed
