​London, Oct 15 (IANS) Patients who knowingly took a placebo in combination with traditional treatment for chronic lower back pain had a significant reduction in pain and disability, a study has found.

Conventional medical wisdom has long held that placebo effects depend on patients' belief they are getting pharmacologically active medication, the study said. 

"Our findings demonstrate the placebo effect can be elicited without deception," said lead author Claudia Carvalho from Instituto Superior de Psicologia Aplicada (ISPA) in Lisbon, Portugal. 

For the study, they examined 97 patients with chronic lower back pain (cLBP), which causes more disability than any other medical condition worldwide. 

The researchers gave all patients a 15-minute explanation of the placebo effect. 

The group was then randomised into one of two groups; the treatment-as-usual (TAU) group or the open-label placebo (OLP) group.

The vast majority of participants in both groups (between 85 and 88 per cent) were already taking medications -- mostly non-steroidal anti-inflammatories (NSAIDS) -- for their pain. 

Participants in both the TAU and OLP groups were allowed to continue taking these drugs.

At the end of their three-week course of pills, the OLP group overall reported 30 per cent reductions in both usual pain and maximum pain, compared to 9 per cent and 16 per cent reductions, respectively, for the TAU group. 

The group taking placebo pills also saw a 29 per cent drop in pain-related disability. Those receiving treatment as usual saw almost no improvement by that measure.

"This new research demonstrates that the placebo effect is not necessarily elicited by patients' conscious expectation that they are getting an active medicine, as long thought," explained Ted Kaptchuk, Associate Professor at the Harvard Medical School in Massachusetts. 

Although, one can never shrink a tumour or unclog an artery with placebo intervention, but it can make people feel better, the researchers observed, adding that the placebo intervention cannot be trashed. 

"It has clinical meaning, it's statically significant, and it relieves patients. It's essential to what medicine means," Kaptchuk said, in the paper published in the journal Pain.