Is a Placebo Just as Effective as Morphine in Treating Rheumatoid Arthritis Pain?

The morphine seemed to only help with pressure pain threshold, which also apparently was helped by placebo too.

The study group measured pain in many different ways. First, they marked perceived pain threshold at the muscles of the shoulder blade and thigh. These are common places for pain in patients who have rheumatoid arthritis or fibromyalgia. Next, they measured the temporal summation of pain, which is the concept that continued pressure causing pain enhanced the sensation of pain with more elapsed time. Then, deep tissue pain was also measured by using a cuff on the upper arm. This cuff was inflated until the patient felt uncomfortable. This helped investigators figure out how much deep pressure was considered tolerable to the person being evaluated. Lastly, researchers looked at conditioned pain, which was a measurement of the temporal summation after a conditioning stimulus. In this case, they used the deep tissue pain cuff as the conditioning stimulator.

The results of the study revealed that before receiving any treatment at all, all the patients with either fibromyalgia or rheumatoid arthritis had deep tissue pain at lower pressure and higher temporal summation. This translates to more painful inflated cuff test and a more enhanced pain due to temporal summation. However, the effect of morphine wasn't as positive as one might think. This means that we don't really have evidence that morphine does any better than placebo in improving pressure pain threshold. The results also found that neither morphine or placebo had any significant effects on the pain threshold, deep tissue pain, temporal summation, or conditioned pain in healthy people. The scientists explain that their findings suggest morphine's effects to be more peripheral rather than central.