Wet cupping is a therapy traditionally used in several cultures. It involves superficial injuries to the skin and subsequently the application of a vacuum cup over the injured site. This procedure would draw a small amount of blood into the cup, and this visible effect was taken as a sign that the humors or life forces or whatever are being restored.
The treatment is obviously painful and carries the risk of infection. But does it work? There are not many clinical trials of this form of alternative medicine, and I was therefore thrilled to find a new paper with a randomised clinical trial.
The aim of this clinical trial was to evaluate the effectiveness and safety of wet cupping therapy as the sole treatment for persistent nonspecific low back pain (PNSLBP). The investigators recruited 80 with PNSLBP lasting at least 3 months and randomly allocated them to an intervention group (n=40) or to a control group (n=40). The experimental group had 6 wet cupping sessions within 2 weeks, each of which were done at two bladder meridian (BL) acupuncture points. The control group had no such treatments. Acetaminophen was allowed as a rescue treatment in both groups. The Numeric Rating Scale (NRS), McGill Present Pain Intensity (PPI), and Oswestry Disability Questionnaire (ODQ) were used as outcome measures. Numbers of acetaminophen tablets taken were compared at 4 weeks from baseline. Adverse events were recorded.
At the end of the intervention, statistically significant differences in all three outcome measures favouring the wet cupping group compared with the control group were seen. These improvements continued for another two weeks after the end of the intervention. Acetaminophen was used less in the wet cupping group, but this difference was not statistically significant. No adverse events were reported.
The authors concluded that wet cupping is potentially effective in reducing pain and improving disability associated with PNSLBP at least for 2 weeks after the end of the wet cupping period. Placebo-controlled trials are needed.
Every now and then – well, actually in alternative medicine this is not so rare an event – I come across a study that ‘smells to high heaven’. This one certainly does; to be precise, it has the stench of TOO GOOD TO BE TRUE.
Apart from the numerous weaknesses of the study design, there is the fact that the results are do simply not seem plausible. Low back pain has a natural history that is well-studied. We therefore know that the majority of cases do get better fairly quickly regardless of whether we treat them or not. In this study, the control group did not improve at all, as shown on the impressive graph below (the grey line depicts the symptoms in the control group and the black one those of the cupping group).
To me, the improvement of the experimental group looks much like one might expect from the natural history of back pain. If this were true, the effect of wet cupping would by close to zero and the conclusion drawn by the authors of this trial would be false-positive.
But why was there no improvement in the control group?
I do not know the answer to this question. All I know is that it is this unexplained phenomenon which has created the impression of effectiveness of wet cupping.