Predicting Satisfaction from TENS Depends on Outcome Measure

TENS, transcutaneous electrical nerve stimulation, is an increasingly popular non-medication pain treatment, but there has not yet been any definitive studies regarding its effect on chronic pain.

There are several causes of chronic pain, but the two mechanisms are muscle and joint tissue pain and nerve pain. The authors of this study examined the effects of TENS and if researchers could predict if high intensity TENS would be successful in patients with chronic pain.

Researchers recruited 163 subjects who had chronic noncancer pain. These subjects were divided into three groups, those with:

- osteoarthritis, osteoporosis, bursitis, or tendonitis
- peripheral neuropathic pain, nerve pain
- bone, soft tissue, and visceral (organs in the body) pain

The subjects were then randomized to receive either high intensity TENS or a sham treatment that looked identical to the TENS. They received 10 days of treatment and were assessed before and after the 10-day period.

The researchers evaluated whether the patients were satisfied with the TENS treatment and the pain intensity before and after. Pain levels were measured using a Visual Analog Scale (VAS), a scale from zero to 10, with zero being no pain and 10 being the most severe pain possible.

Disability from the pain was measured using the Pain Disability Index (PDI), also a scale from zero to 10, with zero being no disability and 10 being total disability. Pain coping was measured with the Pain Coping Inventory (PCI), while pain cognition was measured with the Pain Cognition List. Finally, depression was measured with the Beck Depression Inventory (BDI).

The results showed the subject satisfaction varied significantly in the TENS group compared with the sham group, but no significant differences were seen in pain intensity between the two groups. Fifty-eight percent of the TENS group and 42 percent of the sham group were satisfied with the treatment result. Those who had injuries to the bone or soft tissues were the most satisfied.

The authors wrote that predicting the effect of the treatment depended on what the researchers were looking for. For example, they expected osteoarthritis to have better results than they actually did.



References: Jan Oosterhof, et al. Predicting Outcome of TENS in chronic pain: A prospective, randomized, placebo controlled trial. In Pain. May 2008. Vol. 136. No. 1-2. Pp. 11-20