Dichotomous outcome measures are important in synthesising information from many studies, and in deriving NNTs. In chronic pain, there is evidence that TENS effectiveness increases slowly, and that large doses need to be used. There is lack of evidence for the effectiveness of TENS in chronic pain. There is a lack of evidence for the effectiveness of relaxation. Intravenous systemic regional blockade with guanethidine has been shown to be without effect.
Epidural corticosteroids are effective in the short term for back pain and sciatica.
Injections of corticosteroids in or around shoulder joints for shoulder pain have been shown not to be effective. There is a lack of evidence supporting spinal cord stimulators. Minor analgesics are important in chronic pain. NNTs were calculated for analgesics given orally for moderate or severe acute postoperative pain. Anticonvulsant and antidepressant drugs are prescribed for neuropathic pains like diabetic neuropathy.