Clinical realities and economic considerations: patient selection in intrathecal therapy.

Chronic nonmalignant pain, persisting more than 6 months, affects 15%-30% of the United States population. The majority of chronic pain patients respond to a combination of physical modalities and non-opioid analgesics. However, approximately 20% do not derive sufficient pain relief from traditional measures (back surgery, oral drugs, etc.). An additional percentage of patients do not achieve a favorable balance between analgesia and side effects with systemic opioid therapy. For these patients, intraspinal delivery of opioids may improve pain relief, reduce suffering, and enhance quality of life and functional ability. Patient selection is a significant determinant of the success of this approach. Because pain is a biopsychosocial phenomenon, psychological and social assessment are essential along with adequate trials of opioid responsiveness. There are several valid approaches to conducting trials of intraspinal pain therapy including epidural and intrathecal trials. Other important issues concern trial length, the utility of placebo trials, and drug selection in cases where morphine alone provides insufficient analgesia.