Prospective Study of 3-Year Follow-Up of Low-Dose Intrathecal Opioids in the Management of Chronic Nonmalignant Pain

Objective. Long-term follow-up with the use of low-dose opioids in intrathecal (IT) drug delivery system (DDS) for the treatment of intractable, severe chronic nonmalignant pain. Design. This is a prospective, cohort long-term outcome study. Intervention. The intervention was the implantation of DDS. Method and patients. A total of 61 consecutive patients (60% females, 40% males) with a mean age of 59.2 years and a mean duration of symptoms prior to implant of 6.2 years were referred for implant of DDS for severe intractable noncancer pain. After adequate patient evaluation, each underwent a trial with IT opioids. Three patients failed the trial and 58 patients were implanted. Follow-up was 36 months, with intervals at 6, 12, 18, 24, and 36 months. The Brief Pain Inventory was used for follow-up assessment criteria at baseline prior to implant as well as throughout the duration of the study. Outcome Measures. Outcome measures included self-reported pain scores (worst and average), functional improvement, and IT dose, and oral opioid consumption. Results. We observed a statistically significant reduction in both worst and average pain from baseline (8.91 and 7.47 at baseline) throughout the duration of the study (4.02 and 3.41, respectively, at 36 months) (P=0.012 and P<0.001, respectively). We also documented a statistically significant improvement in physical and behavioral function. All subjects showed a significant reduction in the oral opioid consumption. The dose of IT opioids remained low and virtually unchanged for 36 months of follow-up: 1.4 morphine equivalent/day at 6 months and 1.48 at 36 months. Oral opioid averaged 128.9mg of morphine equivalent/patient/day at baseline to 3.8 at 3 month and remained at the same level throughout the study. Conclusion. Low-dose IT opioid can provide sustained significant improvement in pain and function for long-term follow-up in chronic noncancer pain.