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The Medtronic (MDT) PROCESS Study is the first randomized, controlled, multicenter trial comparing the effectiveness of spinal cord stimulation (SCS) plus conventional medical management (CMM) versus CMM alone.
24 (48%) patients achieved the primary outcome of ≥ 50% leg pain relief as compared to 4 (9%) patients in the CMM alone group (p < 0.001).
NOTE: With the VAS, patients rate level of pain on a scale from 0 (no pain) to 10 (worst possible pain); the scores are then graded and given a percentage score.
In an as treated analysis2, 34 (47%) patients who received MDT SCS+CMM achieved the primary outcome versus 1 (7%) who received CMM along (p = 0.02).
In a modified ITT analysis2, 17 (37%) patients randomized to MDT SCS+CMM and 1 (2%) randomized to CMM alone achieved the primary outcome of ≥ 50% leg pain relief (p = 0.003).
NOTE: An ITT analysis compares all data from patients in the groups to which they were randomized. The modified ITT means that for all patients who requested to cross over; at 6 months, they were considered to have < 50% pain relief. An as treated analysis compares the groups based on the treatment the patient is receiving at the time of the visit.
Compared to baseline, the 42 patients continuing MDT SCS+CMM experienced statistically significantly lower levels of leg pain (P < 0.0001).
69% of the 42 MDT SCS+CMM patients continuing therapy achieved (≥ 30%) leg pain relief.3
NOTE: A 30% reduction in pain is clinically meaningful.4
MDT SCS+CMM patients experienced superior function on the ODI compared with CMM patients (p < 0.001).
Compared to baseline, the 42 patients continuing MDT SCS+CMM experienced statistically significant improvement in functional capacity (p = 0.0002).
NOTE: The ODI score is produced from patient-completed questionnaires that include six statements in each of 10 sections concerning impairments like pain and abilities such as personal care, lifting, reading, driving, and recreation. The scale is interpreted as: 0%-20% (minimal disability); 20%-40% (moderate disability); 40%-60% (severe disability); 60%-80% (severely disabled in several areas of life/crippled); 80%-100% (bed bound or exaggerating symptoms).5
Of the 42 patients continuing SCS+CMM at 24 months, 23 patients (55%) did not experience any SCS-related complications, and 19 patients experienced a total of 34 SCS-related complications. For 13 patients, a surgical revision was required to resolve the event.
Kumar K, Taylor RS, Jacques L et al. Spinal cord stimulation versus conventional medical management for neuropathic pain: a multicentre randomised controlled trial in patients with failed back surgery syndrome. Pain 2007;132:179-188.
Kumar, et. al. The effects of spinal cord stimulation in neuropathic pain are sustained: a 24-month follow-up of the prospective randomized controlled multicenter trial of the effectiveness of spinal cord stimulation. Neurosurgery. 2008;63(4)762-770.
Cruccu G, Anand P, Attal N, et al. EFNS guidelines on neuropathic pain assessment. Eur J Neurol. 2004;11:153-162.
Teng J, Mekhail N. Neuropathic pain: mechanisms and treatment options. Pain Practice. 2003;3(1):8-21.
Fairbank JC, Couper J, Davies JB, O’Brien JP. The Oswestry low back pain disability questionnaire. Physiotherapy. 1980;66(8):271-273.