For clinical effectiveness, 16 studies (overall n=not clear) were included in the review: two RCTs; one retrospective cohort study; and 13 case series. The RCTs were considered to be of moderate quality; all other studies were of low quality.
Pain reduction (two RCTs, 13 case series): Spinal cord stimulation treatment resulted in significant improvements in pain reduction compared to the control treatment (two RCTs). In one RCT, number needed to treat was three (95% CI 2 to 7) for at least 50% pain relief in the leg. In another RCT, number needed to treat was four (95% CI 3 to 47). All 13 case series demonstrated success or very good to good pain relief with spinal cord stimulation treatment (statistical results reported in only one study).
Quality of life (one RCT, three case series: There were significant improvements in quality of life in seven of eight domains of SF-36 after six months follow up in participants treated with spinal cord stimulation compared to controls (one RCT), p values varied from 0.01 to <0.001. Significant improvements in quality of life with spinal cord stimulation treatment were also reported in three case series.
Activities of daily living (one RCT, one retrospective cohort, seven case series): One RCT demonstrated no significant differences between treatment groups in the percentage of patients who returned to work. All other studies reported improvements in activities of daily living with spinal cord stimulation treatment (statistical results reported in only one study).
Functional status (one RCT, one retrospective cohort, two case series): The RCT reported significant improvements in functional status with spinal cord stimulation treatment after six months follow up (p<0.001). Significant improvements were reported in the other studies.
Depression (one case series): A significant improvement in depression was reported after one year follow up.
Drug use (one RCT, one retrospective cohort, five case series): There were no significant differences between the treatment and comparison groups in opioids use and in percentages of participants who used opioids, nonsteroidal anti-inflammatory drugs, antidepressants and anticonvulsants after six months (one RCT). Results from the other studies varied.
Patient satisfaction (two RCTs, one retrospective cohort, three case series): Both RCTs reported significantly improved patients satisfaction with spinal cord stimulation treatment after six months follow up. The other studies reported that 60% or more patients were satisfied with spinal cord stimulation treatment after more than three years follow up.
Adverse events: Any infection, mean 5% (range 2% to 14%; 13 studies); infection that required removal of the device, mean 3% (range 1% to 8%; nine studies); pain along the lead or pulse generator, mean 12% (range 2% to 23%; six studies); other event, mean 11% (range 3% to 18%; seven studies); hardware failure, mean 28% (range 2% to 71%; 10 studies).