Analysis of psychological characteristics impacting spinal cord stimulation treatment outcomes: a prospective assessment

Background: Psychological factors are recognised as influencing the outcome of spinal cord stimulation (SCS) although there is currently no consensus as to which factors impact upon SCS efficacy. Objective: To identify psychological characteristics that may impact the efficacy of SCS. Study Design: Prospective evaluation. Setting: Single secondary care center in Dudley, United Kingdom. Methods: Patients: Seventy-five patients were initially recruited and 56 patients (31 women and 25 men) were followed-up for 12-months. Intervention: SCS for the management of chronic non-cancer pain. Main Outcome Measures: Outcome measures assessed at baseline, 6 months, and 12 months following SCS implantation included the visual analogue scale (VAS), Oswestry disability index (ODI), hospital anxiety and depression (HAD) scale, and the pain coping strategies questionnaire (PCSQ). Results: Statistically significant improvements were observed for the VAS (P < 0.001), ODI (P = 0.011), anxiety (P = 0.042), and depression (P = 0.010) in the HAD scale and for the subscales reinterpreting pain sensation (P = 0.018), control over pain (P = 0.001), and ability to decrease pain (P < 0.001) of the PCSQ. We observed that depression and autonomous coping (control over pain, ability to reduce pain, and catastrophizing) may impact sensory aspects such as pain intensity and disability scores affecting the outcome of SCS treatment. Age at time of implant and duration of pain prior to implant were also found to impact SCS efficacy. Limitations: It has been reported that loss of analgesia may be experienced within 12 to 24 months following SCS implantation and therefore, it would be of interest to follow patients over a longer period. Conclusions: This study demonstrates that psychological aspects such as depression and autonomous coping may impact SCS treatment. Addressing these issues prior to SCS implantation may improve SCS long-term outcome.