Comparison of pain, functioning, coping, and psychological distress in patients with chronic low back pain evaluated for spinal cord stimulator implant or behavioral pain management.

OBJECTIVE Subgroups of patients with chronic low back pain may exhibit differences in self-reported measures of pain, functioning, coping, and psychological distress. The present study compared subgroups of patients with chronic low back pain referred either for pre-spinal cord stimulator (SCS) psychological evaluations or for behavioral pain management (BPM). DESIGN Measures from comprehensive pain, functioning, and psychological assessments were compared using multivariate ancova. SETTING Tertiary care medical outpatient pain management center. SUBJECTS One hundred and two patients (64% female, mean age = 53.7, standard deviation = 14.3) with chronic low back pain diagnoses were evaluated either as possible candidates for SCS (N = 73) or as part of treatment planning for BPM (N = 29). METHODS These groups were compared on measures of pain, interference, disability, pain-related anxiety, pain coping, pain catastrophizing, depression, post-traumatic stress symptoms, affective distress, and interpersonal distress assessed using standardized scales. It was hypothesized that the two groups would report similar levels of pain, functioning, and coping, but pre-SCS patients would report fewer psychological symptoms of psychological distress compared with BPM patients in order to gain approval for SCS. RESULTS Consistent with hypotheses, BPM and pre-SCS patients reported similar pain, functioning, and coping, but pre-SCS patients reported fewer psychological symptoms. CONCLUSIONS Pre-SCS patients possibly underreport psychological symptoms perhaps to gain SCS approval for SCS. Separate norms and cutoffs for pre-SCS psychological evaluations may be needed to better identify risks of unsuccessful outcomes. Validity scales for measures of psychological distress also could be developed to detect biased reporting. Alternatively, referring clinicians may have referred patients for BPM who were more psychologically distressed and perceived as more in need of psychosocial intervention than those referred for pre-SCS evaluations. Further investigation of clinical referral decisions and assessment bias is warranted to clarify the meaning of these differences and how they apply to patient outcomes.