Background: Despite the large burden of neuropathic back pain, accurate evaluation of the condition is difficult. The Pain DETECT questionnaire (PD-Q) was developed to facilitate a clearer diagnosis of neuropathic pain. However, despite being widely used, confirmation of the implied factor model of the PD-Q has never been performed for the common condition of Low Back Pain (LBP).
Objective: To examine the factor structure of the PD-Q for patients with neuropathic low back pain using confirmatory factor analysis.
Patients and Methods: This prospective, single-centre study was conducted over a seven -month period. The PD-Q was administered to all patients who presented with low back pain at a spinal clinic in Sydney, with age greater than eighteen with nil previous lumbar spine surgery or systemic co-morbidities that would affect patient’s experience of pain.
Confirmatory factor analysis (CFA) was used to test the proposed nine item two factor-structure of the PD-Q. Recommended cut-offs for goodness-of- fit-indices were used to assess the model fit between the data and proposed the factor structure of the PD-Q.
Results: A total of 80 patients (Males: n = 43, 53.8%) with a mean age of 54.8 years (SD = 17.2) participated in the study. The median duration of symptoms was 228.5 days. The
mean pain severity was 6.9 (SD = 2.1) on an 11-point scale. The mean PD-Q score was 14.1 (SD = 7.6), with a range from 0 (Nociceptive) to 34 (Neuropathic). The goodness-of-fit (GFI) and comparative fit index (CFI) were larger than 0.9 and standardized root mean square residual (SRMR) was less than 0.08, suggesting good model fit. The overall internal consistency reliability coefficient for the PD-Q was 0.77.
Conclusion: The findings of CFA provided evidence supporting the reliability and two-factor structure of the PD-Q when evaluating neuropathic pain in a low back pain setting. Whilst a first-ever evaluation, the small sample size and selection of participants using a convenience sample gathered from only one site may limit the generalizability of findings for LBP patients.