Cancer Pain With a Neuropathic Component: A Cross-sectional Study of Its Clinical Characteristics, Associated Psychological Distress, Treatments, and Predictors at Referral to a Cancer Pain Clinic

In patients with cancer pain, identifying a neuropathic pain component (NPC) may inform the selection of subsequent therapeutic interventions. The objective of this study was to determine the prevalence, clinical characteristics, associated psychological distress, pre-referral treatment, and predictors of cancer pain with an NPC in patients referred to a cancer pain clinic. Participants had standard assessments and documentation: Brief Pain Inventory ratings, presence of an NPC, based on a Douleur Neuropathique 4 (DN4) (neuropathic pain screening scale) score ≥4 combined with a physician's clinical assessment (blinded to DN4 result), the Hospital Anxiety Depression Scale, and Emotion Thermometer scores. Logistic regression analyses were used to determine predictors associated with an NPC. Of 371 study participants, 120 (32.3%) had a designated NPC. Overall, psychological distress indices were similar in the NPC and nociceptive pain groups, except for a Hospital Anxiety and Depression Scale >7 score that was proportionately higher (74% vs. 63%, P = 0.03) in the nociceptive group. The final multivariable logistic regression model generated the following NPC predictors and their respective odds ratios (95% CIs): recent chemotherapy, 2.93 (1.63–5.26); recent surgery, 3.65 (2.03–6.59); adjuvant analgesic use, 2.93 (1.66–5.17); episodic incident pain, 2.63 (1.44–4.84); episodic breakthrough pain, 3.67 (2.00–6.73); pain duration three or more months, 2.35 (1.36–4.06); higher pain intensity, 1.47 (1.24–1.74); and pelvic or perineal pain location, 2.75 (1.09–6.96). One in three patients with cancer have an NPC, which is independently associated with recent chemotherapy, surgery, adjuvant analgesic use, episodic incident and breakthrough pain, longer pain duration, higher pain intensity, and pelvic or perineal pain location.