Epidemiology of physician-diagnosed neuropathic pain in Brazil

OBJECTIVES: Estimate the prevalence of neuropathic pain (NeP) among chronic pain patients attending Brazilian hospitals and pain clinics in São Paulo, Ceara, and Bahia and explore clinical characteristics by subtypes: painful diabetic peripheral neuropathy (pDPN), central neuropathic pain (CNP), chronic low back pain with a neuropathic component (CLBP-NeP), postherpetic neuralgia (PHN), post-traumatic neuropathic pain (PTN), and post-surgical neuropathic pain (PSN). METHODS: Physicians screened patients reporting chronic pain for ≥3 months (n=2,118) for probable NeP, using the Douleur Neuropathique 4 questionnaire and physician assessment, and reported their NeP subtype(s), symptoms, and medications. Identified NeP patients completed a questionnaire including treatment experiences, quality of life EuroQol 5 Dimensions [EQ-5D]), pain severity and interference (Brief Pain Inventory [BPI]), and Work Productivity and Activity Impairment scales. Descriptive analyses were performed by NeP subtype. RESULTS: The prevalence of probable NeP was 14.5% (n=307). NeP patients were mostly female (80.5%), middle-aged (mean [M]=52.5, SD=13.9), and Pardo (44.3%). Of those diagnosed with an NeP subtype (n=209), the largest proportions were CLBP-NeP (36.8%), followed by pDPN (18.7%), CNP (17.7%), PTN (17.2%), PSN (13.4%), and PHN (3.3%). Across subtypes, the most widely reported symptoms were numbness (range: 62.2%–89.7%) and hyperalgesia (range: 32.1%–76.9%) and the most commonly prescribed pain analgesics were NSAID (range: 18.2%–57.1%), opioids (range: 0.0%–39.3%), and antiepileptics (range: 18.2%–57.1%). PTN and PSN patients reported the least favorable EQ-5D index scores (M=0.42, SD=0.19) and BPI-Pain Severity scores (M=7.0, SD=1.9), respectively. Those diagnosed with CNP had the least favorable BPI-Pain Interference scores (M=6.0, SD=2.7). Patients with PHN reported the least impairment based on EQ-5D index scores (M=0.60, SD=0.04). Those with pDPN had the most favorable BPI scores (BPI-Pain Severity: M=4.6, SD=2.3; BPI-Pain Interference: M=4.7, SD=2.7). CONCLUSION: Evaluation of chronic pain patients in Brazil yielded a 14.5% probable NeP prevalence. NSAIDs and opioids were commonly used, and there was a high incidence of NeP-related symptoms with varying levels of dysfunction across subtypes.