Abstract
INTRODUCTION: Peripheral neuropathic pain after nerve injury (PNI) caused by surgery or trauma can severely impact daily life. The high-concentration capsaicin patch (HCCP, 179 mg) is a topical therapy approved for peripheral neuropathic pain, including PNI. This study utilizes data from the German Pain e-Registry (GPeR) to investigate the real-world effectiveness of HCCP in managing PNI across multiple treatments over 1 year. METHODS: CASPAR is a retrospective, non-interventional cohort study investigating patients with peripheral neuropathic pain treated with HCCP. The present analysis included 499 patients with PNI who received ≥ 1 HCCP with ≥ 12 months of follow-up. Key measures included pain intensity, quality of life (QoL), affective distress, sleep disturbances, and overall functioning. Furthermore, analgesic use and adverse events associated with HCCP treatment were evaluated. RESULTS: The mean average daily pain intensity (API) decreased from 52.5 mm on the visual analog scale (VAS) at baseline to 21.5 mm at month 12 in patients receiving four HCCPs. At month 12, a ≥ 30% reduction in API was observed in 25.8%, 44.9%, 85.3%, and 97.8% of patients receiving one, two, three, and four HCCP treatments, respectively. Significant improvements were also noted in physical and mental QoL, sleep, mood, and daily functioning. Patients receiving three or four HCCP treatments maintained pain relief and symptom improvements over the 12-month period, whereas those who discontinued treatment after one or two treatments experienced symptom rebound. In addition, repeated HCCP treatments were associated with a marked reduction in concomitant analgesic use and an increase in days of normal activities. Adverse events were mild-to-moderate application-site reactions, consistent with the well-established safety profile of HCCP. CONCLUSIONS: HCCP treatment is associated with reductions in pain intensity and improvements in sleep, mood, and overall QoL in patients with PNI. These benefits are amplified with continued treatment and are accompanied by reduced use of concomitant analgesics and more days of usual activities, although a direct causal relationship cannot be confirmed within the context of this observational study. CLINICAL TRIAL REGISTRATION: EU PAS number: EUPAS1000000106.