P-045 - An evaluation of effectiveness of high concentration capsaicin topical system in post herpetic neuralgia

Abstract Title: An evaluation of effectiveness of high concentration capsaicin topical system in post herpetic neuralgia


Background: Postherpetic neuralgia (PHN), a chronic peripheral neuropathic pain (PNP) condition often characterized by localized debilitating pain, is the most common complication of herpes zoster. PHN reduces physical and social functioning, psychological well being and the quality of life of the patients.[1,2]

Capsaicin topical system (HCCTS) is indicated in the USA in adults for the treatment of neuropathic pain associated with PHN since 2009. Locally applied treatments such as HCCTS that target the allodynic or hyperalgesic area with very limited systemic effects may be preferred especially in elderly patients.[3] A recent pooled analysis showed that in elderly patients (≥ 75 years) with PNP, HCCTS is efficacious and has a tolerability profile similar to that observed in adults and therefore provides a valuable alternative to systemic oral therapies in elderly patients, limiting the risk of systemic adverse reactions and the risk of drug–drug interactions with concomitant medications.[4]

As information on repeated treatment with HCCTS in PHN is scarce, we conducted a retrospective cohort study evaluating patients who received at least one and up to 4 HCCTS treatment(s) and were followed up for 12 months using anonymized routine medical care data from the German Pain e-Registry.

Purpose/Objectives: The goal of this study was to evaluate the outcomes of repeated treatments with HCCTS in patients with PHN in a clinical practice setting. Outcomes on pain intensity, pain-related disability including sleep, mood and QoL were investigated in cohorts of patients who received 1, 2, 3 or 4 HCCTS treatments.


Methods: The German Pain e-Registry is a national web-based pain treatment registry developed on behalf of the German Pain Association. The registry prospectively collects routine data of pain patients via the online documentation service iDocLive®. Data are entered predominantly by patients to inform their pain physicians about demographic specifics, pain and pain-related issues such as impairments of daily activities, quality of life, response to treatments and other information as defined by the physician.

A cohort of PHN patients treated with HCCTS and followed up for ≥ 12 months was extracted for the purposes of this analysis. Data were analyzed according to treatments received (cohort 1, 2, 3 and 4 received 1, 2, 3 and 4 HCCTS treatments respectively).

The analysis included a description of baseline characteristics and demographic data. Effectiveness was analyzed based on assessments at baseline and after each HCCTS treatment. The assessments included average pain intensity (VAS), affective distress with the Depression, Anxiety and Stress Scale (DASS-21), physical and mental quality of Life with the Veterans RAND-12 (VR-12), disability caused by pain with the modified pain disability index (mPDI) and more particularly sleep (sleep item of the mPDI).

Concomitant analgesic medication use and treatment related adverse events were analyzed.


Results: The PHN population (n=961) had the following demographic characteristics [mean (SD)]: age [66.8 (13.1)] years, BMI [31.5 (7.1)], duration of PHN [3.3 (3.5)] years. The patients had used on average 7.7 medications for PHN prior to receiving their first HCCTS treatment.

Overall 187 (cohort 1), 209 (cohort 2), 207(cohort 3), 358 (cohort 4) patients received 1, 2, 3 and 4 HCCTS treatments respectively.

Baseline characteristics: all patients received concomitant analgesic medications for the treatment of PHN. The average daily pain intensity score (SD) was 61.8 (17.5) and 43.8% of the patients reported an important impact of pain on their sleep. The proportion of patients strongly impacted by depression, anxiety and stress (defined as scores ≥ 11, ≥8 and ≥ 13 on respective DASS-21 subscales) were 39.5%, 41.8% and 53.4%. Mean (SD) scores on the VR-12 mental component summary (MCS) and physical component summary (PCS) were 42.5 (11.8) and 31.3 (9.1), respectively.

Outcomes: The API decreased to 19.6 mm VAS after 12 months in patients in cohort 4. In patients in cohort 1, 2 and 3, the mean (SD) pain intensities were 54.7 (20.5), 36.7 (16.0), 27.5 (15.1) at 12 months respectively. Average pain intensity (API) reduced significantly (p< 0.001) in all cohorts after the first treatment and continued to decrease with subsequent treatments.

Similar effects (i.e. on average improvements with each consecutive treatment and worsening when treatment was discontinued) have been observed regarding sleep disturbance, effects on mood and Qol.

Twelve months after initiation of treatment, the proportion of patients not using concomitant analgesic medication was 2.7%, 16.7%, 27.5% and 32.7% in cohorts 1, 2, 3 and 4, respectively.

The tolerability profile was mostly characterized by application site reactions.

Conclusions/Implications for future research and/or clinical care: The study included a large population of PHN patients. Although the population had a long duration of PHN prior to inclusion and had tried several other pain treatments to control their PHN, baseline pain scores were consistent with moderate to severe pain. In this population with PHN, effectiveness of HCCTS treatment could be demonstrated. The effectiveness increased with repeated HCCTS treatment consistent with progressive response to treatment reported in the literature.[5] Similar trends were observed on impact on sleep, mood and QoL.

Moreover, effective treatment of pain with HCCTS coincided with a significant decrease in concomitant pain medication when treatment was continued 4 times over the 12 months observation period.

The tolerability profile was consistent with that reported in the literature.


References:

1. Johnson RW, Bouhassira D, Kassianos G, Leplège A, Schmader KE, Weinke T. The impact of herpes zoster and post-herpetic neuralgia on quality-of-life. BMC Med. 8, 37 (2010).


2. Curran D, Schmidt-Ott R, Schutter U, Simon J, Anastassopoulou A. Impact of herpes zoster and postherpetic neuralgia on the quality of life of Germans aged 50 or above. BMC Infect. Dis. 18, 496 (2018).


3. Pickering G, Lucchini C. Topical treatment of localized neuropathic pain in the elderly. Drugs Aging. 2020;37(2):83–89.


4. Pickering G, Engelen S, Stupar M, Ganry H, Eerdekens M. Is the Capsaicin 179 mg (8% w/w) Cutaneous Patch an Appropriate Treatment Option for Older Patients with Peripheral Neuropathic Pain? J Pain Res. 2024 Mar 27;17:1327-1344.


5. Rainer Freynhagen, Charles Argoff, Mariëlle Eerdekens, Sylvia Engelen, Serge Perrot, Progressive Response to Repeat Application of Capsaicin 179 mg (8% w/w) Cutaneous Patch in Peripheral Neuropathic Pain: Comprehensive New Analysis and Clinical Implications, Pain Medicine, Volume 22, Issue 10, October 2021, Pages 2324–2336.