MADRID – The CASPAR study, presented at the 60th Annual Congress of the European Association for the Study of Diabetes (EASD)[1]confirms the interest of high concentration capsaicin patches with, over 12 months and up to 4 prescribed treatments, a reduction in pain intensity scores, an improvement in burning sensations, tingling and numbness, but also a reduction in concomitant analgesics.
Up to 50% of people with diabetes suffer from diabetic peripheral neuropathy [2] [3]nearly half of whom will develop neuropathic pain [4]. In the presence of localized pain, capsaicin patches are recommended as a second line of therapy (at a rate of 1 to 4 patches every 3 months) like botulinum toxin A, after lidocaine plasters and before strong opioids or neurostimulation, according to the latest recommendations of the French Society for the Study and Treatment of Pain (SFETD)[5].
A real-life evaluation of capsaicin patches
Detailed at EASD 2024, CASPAR is a 12-month retrospective cohort study conducted from the German Pain Registry (iDocLive) managed by the German Pain Association and fed by more than 2,000 physicians (data provided by patients and validated by clinical examinations). The results, despite the limitations specific to this type of analysis, show the relief provided by high-concentration capsaicin patches (179 mg) in patients suffering from painful diabetic peripheral neuropathy.
In CASPAR, 826 patients were included who had been diagnosed with painful diabetic peripheral neuropathy (mean age: 66.8 years; mean pain duration: 5 years) and had been treated at least once with the high-concentration capsaicin patch. They were followed up for 12 months. Assessment of neuropathic pain symptoms using the Pain Detect Questionnaire (PDQ-7) score was performed at baseline and after each treatment. The use of concomitant analgesic medications was also assessed before and after initiation of capsaicin treatment.
Of the 826 patients, all received at least one capsaicin patch treatment. 79% received two, 56% received three, and 34% received four treatments over the 1-year period (recommended treatment intervals are at least 90 days). The mean 24-hour pain score (average 24-hr pain intensity/API, scale 0 to 100) at baseline was 57.5 ± 18.2 and decreased to 16 in patients who received four capsaicin treatments (279 patients) (p < 0.001).
The PDQ-7 (7-item pain DETECT questionnaire/PDQ-7; score range 0–35) total score at baseline averaged 22.1 and decreased to 18.2, 17.8, 17.8, and 17.8 after 1, 2, 3, and 4 treatments, respectively. The most prominent initial symptoms were burning, tingling, pins and needles, and numbness.
Graph: Individual symptom scores at baseline and after 4 treatments
Legend : Burning: burning sensation; Tingling: tingling; Allodynia: allodynia; Pain attack: painful crisis; Thermal hyperalgesia: thermal hyperalgesia; Numbness: numbness; Pressure-evoked pain: pain caused by pressure. Source EASD.
If the patient received only one treatment, the pain decreased, but it tended to increase again. On the other hand, if the patient continued the treatment, the intensity of the pain gradually decreased.
A reduction in concomitant analgesics
Before receiving the capsaicin patches, 100% of patients were taking pain medications, an average of 7.7 +/- 2.5 medications. After starting treatment with the capsaicin patch, they were still taking an average of 4 +/- 1.6 concomitant pain medications in addition to the patch. After four treatments with capsaicin patches, 27.8% of patients were completely free of concomitant analgesics. A decrease in the use of antidepressants, antiepileptics, and even strong opioids was also observed.
Regarding the tolerance of the treatment, topical application of the high concentration capsaicin patch may cause local reactions such as pain and redness, usually observed after the first treatment. However, as patients become accustomed to the treatment, the frequency of these local reactions decreases.
High Concentration Capsaicin Patches, an Option to Consider
It has already been shown that high-concentration capsaicin application in focal neuropathic pain provides a lasting effect for about three months. The CASPAR study here demonstrates substantial pain relief, improvement in pain symptoms, and a reduction in the use of concomitant analgesic medications. This result was expected, as capsaicin acts on small nerve fibers, including sensitized C fibers, resting them for about three months, thereby reducing the pain sensation.
But beyond the relief obtained, capsaicin could have a disease-modifying effect, similar to what is observed in post-chemotherapy neuropathy, where the painful area gradually reduces with its use.
An ongoing analysis of the CASPAR study seeks to identify pain phenotypes that are particularly responsive to capsaicin treatment.
Experts’ interests: Study co-designed with the German Pain Association, funded by Grunenthal GmbH.
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