Effectiveness of the capsaicin 8% patch in the management of peripheral neuropathic pain in European clinical practice: the ASCEND study

Abstract

Background: In randomised studies, the capsaicin 8% patch has demonstrated effective pain relief in patients with peripheral neuropathic pain (PNP) arising from different aetiologies.

Methods: ASCEND was an open-label, non-interventional study of patients with non-diabetes-related PNP who received capsaicin 8% patch treatment, according to usual clinical practice, and were followed for ≤52 weeks. Co-primary endpoints were percentage change in the mean numeric pain rating scale (NPRS) 'average daily pain' score from baseline to the average of Weeks 2 and 8 following first treatment; and median time from first to second treatment. The primary analysis was intended to assess analgesic equivalence between post-herpetic neuralgia (PHN) and other PNP aetiologies. Health-related quality of life (HRQoL, using EQ-5D), Patient Global Impression of Change (PGIC) and tolerability were also assessed.

Results: Following first application, patients experienced a 26.6% (95% CI: 23.6, 29.62; n = 412) reduction in mean NPRS score from baseline to Weeks 2 and 8. Equivalence was demonstrated between PHN and the neuropathic back pain, post-operative and post-traumatic neuropathic pain and 'other' PNP aetiology subgroups. The median time from first to second treatment was 191 days (95% CI: 147, 235; n = 181). Forty-four percent of all patients were responders (≥30% reduction in NPRS score from baseline to Weeks 2 and 8) following first treatment, and 86.9% (n = 159/183) remained so at Week 12. A sustained pain response was observed until Week 52, with a 37.0% (95% CI: 31.3, 42.7; n = 176) reduction in mean NPRS score from baseline. Patients with the shortest duration of pain (0-0.72 years) experienced the highest pain response from baseline to Weeks 2 and 8. Mean EQ-5D index score improved by 0.199 utils (responders: 0.292 utils) from baseline to Week 2 and was maintained until Week 52. Most patients reported improvements in PGIC at Week 2 and at all follow-up assessments regardless of number of treatments received. Adverse events were primarily mild or moderate reversible application site reactions.

Conclusion: In European clinical practice, the capsaicin 8% patch provided effective and sustained pain relief, substantially improved HRQoL, improved overall health status and was generally well tolerated in a heterogeneous PNP population.

Trial registration: NCT01737294 Date of registration - October 22, 2012.

Keywords: Capsaicin 8% patch; Health-related quality of life; Neuropathy; Numeric pain rating scale; Pain management; Peripheral neuropathic pain; Topical analgesic.

Fig. 1

Schedule of patient assessments. *Numeric pain rating scale (NPRS) ‘average pain during the last seven days’ score was recorded at the screening visit and used as the baseline pain score. NPRS ‘average pain during the last 24 h’ score was recorded at treatment visits and assessments; ^‡Week 2 and Week 8 assessments were performed only after first capsaicin 8% patch treatment. EQ-5D, EuroQol 5 Dimension 3-level; PGIC, patient global impression of change

Fig. 2

Percentage change in mean NPRS ‘average daily pain’ score following first treatment (a) from baseline to Weeks 2 and 8 and (b) from baseline to each assessment. The margin of equivalence for percentage change in mean NPRS score was set at ±16% (comparable to a one-point change on the NPRS scale). Error bars represent 95% confidence intervals. CRNP, cancer-related neuropathic pain; HIV-AN, HIV associated neuropathy; NBP, neuropathic back pain; NPRS, numeric pain rating scale; Other, other non-diabetic PNP; PHN, postherpetic neuralgia; PONP, post-operative and post-traumatic neuropathic pain; W, week

Fig. 3

Capsaicin 8% patch re-treatment intervals between (a) first and second treatment and second and third treatment; and (b) time between first and second treatment by aetiology group. NBP, neuropathic back pain; Other, other non-diabetic PNP; PHN, postherpetic neuralgia; PONP, post-operative and post-traumatic neuropathic pain