Abstract
Introduction. A five-item Self-Assessment of Treatment (SAT) was developed to assess improvement and satisfaction with treatment associated with the application of a novel high concentration 8% capsaicin topical patch in clinical trials in patients with postherpetic neuralgia (PHN). This study evaluated the item performance and psychometric properties of the SAT. Methods. The SAT, Brief Pain Inventory, SF-36v2, Short-Form McGill Pain Questionnaire, and Patient and Clinician Global Impression of Change (PGIC; CGIC) scores were measured in two 12-week Phase 3 clinical trials. Factor analysis assessed the underlying factor structure, followed by examination of the reliability and validity of the multi-item domain. Results. Pooled data from 698 patients completing SAT after 12 weeks of treatment were analyzed. A one-factor model combining three of the five items emerged as the optimal solution. Internal consistency reliability of this treatment efficacy factor was high (Cronbach's alpha = 0.89). Construct validity was demonstrated by moderate to high correlations with change in other study endpoints. SAT mean scores consistently discriminated between patient change groups defined by PGIC and CGIC. Conclusions. The measurement properties of the three-item version of SAT are valid and reliable for assessment of treatment with a high concentration capsaicin patch among patients with PHN.
Highlights
A five-item Self-Assessment of Treatment (SAT) was developed to assess improvement and satisfaction with treatment associated with the application of a novel high concentration 8% capsaicin topical patch in clinical trials in patients with postherpetic neuralgia (PHN)
The European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) approved the use of a high concentration capsaicin topical patch 8% (QUTENZA) for the treatment of peripheral neuropathic pain in nondiabetic adults, either alone or in combination with other medicinal products for pain (EU label), and the management of neuropathic pain associated with postherpetic neuralgia (US label), based on the results from two Phase 3 randomized, double-blind, dose-controlled trials in subjects with PHN [3, 4]
Patient-Reported Outcome (PRO) scores prior to the start of treatment provide an overall description of patient condition (Table 4)
Summary
A five-item Self-Assessment of Treatment (SAT) was developed to assess improvement and satisfaction with treatment associated with the application of a novel high concentration 8% capsaicin topical patch in clinical trials in patients with postherpetic neuralgia (PHN). The measurement properties of the threeitem version of SAT are valid and reliable for assessment of treatment with a high concentration capsaicin patch among patients with PHN. The European Medicines Agency (EMA) and the US Food and Drug Administration (FDA) approved the use of a high concentration capsaicin topical patch 8% (QUTENZA) for the treatment of peripheral neuropathic pain in nondiabetic adults, either alone or in combination with other medicinal products for pain (EU label), and the management of neuropathic pain associated with postherpetic neuralgia (US label), based on the results from two Phase 3 randomized, double-blind, dose-controlled trials in subjects with PHN [3, 4]. The agonist effect of capsaicin at VR1 receptors results in the defunctionalization of sensory nerve endings [4]
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