Eliciting health state utilities from the general public for severe chronic pain.

OBJECTIVE: There is an absence of data on public preferences for health states (HSs) associated with severe chronic pain. The aim of this study was to develop accurate HS descriptions for severe chronic pain requiring intrathecal (IT) therapy and to derive utility weights that describe the health-related quality of life (HRQL) impact of chronic pain associated with malignant (MP) and non-malignant (NMP) aetiologies. RESEARCH DESIGN AND METHOD: Eight visual analogue scale pain index (VAS-PI) HSs were defined using ranges 0-40, 41-60, 61-80 and 81-100 applied to both MP and NMP. Additionally, eight HSs representing common adverse events associated with IT therapy were identified. The content and description of the HSs were ascertained by interviews with five United Kingdom clinical experts. In total, 16 HSs were compiled. These HS descriptions and HS questionnaires were administered to 102 members of the public, utilising a time trade off (TTO) approach to estimate utilities for the HSs. RESULTS: Participants generally were well matched to the general public in England and Wales, with some differences in mean age, race and education. A substantial decline in utility was observed with more severe VAS-PI values. The mean TTO utility values also decreased from mild pain to severe pain. Participants were able to differentiate between the side effects. CONCLUSION: The study shows a clear decrement in utility moving from different severity levels of severe chronic pain.

Cost-effectiveness of ziconotide in intrathecal pain management for severe chronic pain patients in the UK.

OBJECTIVE: To examine the cost-effectiveness of using intrathecal ziconotide in the treatment of severe chronic pain compared to best supportive care for patients with intractable chronic pain in the United Kingdom. METHODS: Using a simulation model, the analysis evaluated the cost and health economic consequences of using ziconotide as a treatment for severe chronic pain. The modelled population and clinical data were based on a randomised controlled trial in which the main outcome was reduction in pain as measured by the visual analogue scale of pain intensity (VASPI). Resource use data were elicited using a modified Delphi panel and costed using published sources. Utility values were derived from a separate research study. The main outcome measure was the cost per quality-adjusted life-year (QALY). Extensive scenario analysis was conducted to evaluate parameter uncertainty. RESULTS: Overall, findings were robust to most assumptions. The cost-effectiveness of ziconotide compared to best supportive care (BSC) was pound 27,443 per QALY (95% CI pound 18,304-38,504). Scenarios were investigated in which discount rates, the time horizon, the threshold for qualifying as a responder, pump-related assumptions, utilities, ziconotide drug dose, and the patient discontinuation rate with ziconotide were varied. The most sensitive parameter was the dosage of ziconotide: using the lower and upper bounds of the average ziconotide dosage observed in the long-term open-label study changed the incremental cost-effectiveness ratio (ICER) to pound 15,500 [pound 8206-25,405] and pound 44,700 [pound 30,541-62, 670]. CONCLUSIONS: Ziconotide may offer an economically feasible alternative solution for patients for whom current treatment is inappropriate or ineffective. The main study limitation is that some model inputs, mainly related to resource use, are based on assumptions or expert interviews.