OBJECTIVES: This study was designed to capture utility values for health states related to malignant (MP) and non-malignant (NMP) severe chronic pain treated with intrathecal (IT) analgesia. METHODS: Literature review and in depth interviews with clinical experts (n=5) led to the development of health state descriptions. These were defined using visual analogue scale of pain intensity (VASPI) ranges 0-40, 41-60, 61-80 and 81-100 for both MP and NMP. Additionally 8 health states representing common adverse events associated with IT therapy were produced. A discussion guide based on the dimensions of the EQ-5D was developed. Health states were piloted with cognitive debriefing with five members of the UK general public. Time trade off interviews were administered to the UK general public (n=102) to estimate utilities for the health states. A repeated measurement model on the TTO utilities was estimated to account for intra-patient correlation in the data. Using the predicted values from this model, utilities were obtained for all possible VASPI scores. RESULTS: Participants were generally well matched to the census profile of England and Wales with some small differences in mean age, race and education. Utilities ranged from 0.84 for VASPI 0-40 (for NMP & MP) to -0.15 and -0.20 for VASPI 81-100 (NMP & MP respectively). The values for side effects (irrespective of the context of chronic pain) were as follows dizziness (0.40); nausea (0.45); pruritis (0.82); confusional state (0.41); abnormal gait (0.67); urinary retention (0.69); weight gain (0.77) and erectile dysfunction (0.69). The results also show a substantial decline in utility scores related to more severe VASPI values for non-malignant, and malignant disease. CONCLUSION: The study shows a significant decrement in utility moving from less severe to more severe levels of chronic pain. The general public recognise the very significant impact that severe chronic pain has on HRQL.