A standard gamble study to determine health state utilities associated with seizures in glioma in the UK.

BACKGROUND: Glioma are infiltrative primary brain tumours, which despite treatment, lead to a substantial reduction in life expectancy. Seizures are a common symptom of glioma, and have a serious impact on patient health related quality of life (HRQoL). OBJECTIVE: The study aimed to estimate health state utility values for different types of seizures related to glioma, a serious type of brain tumour. METHODS: Vignettes for the different health states were initially developed from the existing literature. The health states were then refined in collaboration with patients with previous experience of seizures and clinicians experienced in treating patients with seizures. The final vignettes represented three types of acute seizure: focal aware, focal impaired awareness and tonic clonic and several different health states which combined these acute seizures with other aspects of HRQoL. These vignettes were evaluated by a sample of the UK general public using an online survey and analysed descriptively using the mean and standard deviation. RESULTS: 302 participants, representative of the UK general population in terms of age, sex and geographical region, were included in the estimation sample. For the health states representing acute seizures, the focal aware seizure had the highest mean utility value (0.607), followed by the impaired awareness seizure (0.593) and the tonic clonic seizure (0.522). For the health states that also incorporated wider aspects of HRQoL, the health state utility values ranged from 0.504 (one focal aware seizure per year) to 0.337 (at least one focal impaired awareness seizure per week). CONCLUSIONS: Seizures may have a major impact of the HRQoL of patients with glioma. The utility values obtained in the study may be used in future economic evaluations of interventions related to glioma where seizures are either a primary clinical outcome or an adverse event.