Presentation (CTI)

OBJECTIVES: Choroidal melanoma (CM) is a rare malignant tumour, with treatments evolving from primary enucleation toward eye-preserving approaches. Current cost-effectiveness models (CEMs) tend to focus on oncological aspects overlooking visual morbidity. The aim was to develop a CEM structure, that incorporates both aspects of the disease through structured model conceptualisation.
METHODS: The structured model conceptualisation process undertaken included: 1) review of clinical guidelines, previous health technology assessments, and published economic models evaluating whether existing approaches adequately reflect the dual burden of disease, 2) development of influence diagram, 3) model conceptualisation, 4) elicitation of clinical/patient experience and validation of model assumptions and 5) model finalisation.
RESULTS: Review of prior HTA submissions and published economic models confirmed that no existing model has structurally incorporated both visual morbidity and oncological outcomes. A novel cohort state-transition model was developed tracking and linking cancer and visual acuity outcomes over time. Clinical/patient experience highlighted the importance of treatment related complication and the effect of visual impairment besides visual acuity, and the model concept was revised.
The final model’s oncological dimension tracks patients from primary tumour control through to progression and death, with impacts of adverse events and metastasis captured within this structure. The visual dimension tracks patients across visual impairment (VI) categories (including visual acuity and other complications) , with time-dependent transition probabilities reflecting the natural trajectory of vision loss following treatment. Whilst modelled independently, the two dimensions interact: progression triggers subsequent treatment, shaping the VI trajectory. Enucleation is captured separately, reflecting quality of life impacts beyond VI category alone.
CONCLUSIONS: Structured model conceptualisation with early clinical and patient expert involvement is essential to capture all dimensions of complex diseases. In CM, this resulted in a novel model structure incorporating both tumour progression and visual morbidity, allowing the evaluation of the full impact of treatments.