Polycythaemia vera (PV) is an example of a slowly progressing disease where trial outcomes mainly consist of effects on surrogate endpoints.
Jonas Hjelmgren and Kristoffer Nilsson at IHE developed an economic model to assess the economic consequences of novel therapies in PV. The model uses JAK2 burden as a surrogate marker to predict disease progression and overall survival in PV.
This is the first published model in PV and one of the few economic models available in myeloproliferative neoplasms which is a group of rare “blood cancer” diseases.
The article presents an external validation of the economic model developed by Hjelmgren and Nilsson in collaboration with Professor Gunnar Birgegård at Uppsala University. The model was validated using published real-world cohort studies of patients with PV.
The key points of this validations were:
- The model’s predictions of cumulative DP were somewhat lower than the published studies.
- Over 20 years’ time, our base case model predicted a mean OS for a PV patient (15.0–16.5 years), which was in line with the published studies (15.8–17.5 years).
- Modeled mean OS was almost two years longer (1.6–1.9 years) for patients with JAK2 <50% than patients with JAK2 ≥50%, which implies the value of keeping JAK2 burden as low as possible using relevant treatment options.
Although the model was found to generate OS estimations that were in line with results of published data the study identified areas of future research in economic modelling of PV. One question discussed was to what extent improved model predictions could be derived from real-world data sources capturing longitudinal evolution of JAK2. Such data are currently scarce and future observational studies should be designed to capture the long-term impact of JAK2 on disease progression and mortality in PV. Apart from the methodologic discussion of using JAK2 as a surrogate endpoint in modelling the authors also discussed the importance of upgrading the status of JAK2 as an outcomes in the assessment of PV response rates, especially as there are now novel treatment options available targeting JAK2.
Journal of Health Economic and Outcomes Research, 2020;7(1):61-70