New publication in Medical Decision Making: quality-adjusted life years from joint models
At a glance
A framework for estimating quality-adjusted life years from one joint model of quality of life and survival, published open access, with jmqaly as its software in Stata.
Our paper A Framework for the Estimation of Quality-Adjusted Life-Years Using Joint Models of Longitudinal and Survival Data is published, open access, in Medical Decision Making (2026; 46(7): 874–886). Its authors are Michael Crowther, PhD; Alessandro Gasparini, PhD, then at Red Door Analytics; Sara Ekberg, PhD; Federico Felizzi; Elaine Gallagher; and Noman Paracha.
Quality-adjusted life years, or QALYs, combine length and quality of life in one measure, and are widely used in health technology assessment to express the benefit of a treatment. They are usually calculated from a few discrete health states, each given a quality-of-life value, with quality of life and survival modelled separately.
The paper estimates QALYs in continuous time from one joint model of each patient's repeated health-utility measurements and their overall survival, fitted by maximum likelihood to patient-level data. Because both come from the same model, the QALY keeps the association between quality of life and survival that the joint model estimates.
In simulation studies under realistic data-generating mechanisms, the joint model recovered the true QALYs without bias. A comparison method that calculated QALYs from the health-utility trajectories alone, ignoring the survival process, was biased in most scenarios.
The software. The paper's estimators are implemented in jmqaly, our Stata command for QALYs after a joint model fitted with merlin. It gives the QALY to a horizon you choose, or over a lifetime, for one covariate pattern or as the difference between two, with optional discounting. jmqaly 1.6.5 installs from this website and needs StataNow 19.5 and merlin 2.5.0. An R version will follow.
We thank our collaborators Alessandro Gasparini, PhD; Federico Felizzi; Elaine Gallagher; and Noman Paracha for their work on this paper.
At ISPOR Europe 2026. QALYs are at the centre of the health economics and outcomes research that ISPOR Europe brings to Vienna from Sunday 8 to Wednesday 11 November. Michael Crowther, PhD, and Rickard Strandberg, PhD, are there with three posters and would be glad to talk about estimating QALYs from patient-level data. Come and find them, or get in touch to arrange a time.