[3] She also co-leads, alongside Rebecca Shipley, UCL's CHIMERA research hub which analyses data from critically ill hospital patients.

[6] In 2005 she left physics, returning to London to take up a position with the UCL Clinical Operational Research Unit applying mathematics to problems in health care.

In 2016, Pagel was awarded a Harkness Fellowship in Health Care Policy and Practice by the Commonwealth Fund,[7] through which Pagel spent 2016–2017 in the USA researching (a) the priorities of Republican and Democrat politicians for the goals of national health policy working with the Milbank Memorial Fund and (b) how clinical decision support systems can be better implemented within intensive care settings.

[5] She focuses on mortality and morbidity outcomes following cardiac surgery in children and adults in the UK, leading and contributing to several large national projects;[11][12][13][14] understanding the course of a child's stay in paediatric intensive care;[15] mathematical methods to support service delivery within hospitals.

[17] Pagel was instrumental in developing a statistical model to take into account the complexity of individual children with congenital heart disease, when considering a hospital's survival rate.

[31] Pagel uses tools from her research to design and analyse political data from public polls, particularly in the context of Brexit[32][33][34][35] and health policy,[36][37] and she is known as a regular podcast contributor on both themes.

In 2019, Pagel was awarded the Lyn Thomas Impact Medal from the Operational Research Society, along with her colleagues Sonya Crowe and Martin Utley.