From waiting times to waiting lists: Theory and evidence on the role of hospital mergers in the English NHS

This paper studies the impact of hospital mergers on waiting lists for elective treatments, both theoretically and empirically. We develop a model of hospital competition with regulated prices in a spatial framework, building on Brekke et al. (2008), where patients choose providers based on travel distance and waiting lists, and hospitals maximise a combination of profits and patient utility. We show that mergers internalise two key competition externalities: (i) altruistic competition to attract patients and (ii) incentives to avoid unprofitable patients.

Empirically, we use a 19-year panel (2000–2018) of English NHS hospitals and estimate a multi-period Difference-in-Differences model with staggered treatment timing. We find that mergers involving profit-oriented hospitals (Foundation Trusts) increase waiting lists, whereas mergers involving semi-altruistic hospitals reduce them. These findings are consistent with the theoretical predictions.

From a policy perspective, merger effects are highly heterogeneous and critically depend on hospital objectives.