The NHS is a key battleground in this general election, and beats Brexit as the top public concern. The main political parties are competing over how much investment in the NHS they plan. On major reform there is little beyond support of the NHS’s own Long Term Plan, although Labour has already made “the NHS is not for sale” and “no to privatising the NHS” central to its election messaging.

While privatisation is an important issue for some voters, evidence on it is surprisingly weak. Even quantifying the amount of NHS funds spent by Clinical Commissioning Groups, NHS Trusts, and NHS England on private providers of care is hard to pin down. For example, do general practices count as private providers? Evidence of the impact of competitive tendering for care by CCGs is similarly opaque, as is the basis for a reduction in the requirement to tender, recently proposed by NHS England.

The Conservatives are unlikely to fight back on the privatisation debate. Despite live public concerns over the possible impact of trade deals with the US and other countries, policies to encourage competition and working with private providers in the NHS have waned. The high watermark arguably came in the 2000’s, and the 2012 Health and Care Act was last attempt. Since then, policy, via the NHS Five Year Forward View (2014) and NHS Long Term Plan (2019), shifted from competition to collaboration between providers. NHS England and NHS Improvement’s legislative proposals not only abolish the requirement for NHS bodies to tender competitively for services above a certain value, but also remove the power of the Competition and Markets Authority (CMA) to adjudicate over mergers involving NHS foundation Trusts. This direction is supported by all of the main parties in an unusual consensus. Is this the end of history? If so is it right? What’s the evidence?

Thirty years’ of policies to promote competition in the NHS to improve care for patients starting in 1991 has been dogged by serious gaps in the evidence base, but no shortage of heated anecdote. Even the best available academic and quantitative evidence on impact appears mixed, weak, or frankly implausible. A recent study published by the CMA, which hit the headlines earlier this year claiming “competition ultimately benefits patients” and that a hypothetical future merger between two neighbouring hospitals could—assuming no offsetting clinical benefits are unlocked by the merger—result in an increase in 41% of incidents of harm to patients and an increase in inpatient mortality, illustrates why developing a robust evidence base has been so difficult. This is explored in a longer paper.

First, policymakers often favour quantitative over qualitative evidence to inform (or confirm) their preferred course of action. But quantitative researchers (usually economists) using aggregate datasets to measure the impact of competition and privatisation are often distant from reality in the NHS and rely on narrow theoretical frameworks to construct studies. These cannot easily be challenged by people who know how the NHS really works. The risk is two-fold: that the design of research is not sophisticated enough to answer the key question; and that the results of research show associations between competition and quality of care that are not causative, with the wrong conclusions drawn.

Second, the measure of competition generally used in such quantitative studies is not a measure of competition at all, but of concentration—that is, how many hospitals are geographically near each other and therefore potentially vying for the local patient population. If a positive association between “competition” and quality of care is found, another interpretation is that more isolated hospitals do worse. Past examples include Mid Staffordshire, Barrow-in-Furness, and the Isle of Wight. The conclusions of the CMA working paper might equally be: “a lack of collaboration between professional staff across Trusts is associated with lower-quality care”; or “more isolated hospitals were not able to respond to a range of quality-enhancing policies.”

How might quantitative researchers do better in the future? They might start by understanding the real context that the NHS is working in not just in theory, and use this to design the study at the outset, ideally using mixed methods. They could bother to work up some plausible theories of change to understand causation. Competition should be defined clearly: competition is not concentration. And researchers should be transparent about the assumptions underlying the analysis and weaknesses of the study, and rigorous about conclusions, avoiding overclaiming about causation that looks fishy.

What is striking about the body of research on competition is not its quality but the glaring gaps. Reasons why include that researchers often plough narrow furrows in single disciplines because of academic incentives, the major funding sources for research may not encourage creative and wider investigation, policymakers may not be asking the right questions, or are just not concerned enough with the evidence. For example, we still lack an unbiased description of trends and patterns in choice and competition, a meaningful measure of competition, and how the national tariff incentivises or not competition among NHS Trusts. And this after three decades. 

Why does it matter? New governments can bring major reforms. Flying so blind as to their impact is a big risk to future policymaking that is avoidable and deserves far more attention. If there is another big lurch in policy post a Brexit, those of us funding and generating evidence should do better. Otherwise we might just hand more of the job over to the politicians…

Jennifer Dixon is the chief executive of the Health Foundation.

Competing interests: None declared