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Chris Sampson’s journal round-up for 12th August 2019

Every Monday our authors provide a round-up of some of the most recently published peer reviewed articles from the field. We don’t cover everything, or even what’s most important – just a few papers that have interested the author. Visit our Resources page for links to more journals or follow the HealthEconBot. If you’d like to write one of our weekly journal round-ups, get in touch.

Developing open-source models for the US health system: practical experiences and challenges to date with the Open-Source Value Project. PharmacoEconomics [PubMed] Published 7th August 2019

PharmacoEconomics will soon publish a themed issue on transparency in decision modelling (to which I’ve contributed), and this paper – I assume – is one that will feature. At least one output from the Open-Source Value Project has featured in these round-ups before. The purpose of this paper is to describe the experiences of the initiative in developing and releasing two open-source models, one in rheumatoid arthritis and one in lung cancer.

The authors outline the background to the project and its goal to develop credible models that are more tuned-in to stakeholders’ needs. By sharing the R and C++ source code, developing interactive web applications, and providing extensive documentation, the models are intended to be wholly transparent and flexible. The model development process also involves feedback from experts and the public, followed by revision and re-release. It’s a huge undertaking. The paper sets out the key challenges associated with this process, such as enabling stakeholders with different backgrounds to understand technical models and each other. The authors explain how they have addressed such difficulties along the way. The resource implications of this process are also challenging, because the time and expertise required are much greater than for run-of-the-mill decision models. The advantages of the tools used by the project, such as R and GitHub, are explained, and the paper provides some ammunition for the open-source movement. One of the best parts of the paper is the authors’ challenge to those who question open-source modelling on the basis of intellectual property concerns. For example, they state that, “Claiming intellectually property on the implementation of a relatively common modeling approach in Excel or other programming software, such as a partitioned survival model in oncology, seems a bit pointless.” Agreed.

The response to date from the community has been broadly positive, though there has been a lack of engagement from US decision-makers. Despite this, the initiative has managed to secure adequate funding. This paper is a valuable read for anyone involved in open-source modelling or in establishing a collaborative platform for the creation and dissemination of research tools.

Incorporating affordability concerns within cost-effectiveness analysis for health technology assessment. Value in Health Published 30th July 2019

The issue of affordability is proving to be a hard nut to crack for health economists. That’s probably because we’ve spent a very long time conducting incremental cost-effectiveness analyses that pay little or no attention to the budget constraint. This paper sets out to define a framework that finally brings affordability into the fold.

The author sets up an example with a decision-maker that seeks to maximise population health with a fixed budget – read, HTA agency – and the motivating example is new medicines for hepatitis C. The core of the proposal is an alternative decision rule. Rather than simply comparing the incremental cost-effectiveness ratio (ICER) to a fixed threshold, it incorporates a threshold that is a function of the budget impact. At it’s most basic, a bigger budget impact (all else equal) means a greater opportunity cost and thus a lower threshold. The author suggests doing away with the ICER (which is almost impossible to work with) and instead using net health benefits. In this framework, whether or not net health benefit is greater than zero depends on the size of the budget impact at any given ICER. If we accept the core principle that budget impact should be incorporated into the decision rule, it raises two other issues – time and uncertainty – which are also addressed in the paper. The framework moves us beyond the current focus on net present value, which ignores the distribution of costs over time beyond simply discounting future expenditure. Instead, the opportunity cost ‘threshold’ depends on the budget impact in each time period. The description of the framework also addresses uncertainty in budget impact, which requires the estimation of opportunity costs in each iteration of a probabilistic analysis.

The paper is thorough in setting out the calculations needed to implement this framework. If you’re conducting an economic evaluation of a technology that could have a non-marginal (big) budget impact, you should tag this on to your analysis plan. Once researchers start producing these estimates, we’ll be able to understand how important these differences could be for resource allocation decision-making and determine whether the likes of NICE ought to incorporate it into their methods guide.

Did UberX reduce ambulance volume? Health Economics [PubMed] [RePEc] Published 24th June 2019

In London, you can probably – at most times of day – get an Uber quicker than you can get an ambulance. That isn’t necessarily a bad thing, as ambulances aren’t there to provide convenience. But it does raise an interesting question. Could the availability of super-fast, low-cost, low-effort taxi hailing reduce pressure on ambulance services? If so, we might anticipate the effect to be greatest where people have to actually pay for ambulances.

This study combines data on Uber market entry in the US, by state and city, with ambulance rates. Between Q1 2012 and Q4 2015, the proportion of the US population with access to Uber rose from 0% to almost 25%. The authors are also able to distinguish ‘lights and sirens’ ambulance rides from ‘no lights and sirens’ rides. A difference-in-differences model estimates the ambulance rate for a given city by quarter-year. The analysis suggests that there was a significant decline in ambulance rates in the years following Uber’s entry to the market, implying an average of 1.2 fewer ambulance trips per 1,000 population per quarter.

There are some questionable results in here, including the fact that a larger effect was found for the ‘lights and sirens’ ambulance rate, so it’s not entirely clear what’s going on. The authors describe a variety of robustness checks for our consideration. Unfortunately, the discussion of the results is lacking in detail and insight, so readers need to figure it out themselves. I’d be very interested to see a similar analysis in the UK. I suspect that I would be inclined to opt for an Uber over an ambulance in many cases. And I wouldn’t have the usual concern about Uber exploiting its drivers, as I dare say ambulance drivers aren’t treated much better.



  • Chris Sampson

    Founder of the Academic Health Economists' Blog. Principal Economist at the Office of Health Economics. ORCID: 0000-0001-9470-2369


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