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.

Credits

Chris Sampson’s journal round-up for 5th 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.

The barriers and facilitators to model replication within health economics. Value in Health Published 16th July 2019

Replication is a valuable part of the scientific process, especially if there are uncertainties about the validity of research methods. When it comes to cost-effectiveness modelling, there are endless opportunities for researchers to do things badly, even with the best intentions. Attempting to replicate modelling studies can therefore support health care decision-making. But replication studies are rarely conducted, or, at least, rarely reported. The authors of this study sought to understand the factors that can make replication easy or difficult, with a view to informing reporting standards.

The authors attempted to replicate five published cost-effectiveness modelling studies, with the aim of recreating the key results. Each replication attempt was conducted by a different author and we’re even given a rating of the replicator’s experience level. The characteristics of the models were recorded and each replicator detailed – anecdotally – the things that helped or hindered their attempt. Some replications were a resounding failure. In one case, the replicated cost per patient was more than double the original, at more than £1,000 wide of the mark. Replicators reported that having a clear diagram of the model structure was a big help, as was the provision of example calculations and explicit listing of the key assumptions. Various shortcomings made replication difficult, all relating to a lack of clarity or completeness in reporting. The impact of this on the validation attempt was exacerbated if the model either involved lots of scenarios that weren’t clearly described or if the model had a long time horizon.

The quality of each study was assessed using the Philips checklist, and all did pretty well, suggesting that the checklist is not sufficient for ensuring replicability. If you develop and report cost-effectiveness models, this paper could help you better understand how end-users will interpret your reporting and make your work more replicable. This study focusses on Markov models. They’re definitely the most common approach, so perhaps that’s OK. It might be useful to produce prescriptive guidance specific to Markov models, informed by the findings of this study.

US integrated delivery networks perspective on economic burden of patients with treatment-resistant depression: a retrospective matched-cohort study. PharmacoEconomics – Open [PubMed] Published 28th June 2019

Treatment-resistant depression can be associated high health care costs, as multiple lines of treatment are tried, with patients experiencing little or no benefit. New treatments and models of care can go some way to addressing these challenges. In the US, there’s some reason to believe that integrated delivery networks (IDNs) could be associated with lower care costs, because IDNs are based on collaborative care models and constitute a single point of accountability for patient costs. They might be particularly useful in the case of treatment-resistant depression, but evidence is lacking. The authors of this study investigated the difference in health care resource use and costs for patients with and without treatment-resistant depression, in the context of IDNs.

The researchers conducted a retrospective cohort study using claims data for people receiving care from IDNs, with up to two years follow-up from first antidepressant use. 1,582 people with treatment-resistant depression were propensity score matched to two other groups – patients without depression and patients with depression that was not classified as treatment-resistant. Various regression models were used to compare the key outcomes of all-cause and specific categories of resource use and costs. Unfortunately, there is no assessment of whether the selected models are actually any good at estimating differences in costs.

The average costs and resource use levels in the three groups ranked as you would expect: $25,807 per person per year for the treatment-resistant group versus $13,701 in the non-resistant group and $8,500 in the non-depression group. People with treatment-resistant depression used a wider range of antidepressants and for a longer duration. They also had twice as many inpatient visits as people with depression that wasn’t treatment-resistant, which seems to have been the main driver of the adjusted differences in costs.

We don’t know (from this study) whether or not IDNs provide a higher quality of care. And the study isn’t able to compare IDN and non-IDN models of care. But it does show that IDNs probably aren’t a full solution to the high costs of treatment-resistant depression.

Rabin’s paradox for health outcomes. Health Economics [PubMed] [RePEc] Published 19th June 2019

Rabin’s paradox arises from the theoretical demonstration that a risk-averse individual who turns down a 50:50 gamble of gaining £110 or losing £100 would, if expected utility theory is correct, turn down a 50:50 gamble of losing £1,000 or gaining millions. This is because of the assumed concave utility function over wealth that is used to model risk aversion and it is probably not realistic. But we don’t know about the relevance of this paradox in the health domain… until now.

A key contribution of this paper is that it considers both decision-making about one’s own health and decision-making from a societal perspective. Three different scenarios are set-up in each case, relating to gains and losses in life expectancy with different levels of health functioning. 201 students were recruited as part of a larger study on preferences and each completed all six gamble-pairs (three individual, three societal). To test for Rabin’s paradox, the participants were asked whether they would accept each gamble involving a moderate stake and a large stake.

In short, the authors observe Rabin’s proposed failure of expected utility theory. Many participants rejected small gambles but did not reject the larger gambles. The effect was more pronounced for societal preferences. Though there was a large minority for whom expected utility theory was not violated. The upshot of all this is that our models of health preferences that are based on expected utility may be flawed where uncertain outcomes are involved – as they often are in health. This study adds to a growing body of literature supporting the relevance of alternative utility theories, such as prospect theory, to health and health care.

My only problem here is that life expectancy is not health. Life expectancy is everything. It incorporates the monetary domain, which this study did not want to consider, as well as every other domain of life. When you die, your stock of cash is as useful to you as your stock of health. I think it would have been more useful if the study focussed only on health status and outcomes and excluded all considerations of death.

Credits

Meeting round-up: iHEA Congress 2019

Missed iHEA 2019? Or were you there but could not make it to all of the amazing sessions? Stay tuned for my conference highlights!

iHEA started on Saturday 13th with pre-congress sessions on fascinating research as well as more prosaic topics, such as early-career networking sessions with senior health economists. All attendees got a super useful plastic bottle – great idea iHEA team!

The conference proper launched on Sunday evening with the brilliant plenary session by Raj Chetty from Harvard University.

Monday morning started bright and early with the thought-provoking session on validation of CE models. It was chaired and discussed by Stefan Lhachimi and featured presentations by Isaac Corro Ramos, Talitha Feenstra and Salah Ghabri. I’m pleased to see that validation is coming to the forefront of current topics! Clearly, we need to do better in validating our models and documenting code, but we’re on the right track and engaged in making this happen.

Next up, the superb session on the societal perspective for cost-effectiveness analysis. It was an all-star cast with Mark Sculpher, Simon Walker, Susan Griffin, Peter Neumann, Lisa Robinson, and Werner Brouwer. I’ve live-tweeted it here.

The case was expertly made that taking a single sector perspective can be misleading when evaluating policies with cross-sectoral effects, hence the impact inventory by Simon and colleagues is a useful tool to guide the choice of sectors to include. At the same time, we should be mindful of the requirements of the decision-maker for whom CEA is intended. This was a compelling session, which will definitely set the scene for much more research to come.

After a tasty lunch (well done catering team!), I headed to the session on evaluations using non-randomised data. The presenters included Maninie Molatseli, Fernando Antonio Postali, James Love-Koh and Taufik Hidayat, on case studies from South Africa, Brazil and Indonesia. Marc Suhrcke chaired. I really enjoyed hearing about the practicalities of applying econometric methods to estimate treatment effects of system wide policies. And James’s presentation was a great application of distributional cost-effectiveness analysis.

I was on the presenter’s chair next, discussing the challenges in implementing policies in the southwest quadrant of the CE plane. This session was chaired by Anna Vassall and discussed by Gesine Meyer-Rath. Jack Dowie started by convincingly arguing that the decision rule should be the same regardless of where in the CE plane the policy falls. David Bath and Sergio Torres-Rueda presented fascinating case studies of south west policies. And I argued that the barrier was essentially a problem of communication (presentation available here). An energetic discussion followed and showed that, even in our field, the matter is far from settled.

The day finished with the memorial session for the wonderful Alan Maynard and Uwe Reinhardt, both of whom did so much for health economics. It was a beautiful session, where people got together to share incredible stories from these health economics heroes. And if you’d like to know more, both Alan and Uwe have published books here and here.

Tuesday started with the session on precision medicine, chaired by Dean Regier, and featuring Rosalie Viney, Chris McCabe and Stuart Peacock. Rather than slides, the screen was filled with a video of a cosy fireplace, inviting the audience to take part in the discussion.

Under debate was whether precision medicine is a completely different type of technology, with added benefits over and above improvement to health, and needing a different CE framework. The panellists were absolutely outstanding in debating the issues! Although I understand the benefits beyond health that these technologies can offer, I side with the view that, like with other technologies, value is about whether the added benefits are worth the losses given the opportunity cost.

My final session of the day was by the great Mike Drummond, comparing how HTA has influenced the uptake of new anticancer drugs in Spain versus England (summary in thread below). Mike and colleagues found that positive recommendations do increase utilisation, but the magnitude of change differs by country and region. The work is ongoing in checking that utilisation has been picked up accurately in the routine data sources.

The conference dinner was at the Markthalle, with plenty of drinks and loads of international food to choose from. I had to have an early night given that I was presenting at 8:30 the next morning. Others, though, enjoyed the party until the early hours!

Indeed, Wednesday started with my session on cost-effectiveness analysis of diagnostic tests. Alison Smith presented on her remarkable work on measurement uncertainty while Hayley Jones gave a masterclass on her new method for meta-analysis of test accuracy across multiple thresholds. I presented on the CEA of test sequences (available here). Simon Walker and James Buchanan added insightful points as discussants. We had a fantastically engaged audience, with great questions and comments. It shows that the CEA of diagnostic tests is becoming a hugely important topic.

Sadly, some other morning sessions were not as well attended. One session, also on CEA, was even cancelled due to lack of audience! For future conferences, I’d suggest scheduling the sessions on the day after the conference dinner a bit later, as well as having fewer sessions to choose from.

Next up on my agenda was the exceptional session on equity, chaired by Paula Lorgelly, and with presentations by Richard Cookson, Susan Griffin and Ijeoma Edoka. I was unable to attend, but I have watched it at home via YouTube (from 1:57:10)! That’s right, some sessions were live streamed and are still available via the iHEA website. Do have a look!

My last session of the conference was on end-of-life care, with Charles Normand chairing, discussed by Helen Mason, Eric Finkelstein, and Mendwas Dzingina, and presentations by Koonal Shah, Bridget Johnson and Nikki McCaffrey. It was a really thought-provoking session, raising questions on the value of interventions at the end-of-life compared to at other stages of the life course.

Lastly, the outstanding plenary session by Lise Rochaix and Joseph Kutzin on how to translate health economics research into policy. Lise and Joseph had pragmatic suggestions and insightful comments on the communication of health economics research to policy makers. Superb! Also available on the live stream here (from 06:09:44).

iHEA 2019 was truly an amazing conference. Expertly organised, well thought-out and with lots of interesting sessions to choose from. iHEA 2021 in Cape Town is firmly in my diary!