Thesis Thursday: Koh Jun Ong

On the third Thursday of every month, we speak to a recent graduate about their thesis and their studies. This month’s guest is Dr Koh Jun Ong who has a PhD from the University of Groningen. If you would like to suggest a candidate for an upcoming Thesis Thursday, get in touch.

Title
Economic aspects of public health programmes for infectious disease control: studies on human immunodeficiency virus & human papillomavirus
Supervisors
Maarten Postma, Mark Jit
Repository link
http://hdl.handle.net/11370/0edbcfae-2a0c-4103-9722-fb8086d75cff

Which public health programmes did you consider in your research?

Three public health programmes were considered in the thesis: 1) HIV Pre-Exposure Prophylaxis (PrEP), 2) Human Papillomavirus (HPV) vaccination, and 3) HIV screening to reduce undiagnosed infections in the population.

The first two of the three involved primary infectious disease prevention among men who have sex with men (MSM), and both of these programmes were to be delivered via sexual health clinics in England (commonly known as genitourinary medicine, GUM, clinics).

The third public health infectious disease control programme involved secondary prevention of onward HIV transmission in the general population by encouraging routine HIV screening to reduce undiagnosed HIV, with a view of earlier diagnosis leading to antiretroviral treatment initiation, which will stop HIV transmission with viral suppression.

Was it necessary to develop complex mathematical models?

It depends on the policy research question. A dynamic model was used for the HPV vaccination research question, which captures the ecological externality that vaccination provides by reducing transmission to non-vaccinees. A dynamic model was used because this programme would likely reach a high proportion of MSM who attend GUM clinics in England, and therefore the subsequent knock-on impact of disease transmission in the population was likely to be substantial.

The policy research question was different for PrEP and a static model was more suitable since the objective was to advise NHS England on whether and how such a programme, with relatively small numbers of patients over an initial time-limited period, may represent value for money in England. We first considered a public health control programme, with promising new efficacy data from the 500-person PrEP pilot study (the UK-based PROUD trial) and additional information from per protocol participants in the earlier iPrEx study. The initial consideration was to maintain the preventative effect of a drug that needs to be taken on a daily basis (compared with near one-off HPV vaccination – three doses in total delivered within a year’s time). Regular monitoring of STI and patient’s renal function meant there were clinical service capacity issue to consider, which was likely to limit access initially. Thus, a static model that did not take into account transmission was used.

However, dynamic modelling would be useful to inform policy decisions as PrEP usage expands. Firstly, because it would then be important to capture the indirect effect on infection transmission. Secondly, because when the force of infection begins to fall as incidence declines, dynamic modelling will inform future delivery of a programme that maintains its value. These represent important areas for future research.

Finally, the model designed for the research question on HIV screening was quite straightforward as its aim is primarily to advise local commissioners on financial implications of offering routine screening in their local area, which is dependent on local clinical resources and local disease prevalence.

Did you draw any important conclusions from your literature reviews?

Two literature reviews were conducted: 1) a review on economic parameters i.e. cost and utility estimates for HPV-related outcomes, and 2) a review on published MSM HPV vaccination economic evaluations.

In relation to the first review, most economic models of HPV-related interventions selected economic parameters in a pretty ad hoc way, without reviewing the entirety of the literature. We found substantial variations in cost and utility estimates for all diseases considered in our systematic review, wherever there were more than one publication. These variations in value estimates could result from the differences in cancer site, disease stages, study population, treatment pathway/settings, treatment country and utility elicitation methods used. It would be important for future models to be transparent about parameter sources and assumptions, and to recognise that as patient disease management changes over time, there will be corresponding effects on both cost and utility, necessitating future updates to the estimates. These must be considered when applied to future economic evaluations, to ensure that assumptions are up-to-date and closely reflect the case mix of patients being evaluated.

In relation to the second review, despite limited models, different modelling approaches and assumptions, a general theme from these studies reveal modelling outcomes to be most sensitive to assumptions around vaccine efficacy and price. Future studies could consider synchronising parameter assumptions to test outputs generated by different models.

What can your research tell us about the ‘cost-effective but unaffordable’ paradox?

A key finding and concluding remark of this thesis was that “findings around cost-effectiveness should not be considered independently of budget impact and affordability considerations, as the two are interlinked”. Ultimately, cost-effectiveness is linked to the budget and, in an ideal world, a cost-effectiveness threshold should correspond to the opportunity cost of replacing least cost-effective care at the margin of the whole healthcare budget spend. This willingness to pay threshold should be linked to the amount of budgetary resources an intervention displaces. After all, the concept of opportunity cost in a fixed budget setting means that decisions to invest in something translates to funding being displaced elsewhere.

Since most health economies do not have unlimited resources, even if investment in a new intervention gives high returns and therefore is worthwhile from a value for money perspective, without the necessary resources it cannot always be afforded despite its high return on investment. Having a limited budget means that funding an expensive new intervention may mean moving funding away from existing services, which may be more cost-effective than the new intervention. Hence, the services from which funds are moved from will lose out, and this may leave society worse-off.

A simple analogy may be that buying a property that guarantees return over a defined period is worthwhile, but if I cannot afford it in the first place, is this still an option?

This was clearly demonstrated in the PrEP example, where despite potential to be cost-effective, the high cost of the intervention at list price carried with it a very high budget impact. The size of the population needed to be given PrEP to achieve substantial public health benefits is large, which meant that a public health programme could pose an affordability challenge to the national health care system.

Based on your findings, how might HIV and HPV prevention strategies be made more cost-effective?

Two strategies could influence cost effectiveness: optimizing the population covered and using an appropriate comparator price.

The most obvious way to improve cost-effectiveness is to optimise the population covered. For example, we know that HIV risk, as measured by HIV incidence, is higher among GUM-attending MSM. Therefore, delivering a PrEP programme to this population (at least in the initial phase until the intervention becomes more affordable) will likely result in a higher number of new HIV infections prevented. Similarly, HIV screening offered to areas with high local prevalence would likely give a higher number of new diagnoses.

The other important factor to consider around cost-effectiveness is the comparator price on which the technology appraisal is based. In the chapter on estimating HIV care cost in England, we demonstrated that with imminent availability of generic antiretrovirals, the lifetime care cost for a person living with HIV will reduce substantially. This reduced cost, representing cost of care with existing intervention, should be used as comparator for newer HIV interventions, as they would represent what society will be paying in the absence of the new interventions, allowing corresponding reduced price expectations for new interventions to ensure cost-effectiveness is maintained.

How did you find the experience of completing your thesis by publication?

It was brilliant! I must acknowledge all the contributions from my supervisors and co-authors in making this possible and for the very positive experience of this process. A major advantage of doing a PhD by publication is that the work conducted was regularly peer-reviewed, hence providing an extra check of the robustness of the analyses. And also the fact that these works are out for public consumption almost immediately, making the science available for other researchers to consider and to move the science to the next stage.

Agent relationships and information asymmetries in public health

The agent relationship and information asymmetry are two features of healthcare economics – but how do they apply to public health policy around processed foods?

Why is health different to other goods?

Arrow’s 1963 seminal paper helped lay the foundations for health economics as a discipline. The Nobel-winning economist talks about what makes healthcare different to other types of market goods. Two of the principal things are agent relationship – that a clinician often makes choices on behalf of a patient (Arrow calls them a “controlling agent”); and information asymmetry – that a clinician knows more than the patient (“informational inequality”). Whereas if someone is buying a new car, they make their own choices, and they might read up on the extensive information available so that they are reasonably knowledgeable about what to buy. These two factors have evolved and possibly diminished over time, especially among highly educated people in developed countries; people often have more choice over their treatment options, and some people have become ‘expert patients‘. Patients may no longer believe that the Götter in Weiß (Gods dressed in white) always know best.

Agent relationship and information asymmetry are features of healthcare economics but they also apply to public health economics. But where people accept clinicians as having more knowledge or acting as their agent, people don’t always accept advice on food from public health policy makers in the same way. People may think, “well I know how to buy a bottle of beer, or a can of coke, or a pizza”, and may not see any potential information asymmetry. Some of it might be ‘akrasia’ – they know that food is unhealthy, but they eat it anyway because it is delicious! However, few people may be aware that poor diet and obesity are the biggest risk factors for ill health and mortality in England.

People might ask “why should a nanny state agent make my food or drink decisions for me?” Of course, this is ignoring the fact that processed food companies might be making those decisions, and reinforcing them using huge marketing budgets. Consumers see government influences but they don’t always see the other information asymmetry and agent relationship; the latent power structures that drive their behaviours – from the food, drinks, alcohol industry, etc. Unsustainable food systems that promote obesity and poor health might be an example of market failure or a tragedy of the commons. The English food system has not moved on enough from post-world war 2 rationing, where food security was the major concern; it still has an objective to maximise calorie supply across the population, rather than maximise population health.

Some of the big UK misselling scandals like mortgage PPI are asymmetries. You could argue that processed foods (junk food high in salt, sugar and saturated fats) might be missold because producers try to misrepresent the true mix of ingredients – for example, many advertisements for processed foods try to misrepresent their products by showing lots of fresh fruit and vegetables. Even though processed foods might have ingredients listed, people have an information asymmetry (or at least, a deficit around information processing) around truly understanding the amount of hidden salt and sugars, because they may assume that the preparation process is similar to a familiar home cooked method. In the US there have been several lawsuits from consumers alleging that companies have misled them by promoting products as being wholesome and natural when they are in fact loaded with added sugars.

The agent relationship and information asymmetry as applied to food policy and health.

How acceptable are public health policies?

A 2012 UK poll carried out by YouGov, funded by the Adam Smith Institute (a right wing free market think tank), found that 22% of people in England thought that the government should tell people what to eat and drink, and 44% thought the government should not. Does this indicate a lack of respect for public health as a specialism? But telling people what to eat and drink is not the same as enacting structural policies to improve foods. Research has shown that interventions like reducing salt in processed foods in the UK or added sugar labelling in the US could be very cost effective. There has been some progress with US and UK programmes like the sugary drinks industry levy, which now has a good level of public support. But voluntary initiatives like the UK sugar reduction programme have been less effective, which may be because they are weakly enforced, and not ambitious enough.

A recent UK study used another YouGov survey to assess the public acceptability of behavioural ‘nudge’ interventions around tobacco, alcohol, and high-calorie snack foods. It compared four types of nudges: labelling (adding graphic warning labels to products); size (reducing pack size of snacks, serving size for alcohol, and number of cigarettes in packets for tobacco); tax (increasing the price to consumers); and availability (banning sales from corner shops). This study found that labelling was the most acceptable policy, then size, tax, and availability. It found that targeting tobacco use was more acceptable than targeting alcohol or food. Acceptability was lower in people who participated in the relevant behaviour regularly, i.e. smokers, heavy drinkers, frequent snackers.

What should public health experts do?

Perhaps public health experts need to do more to enhance their reputation with the public. But when they are competing with a partnership between right wing think tanks, the media and politicians, all funded by big food, tobacco and alcohol, it is difficult for public health experts to get their message out. Perhaps it falls to celebrities and TV chefs like Jamie Oliver and Hugh Fearnley-Whittingstall to push for healthy (and often more sustainable) food policy, or fiscal measures to internalise the externalities around unhealthy foods. The food industry falls back on saying that obesity is complex, exercise is important as well as diet, and more research is needed. They are right that obesity is complex, but there is enough evidence to act. There is good evidence for an ‘equity effectiveness hierarchy‘ where policy-level interventions are more effective at a population level, and more likely to reduce inequalities between rich and poor, than individual, agentic interventions. This means that individual education and promoting exercise may not be as effective as national policy interventions around food.

The answer to these issues may be in doing more to reduce information asymmetries by educating the public about what is in processed food, starting with schools. At the same time understanding that industries are not benevolent; they have an agent relationship in deciding what is in the foods that arrive at our tables, and the main objectives for their shareholders are that food is cheap, palatable, and with a long shelf life. Healthy comes lower on the list of priorities. Government action is needed to set standards for foods or make unhealthy foods more expensive and harder to buy on impulse, and restrict marketing, as previously done with other harmful commodities such as tobacco.

In conclusion, there are hidden agent relationships and information asymmetries around public health policies, for instance around healthy food and drinks. Public health can potentially learn from economic instruments that have been used in other industries to mitigate information asymmetries and agent relationships. If Government and the food industry had shared incentives to create a healthier population then good things might happen. I would be curious to know what others think about this!

Brendan Collins’s journal round-up for 22nd July 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.

Making hard choices in local public health spending with a cost-benefit analysis approach. Frontiers in Public Health Published 29th June 2019

In this round-up I have chosen three papers which look broadly at public health economics.

While NHS healthcare funding has been relatively preserved in the UK (in financial terms at least, though not keeping up with demographic change), funding for local government public health departments has been cut. These departments commission early years services, smoking cessation, drug and alcohol treatment, sexual health, and lots of other services. A recent working paper suggests that marginal changes in Public Health funding produce a more favourable ICER than changes in NHS funding.

This is a neat paper looking at the cost-benefit for a subset of £14 million investment in public health programmes in Dorset, a county on the south coast of England, whose population is slightly older and more affluent than the England average. I try to go to Dorset every year, it has beautiful beaches with traditional Punch and Judy shows, and nice old towns where you can get out on a mackerel fishing trip.

This paper looks at the potential financial savings for each public health programme across different sectors of the economy. One of the big issues with public health as opposed to clinical interventions is the cross sector flow problem – you spend money on drug and alcohol treatment, but the majority of benefits are through prevented crime; or you prevent teenage pregnancy, and a lot of the benefits are to the welfare system (because women delay pregnancy until they are more likely to be in a stable relationship and working). This makes it hard when local councillors might say, ‘what’s in it for us?’

Figure 2 in this paper shows the cross sector flow issue clearly – the spend comes from local authority public health, but 94% of the financial benefits are in the NHS.

I think this study has a good blueprint that other local authorities could follow. The study applies an optimism bias reduction, so it is not just assuming that programmes will be as effective as the research evidence suggests. This is important as there may be a big drop off in effectiveness when something is implemented locally. Of course, sometimes local implementation might be more effective. But it would be nice to see this kind of study carried out with more real-world data. Although the optimism bias reduction makes it less likely to overestimate the cost-benefit, it doesn’t necessarily make the estimate any more precise. National outcomes data collection for public health programmes is weak or absent; better data collection might mean more evidence that prevention interventions provide value for money.

Impact of sugar‐sweetened beverage taxes on purchases and dietary intake: systematic review and meta‐analysis. Obesity Reviews [PubMed] Published 19th June 2019

A lot of health economics focuses on healthcare interventions. But, upstream, structural policy interventions have the capacity to be a lot more cost effective in preventing ill health. Sugary drinks (sugar sweetened beverages – SSBs) are a source of excess empty calories and increase the risk of cardiovascular disease, diabetes and early death. One of the first pieces of work I did as a grown-up academic was looking at a sugary drinks tax, which resulted in me getting up early one day and seeing this. At the time I thought it had roughly zero chance of being implemented. But the sugary drinks industry levy (SDIL) was implemented in the UK in April last year, and had a huge effect in terms of motivating the industry to reformulate below the thresholds of 5g and 8g of sugar per 100ml. Milk-based drinks like Frijj and Yazoo are exempt and still often have nearly 10g sugar per 100ml so there has been talk of extending the tax to these drinks. But Boris Johnson, the likely next UK Prime Minister, has come out against these ‘nanny state’ ‘sin taxes’ and said he will review them, seemingly despite there being a large scale evaluation of the SDIL, and a growing evidence base. There is a good twitter thread on this by Adam Briggs here.

Policies like the SDIL rely on price elasticity of demand (PED). But this PED varies depending, for instance, on how addictive something is and the availability of substitutes. For tobacco, because it is addictive, a 10% price increase might only produce a 5% reduction in demand.

This systematic review and meta-analysis looked at data from 17 studies in 6 jurisdictions and found that, on average, sugar consumption is unit elastic – a 10% price increase produces a 10% reduction in purchases. However, there was considerable variation between studies. The authors designed a bespoke risk of bias tool for this, as the traditional tools used for health interventions did not include all of the potential biases for an SSB tax evaluation; this checklist may be useful for future analyses of similar policies.

If the SSB duty produced a unit elastic response in the UK, it means that people aren’t spending more on SSBs, they are merely buying less of something that they don’t need and which damages their health. And maybe a few people, over many years, consume a bit less sugar, don’t get type 2 diabetes, don’t have to give up work, and are actually better off and can provide for their families for a bit longer. Of course, in the UK the picture is complex because of the different tiers of the duty, but reformulation has meant that people are consuming less sugar even if they don’t reduce their sugary drink consumption. Also, the revenue from the SDIL is spent on healthier schools, so it could be argued that the policy is a win-win.

The cost of not breastfeeding: global results from a new tool. Health Policy & Planning [PubMed] Published 24th June 2019

This study looks at the potential worldwide cost savings if breastfeeding rates were improved. Breastfeeding prevents cases of diarrhoea, obesity, maternal cancer, and other diseases and adverse outcomes. Low breastfeeding rates are a big problem in developing countries where formula costs a huge proportion of income (nearly 20% of average household income in India and Pakistan according to this paper) and water supplies may be contaminated. This study includes healthcare costs, and economic losses from early deaths and reduced IQ through sub-optimal breastfeeding, which total $341 billion per year worldwide.

The authors have said there is also going to be an online, and Excel-based, results tool.

I love reading such ambitious studies that cover the whole world. Producing worldwide estimates for costs is a difficult exercise and can have a danger of losing meaning. For instance, in developing countries, medical costs may be very low if health coverage is very sparse. If a country doesn’t spend anything on healthcare and you measure public health interventions in healthcare cost savings, then it looks like these public health interventions are not worth doing. That is why it is sometimes better to focus on DALYs (and potentially put a financial value on them, although this can be controversial) rather than financial costs. The study found the biggest absolute costs of not breastfeeding were in North America ($115bn), while biggest costs as a proportion of gross national income (GNI) were for sub-Saharan Africa, where not breastfeeding cost 2.6% of GNI.

It looks like two out of the three authors are men. Is there a problem with men being pro-breastfeeding? Why should a man tell women what to do with their bodies? Women shouldn’t feel stigmatised about their infant feeding choices. But for me it is not about telling women what to do. It is making sure the structures and social norms are there to support breastfeeding and that formula companies are regulated in how they market themselves and their products. Maybe men not caring enough about breastfeeding is what has got us to where we are now. 

Credits