Thesis Thursday: Cheryl Jones

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 Cheryl Jones who has a PhD from the University of Manchester. If you would like to suggest a candidate for an upcoming Thesis Thursday, get in touch.

Title
The economics of presenteeism in the context of rheumatoid arthritis, ankylosing spondylitis and psoriatic arthritis
Supervisors
Katherine Payne, Suzanne Verstappen, Brenda Gannon
Repository link
https://www.research.manchester.ac.uk/portal/en/theses/the-economics-of-presenteeism-in-the-context-of-rheumatoid-arthritis-ankylosing-spondylitis-and-psoriatic-arthritis%288215e79a-925e-4664-9a3c-3fd42d643528%29.html

What attracted you to studying health-related presenteeism?

I was attracted to study presenteeism because it gave me a chance to address both normative and positive issues. Presenteeism, a concept related to productivity, is a controversial topic in the economic evaluation of healthcare technologies and is currently excluded from health economic evaluations, following the recommendation made by the NICE reference case. The reasons why productivity is excluded from economic evaluations are important and valid, however, there are some circumstances where excluding productivity is difficult to defend. Presenteeism offered an opportunity for me to explore and question the social value judgements that underpin economic evaluation methods with respect to productivity. In terms of positive issues related to presenteeism, research into the development of methods that can be used to measure and value presenteeism was (and still is) limited. This provided an opportunity to think creatively about the types of methods we could use, both quantitative and qualitative, to address and further methods for quantifying presenteeism.

Are existing tools adequate for measuring and valuing presenteeism in inflammatory arthritic conditions?

That is the question! Research into methods that can be used to quantify presenteeism is still in its infancy. Presenteeism is difficult to measure accurately because there are a lack of objective measures that can be used, for example, the number of cars assembled per day. As a consequence, many methods rely on self-report surveys, which tend to suffer from bias, such as reporting or recall bias. Methods that have been used to value presenteeism have largely focused on valuing presenteeism as a cost using the human capital approach (HCA: volume of presenteeism multiplied by a monetary factor). The monetary factor typically used to convert the volume of presenteeism into a cost value is wages. Valuing productivity using wages risks taking account of discriminatory factors that are associated with wages, such as age. There are also economic arguments that question whether the value of the wage truly reflects the value of productivity. My PhD focused on developing a method that values presenteeism as a non-monetary benefit, thereby avoiding the need to value it as a cost using wages. Overall, methods to measure and value presenteeism still have some way to go before a ‘gold standard’ can be established, however, there are many experts from many disciplines who are working to improve these methods.

Why was it important to conduct qualitative interviews as part of your research?

The quantitative component of my PhD was to develop an algorithm, using mapping methods, that links presenteeism with health status and capability measures. A study by Connolly et al. recommend conducting qualitative interviews to provide some evidence of face/content validity to establish whether a quantitative link between two measures (or concepts) is feasible and potentially valid. The qualitative study I conducted was designed to understand the extent to which the EQ-5D-5L, SF6D and ICECAP-C were able to capture those aspects of rheumatic conditions that negatively impact presenteeism. The results suggested that all three measures were able to capture those important aspects of rheumatic conditions that affect presenteeism; however, the results indicated that the SF6D would most likely be the most appropriate measure. The results from the quantitative mapping study identified the SF6D as the most suitable outcome measure able to predict presenteeism in working populations with rheumatic conditions. The advantage of the qualitative results was that it provided some evidence that explained why the SF6D was the more suitable measure rather than relying on speculation.

Is it feasible to predict presenteeism using outcome measures within economic evaluation?

I developed an algorithm that links presenteeism, measured using the Work Activity Productivity Impairment (WPAI) questionnaire, with health and capability. Health status was measured using the EQ-5D-5L and SF6D, and capability was measured using the ICECAP-A. The SF6D was identified as the most suitable measure to predict presenteeism in a population of employees with rheumatoid arthritis or ankylosing spondylitis. The results indicate that it is possible to predict presenteeism using generic outcome measures; however, the results have yet to be externally validated. The qualitative interviews provided evidence as to why the SF6D was the better predictor for presenteeism and the result gave rise to questions about the suitability of outcome measures given a specific population. The results indicate that it is potentially feasible to predict presenteeism using outcome measures.

What would be your key recommendation to a researcher hoping to capture the impact of an intervention on presenteeism?

Due to the lack of a ‘gold standard’ method for capturing the impact of presenteeism, I would recommend that the researcher reports and justifies their selection of the following:

  1. Provide a rationale that explains why presenteeism is an important factor that needs to be considered in the analysis.
  2. Explain how and why presenteeism will be captured and included in the analysis; as a cost, monetary benefit, or non-monetary benefit.
  3. Justify the methods used to measure and value presenteeism. It is important that the research clearly reports why specific tools, such as presenteeism surveys, have been selected for use.

Because there is no ‘gold standard’ method for measuring and valuing presenteeism and guidelines do not exist to inform the reporting of methods used to quantify presenteeism, it is important that the researcher reports and justifies their selection of methods used in their analysis.

Sam Watson’s journal round-up for 25th June 2018

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 efficiency of slacking off: evidence from the emergency department. Econometrica [RePEc] Published May 2018

Scheduling workers is a complex task, especially in large organisations such as hospitals. Not only should one consider when different shifts start throughout the day, but also how work is divided up over the course of each shift. Physicians, like anyone else, value their leisure time and want to go home at the end of a shift. Given how they value this leisure time, as the end of a shift approaches physicians may behave differently. This paper explores how doctors in an emergency department behave at ‘end of shift’, in particular looking at whether doctors ‘slack off’ by accepting fewer patients or tasks and also whether they rush to finish those tasks they have. Both cases can introduce inefficiency by either under-using their labour time or using resources too intensively to complete something. Immediately, from the plots of the raw data, it is possible to see a drop in patients ‘accepted’ both close to end of shift and close to the next shift beginning (if there is shift overlap). Most interestingly, after controlling for patient characteristics, time of day, and day of week, there is a decrease in the length of stay of patients accepted closer to the end of shift, which is ‘dose-dependent’ on time to end of shift. There are also marked increases in patient costs, orders, and inpatient admissions in the final hour of the shift. Assuming that only the number of patients assigned and not the type of patient changes over the course of a shift (a somewhat strong assumption despite the additional tests), then this would suggest that doctors are rushing care and potentially providing sub-optimal or inefficient care closer to the end of their shift. The paper goes on to explore optimal scheduling on the basis of the results, among other things, but ultimately shows an interesting, if not unexpected, pattern of physician behaviour. The results relate mainly to efficiency, but it’d be interesting to see how they relate to quality in the form of preventable errors.

Semiparametric estimation of longitudinal medical cost trajectory. Journal of the American Statistical Association Published 19th June 2018

Modern computational and statistical methods have opened up a range of statistical models to estimation hitherto inestimable. This includes complex latent variable structures, non-linear models, and non- and semi-parametric models. Recently we covered the use of splines for semi-parametric modelling in our Method of the Month series. Not that complexity is everything of course, but given this rich toolbox to more faithfully replicate the data generating process, one does wonder why the humble linear model estimated with OLS remains so common. Nevertheless, I digress. This paper addresses the problem of estimating the medical cost trajectory for a given disease from diagnosis to death. There are two key issues: (i) the trajectory is likely to be non-linear with costs probably increasing near death and possibly also be higher immediately after diagnosis (a U-shape), and (ii) we don’t observe the costs of those who die, i.e. there is right-censoring. Such a set-up is also applicable in other cases, for example looking at health outcomes in panel data with informative dropout. The authors model medical costs for each month post-diagnosis and time of censoring (death) by factorising their joint distribution into a marginal model for censoring and a conditional model for medical costs given the censoring time. The likelihood then has contributions from the observed medical costs and their times, and the times of the censored outcomes. We then just need to specify the individual models. For medical costs, they use a multivariate normal with mean function consisting of a bivariate spline of time and time of censoring. The time of censoring is modelled non-parametrically. This setup of the missing data problem is sometimes referred to as a pattern mixing model, in that the outcome is modelled as a mixture density over different populations dying at different times. The authors note another possibility for informative missing data, which was considered not to be estimable for complex non-linear structures, was the shared parameter model (to soon appear in another Method of the Month) that assumes outcomes and dropout are independent conditional on an underlying latent variable. This approach can be more flexible, especially in cases with varying treatment effects. One wonders if the mixed model representation of penalised splines wouldn’t fit nicely in a shared parameter framework and provide at least as good inferences. An idea for a future paper perhaps… Nevertheless, the authors illustrate their method by replicating the well-documented U-shaped costs from the time of diagnosis in patients with stage IV breast cancer.

Do environmental factors drive obesity? Evidence from international graduate students. Health Economics [PubMedPublished 21st June 2018

‘The environment’ can encompass any number of things including social interactions and networks, politics, green space, and pollution. Sometimes referred to as ‘neighbourhood effects’, the impact of the shared environment above and beyond the effect of individual risk factors is of great interest to researchers and policymakers alike. But there are a number of substantive issues that hinder estimation of neighbourhood effects. For example, social stratification into neighbourhoods likely means people living together are similar so it is difficult to compare like with like across neighbourhoods; trying to model neighbourhood choice will also, therefore, remove most of the variation in the data. Similarly, this lack of common support, i.e. overlap, between people from different neighbourhoods means estimated effects are not generalisable across the population. One way of getting around these problems is simply to randomise people to neighbourhoods. As odd as that sounds, that is what occurred in the Moving to Opportunity experiments and others. This paper takes a similar approach in trying to look at neighbourhood effects on the risk of obesity by looking at the effects of international students moving to different locales with different local obesity rates. The key identifying assumption is that the choice to move to different places is conditionally independent of the local obesity rate. This doesn’t seem a strong assumption – I’ve never heard a prospective student ask about the weight of our student body. Some analysis supports this claim. The raw data and some further modelling show a pretty strong and robust relationship between local obesity rates and weight gain of the international students. Given the complexity of the causes and correlates of obesity (see the crazy diagram in this post) it is hard to discern why certain environments contribute to obesity. The paper presents some weak evidence of differences in unhealthy behaviours between high and low obesity places – but this doesn’t quite get at the environmental link, such as whether these behaviours are shared through social networks or perhaps the structure and layout of the urban area, for example. Nevertheless, here is some strong evidence that living in an area where there are obese people means you’re more likely to become obese yourself.

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Chris Sampson’s journal round-up for 5th March 2018

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.

Healthy working days: the (positive) effect of work effort on occupational health from a human capital approach. Social Science & Medicine Published 28th February 2018

If you look at the literature on the determinants of subjective well-being (or happiness), you’ll see that unemployment is often cited as having a big negative impact. The same sometimes applies for its impact on health, but here – of course – the causality is difficult to tease apart. Then, in research that digs deeper, looking at hours worked and different types of jobs, we see less conclusive results. In this paper, the authors start by asserting that the standard approach in labour economics (on which I’m not qualified to comment) is to assume that there is a negative association between work effort and health. This study extends the framework by allowing for positive effects of work that are related to individuals’ characteristics and working conditions, and where health is determined in a Grossman-style model of health capital that accounts for work effort in the rate of health depreciation. This model is used to examine health as a function of work effort (as indicated by hours worked) in a single wave of the European Working Conditions Survey (EWCS) from 2010 for 15 EU member states. Key items from the EWCS included in this study are questions such as “does your work affect your health or not?”, “how is your health in general?”, and “how many hours do you usually work per week?”. Working conditions are taken into account by looking at data on shift working and the need to wear protective equipment. One of the main findings of the study is that – with good working conditions – greater work effort can improve health. The Marxist in me is not very satisfied with this. We need to ask the question, compared to what? Working fewer hours? For most people, that simply isn’t an option. Aren’t the people who work fewer hours the people who can afford to work fewer hours? No attention is given to the sociological aspects of employment, which are clearly important. The study also shows that overworking or having poorer working conditions reduces health. We also see that, for many groups, longer hours do not negatively impact on health until we reach around 120 hours a week. This fails a good sense check. Who are these people?! I’d be very interested to see if these findings hold for academics. That the key variables are self-reported undermines the conclusions somewhat, as we can expect people to adjust their expectations about work effort and health in accordance with their colleagues. It would be very difficult to avoid a type 2 error (with respect to the negative impact of effort on health) using these variables to represent health and the role of work effort.

Agreement between retrospectively and contemporaneously collected patient-reported outcome measures (PROMs) in hip and knee replacement patients. Quality of Life Research [PubMed] Published 26th February 2018

The use of patient-reported outcomes (PROMs) in elective care in the NHS has been a boon for researchers in our field, providing before-and-after measurement of health-related quality of life so that we can look at the impact of these interventions. But we can’t do this in emergency care because the ‘before’ is never observed – people only show up when they’re in the middle of the emergency. But what if people could accurately recall their pre-emergency health state? There’s some evidence to suggest that people can, so long as the recall period is short. This study looks at NHS PROMs data (n=443), with generic and condition-specific outcomes collected from patients having hip or knee replacements. Patients included in the study were additionally asked to recall their health state 4 weeks prior to surgery. The authors assess the extent to which the contemporary PROM measurements agree with the retrospective measurements, and the extent to which any disagreement relates to age, socioeconomic status, or the length of time to recall. There wasn’t much difference between contemporary and retrospective measurements, though patients reported slightly lower health on the retrospective questionnaires. And there weren’t any compelling differences associated with age or socioeconomic status or the length of recall. These findings are promising, suggesting that we might be able to rely on retrospective PROMs. But the elective surgery context is very different to the emergency context, and I don’t think we can expect the two types of health care to impact recollection in the same way. In this study, responses may also have been influenced by participants’ memories of completing the contemporary questionnaire, and the recall period was very short. But the only way to find out more about the validity of retrospective PROM collection is to do more of it, so hopefully we’ll see more studies asking this question.

Adaptation or recovery after health shocks? Evidence using subjective and objective health measures. Health Economics [PubMed] Published 26th February 2018

People’s expectations about their health can influence their behaviour and determine their future health, so it’s important that we understand people’s expectations and any ways in which they diverge from reality. This paper considers the effect of a health shock on people’s expectations about how long they will live. The authors focus on survival probability, measured objectively (i.e. what actually happens to these patients) and subjectively (i.e. what the patients expect), and the extent to which the latter corresponds to the former. The arguments presented are couched within the concept of hedonic adaptation. So the question is – if post-shock expectations return to pre-shock expectations after a period of time – whether this is because people are recovering from the disease or because they are moving their reference point. Data are drawn from the Health and Retirement Study. Subjective survival probability is scaled to whether individuals expect to survive for 2 years. Cancer, stroke, and myocardial infarction are the health shocks used. The analysis uses some lagged regression models, separate for each of the three diagnoses, with objective and subjective survival probability as the dependent variable. There’s a bit of a jumble of things going on in this paper, with discussions of adaptation, survival, self-assessed health, optimism, and health behaviours. So it’s a bit difficult to see the wood for the trees. But the authors find the effect they’re looking for. Objective survival probability is negatively affected by a health shock, as is subjective survival probability. But then subjective survival starts to return to pre-shock trends whereas objective survival does not. The authors use this finding to suggest that there is adaptation. I’m not sure about this interpretation. To me it seems as if subjective life expectancy is only weakly responsive to changes in objective life expectancy. The findings seem to have more to do with how people process information about their probability of survival than with how they adapt to a situation. So while this is an interesting study about how people process changes in survival probability, I’m not sure what it has to do with adaptation.

3L, 5L, what the L? A NICE conundrum. PharmacoEconomics [PubMed] Published 26th February 2018

In my last round-up, I said I was going to write a follow-up blog post to an editorial on the EQ-5D-5L. I didn’t get round to it, but that’s probably best as there has since been a flurry of other editorials and commentaries on the subject. Here’s one of them. This commentary considers the perspective of NICE in deciding whether to support the use of the EQ-5D-5L and its English value set. The authors point out the differences between the 3L and 5L, namely the descriptive systems and the value sets. Examples of the 5L descriptive system’s advantages are provided: a reduced ceiling effect, reduced clustering, better discriminative ability, and the benefits of doing away with the ‘confined to bed’ level of the mobility domain. Great! On to the value set. There are lots of differences here, with 3 main causes: the data, the preference elicitation methods, and the modelling methods. We can’t immediately determine whether these differences are improvements or not. The authors stress the point that any differences observed will be in large part due to quirks in the original 3L value set rather than in the 5L value set. Nevertheless, the commentary is broadly supportive of a cautionary approach to 5L adoption. I’m not. Time for that follow-up blog post.

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