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Do androids dream of EQ-5D?

NB: spoiler alert!

There are many interpretations of the meaning, themes, and philosophical explorations of the film Blade Runner. A neglected reading is that it analyses in science fiction form the EQ-5D. It investigates its rationale, aims, and even methods for valuing health states.

If you are a member of the EuroQol group, this will be obvious, but if not you may ask “What’s that going to prove?”. Indulge me.

Analysing QALYs: years in pain

Some way through the film, Dr Eldon Tyrell explains QALYs to Roy Batty with a neat analogy: “The light that burns twice as bright burns half as long”. By this, he means that a year in perfect health is the equivalent of two years in a health state valued at half the value of a year in perfect health. Dr Tyrell adds a further point, relevant to the economic theory lying behind valuation methods such as the time trade-off (TTO), that there may sometimes be a trade-off between length and quality of life. He points out to Roy that he has burned very, very brightly, to compensate for the fact that he has such a short life span.

Unfortunately, Roy is not impressed by these arguments and crushes Dr Tyrell’s skull with his bare hands. The film is clearly not only explaining the QALY concept and the TTO method, but also illustrating the problem that it is difficult to convince some people of their merits.

The film also offers a perspective on the debates around the assertion that a QALY is a QALY is a QALY. It reveals that the Tyrell Corporation’s motto is ‘More Human Than Human’. Is it possible to generate more than one QALY per year? Assuming a normal human Los Angeles life expectancy in good health of 72 years, NEXUS 6 replicants’ four-year life span would need to generate 18 QALYs per year for equivalence. Perhaps for some special people that is true. The point made is that such arguments are as confused, confusing, and empty as many of the points made by academics in the Q=Q=Q literature.

EQ-5D dimensions and levels: give me four… and noodles

The film dissects a feature of the EQ-5D descriptive system, the thresholds between different levels within dimensions. Are they sufficiently discriminatory? Do people have different thresholds? For example, medical experts often think that too many people record “No pain” for a condition that they like to treat. (Incidentally, this is often mistakenly called a ‘ceiling effect’, when it is actually the depth of the floor rather than the height of the ceiling that matters. The film brilliantly exposes this error using its distinctive cityscape. Towering buildings house corporate offices and rich people’s apartments, but what affects most people’s quality of life is not the height of these but the depth of squalor at street level.)

In the film, a sub-group of the population is shown to have an apparent extreme pain threshold. Pris puts her hand in boiling water to fish out a cooked egg, Leon puts his hand into a sub-zero freezing mixture to fish out an eyeball, and Roy breaks through a bathroom wall with his head, none of them flinching. So, a high pain threshold? But when he’s been twice hit by Deckard with a lead pipe, Roy says “That hurt!” and also sticks a metal spike through his hand as a shock to prevent his body from shutting down before death. Similarly, Bryant tells Deckard that the only way you can hurt Leon is to kill him. But Leon experiences extreme discomfort from having an itch you can never scratch. Such ambiguities highlight some of the problems faced in creating the EQ-5D descriptive system.

The deliberate vagueness of the term usual activities implies work and leisure activities are equivalent in that dimension. Replicants’ work activities include lifting 400-pound atomic loads all day and night, being part of an off-world kick murder squad, and engaging in combat both off the shoulder of Orion and near the Tannhäuser Gate. Leisure activities seem limited to, for example, seeing things you people wouldn’t believe such as C-beams glittering in the dark. The equivalence of these with the usual activities of ordinary people is not obvious, so the film warns us to interpret this dimension cautiously.

The importance of including both physical and mental health is cleverly dealt with by both Roy and Leon invoking fear, similar to anxiety. Roy asks Deckard “Quite an experience to live in fear, isn’t it?”, implicitly comparing feelings about his general quality of life with Deckard’s current health state, which is hanging from a beam at the top of a tall building with two broken fingers and an apparent psychopath leaning over him. Roy may be physically perfect, but his mental health is not. Leon makes a similar comparison while attempting to kill Deckard with extreme violence. But Leon says “Painful to live in fear, isn’t it?”, alluding to another descriptive system issue: whether it is truly possible to make the different dimensions independent of each other.

EQ-5D versions: towards the EQ-5D-R

Strictly speaking, of course, no replicant should be given the EQ-5D-3L or -5L. Their four-year lifespan means they are all aged 0-3. For such ages, EuroQol doesn’t even recommend the EQ-5D-Y proxy version [PDF], despite replicants being at least equal in intelligence to the genetic engineers that created them. This paradox is shown by Roy’s first comment when meeting J F Sebastian, saying how nice his toys are, then showing J F how to checkmate chess expert Dr Tyrell in two moves. This raises the question of which EQ-5D version is suitable for which groups of people and the criteria for deciding that. Should replicants be given a version suitable for young people, as they are less than four years from inception? Or for old people, because they are less than four years from death due to accelerated decrepitude? Should the criterion actually be their ability to understand the questionnaire, which is testable? Or should there be a new version, the EQ-5D-R?

An alternative to this last possibility is raised further by the film, based on the motto ‘More human than human’. Should the dimensions that are relevant to more-than-humans be restricted to those applicable to humans? Or should there be auxiliary dimensions for replicants covering other aspects of their quality of life? This is a coded discussion of the EuroQol Research Foundation’s bolt-on research programme. (This label subtly hints at the filmic Frankenstein’s Monster nature of the resulting health measure, a different kind of artificial life.) An obvious bolt-on candidate is the ability to access family photographs, precious to replicants, probably less important to humans.

Health state valuation: is this to be an empathy test?

The most philosophical issues raised by Blade Runner relate to the valuation of health states rather than their description. The film asks about the nature of humanity and the meaning and value of life, in exactly the same way as the EQ-5D does in its production of value sets.

The film uses a clever device to discuss the nature of the ‘preferences’ assumed to underlie these values. An extreme view is that people already have preferences that conform to expected utility theory (EUT) according to the axioms outlined by von Neumann & Morgenstern. So, valuation studies extract these preferences from participants’ heads. The other extreme is that people do not have any such preferences. Valuation methods are tools for constructing preferences to a researcher-defined blueprint.

The film discusses this in the form of ‘implanted memories’, which fool replicants into thinking that they have a childhood history. Does it matter if memories are real or implanted? Implanted memories serve the same purpose as real ones, helping to control emotions and intellectual functioning. In the same way, it doesn’t matter if valuation methods are constructing people’s preferences rather than mining them from brains. The values produced are still useful numbers. In fact, they are more useful, because they have mathematical properties that normal people’s preferences don’t have.

Rachael is initially distressed at learning that her memory of spider cannibalism is fake but she comes to terms with it. This suggests that acknowledging that valuation study values are determined by valuation methods is painful but ultimately not important if this does a man’s job.

The most transparent device for discussing this is the Voight-Kampff (V-K) test, a machine used by Blade Runners to distinguish replicants from humans based on emotional responses to questions and scenarios. The analogy with the EQ-VT (EuroQol Valuation Technology) is evident. It could easily be called the EQ-VK.

There is a more subtle aspect to the way that the V-K test is used. If someone fails the V-K test on Earth because they don’t conform to normal human patterns of emotions, the Blade Runner must retire them. In the same way, if a person’s responses to valuation questions don’t conform to the patterns that researchers believe are normal – such non-human features as inconsistency and extreme aversion to bad health – their data are also retired.

Valuation study participants are not told about this, perhaps for fear that they might respond in the same way as Leon when he realised that Holden had figured out that he was failing the test. Even more subtly, it raises a difficult question. Is EUT a human way of thinking? There is of course no evidence that it is. So, a way of detecting replicants might be to see if they act according to EUT.

The role of death in health state valuation: time to die

There are too many other parallels between the world of Blade Runner and the EuroQol enterprise to cover here, but we should not neglect the key phrase “Time to die”. This is used both by Roy and Leon, but in different ways: Roy to announce his own natural death, Leon to forecast (inaccurately) Deckard’s violent death. This mirrors the dual role of death, dead and dying in valuation studies, especially those using the TTO. Survey respondents are offered health states for a given number of years only. In effect, that defines time to death, which may be as anxiety-provoking to respondents as it is to replicants. Even more controversially, respondents are forced to view some health states as ‘worse than dead’ by offering immediate death as an alternative to them. If you don’t like that health state, it’s time to die, with no Rachael available to prevent that by metaphorically shooting the interviewer. Or, in Leon’s case, actually shooting the interviewer.

The EuroQol Group: a golden land of opportunity and adventure

It can of course be argued that the year that the film was released (1982) was well before the inception date for the EuroQol Group and the EQ-5D. Development of the EuroQol instrument, as it was known then, began in 1987 and reached what might be called its NEXUS 5 stage in 1990, when it was first revealed to the public. Those moments should not be lost in time. But Blade Runner is a futuristic film that extrapolates from social trends in the 1980s, and the ideas and issues that permeate the EuroQol enterprise were under discussion at that time. So, it is a mark of the visionary skill of Ridley Scott and his collaborators that the film so closely matches the reality of health state measurement as it exists today.

Image courtesy of ChatGPT

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Chris Sampson
1 month ago

Some of the most convincing arguments I’ve read on this blog.

Must we also consider the important meta-metaphors regarding the release of the movie itself? Sagas in versioning and contextual adaptations? Battles for artistic and editorial control? Audience perception, legacy, and impact?

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