How Tests Make Experience Fact, Part 1

During some research activities this week, an acquaintance asked me, “What’s the most surprising thing you’ve learned about allergies so far?” The first thing that came to mind was how unreliable the tests – especially blood tests – are for definitively proving someone has an allergy. That is not to say that tests aren’t useful: I’ve witnessed physicians use both blood and skin allergy testing to confirm suspected allergies. These tests give peace of mind to the patient and reinforce the diagnosis for the physician. But they are not the only factor considered for making an allergy diagnosis, especially for food allergies. Patient histories matter a lot, too.

Allergy skin testing apparatus
Allergy skin testing apparatus.

In my home discipline of Science and Technology Studies (STS), researchers have thought a lot about the role of tests and experiments in making phenomena in the world into scientific facts. French philosopher/social scientist/champion of the field Bruno Latour opened up this question in his early observational studies of how scientists do scientific work in the lab. The perspective in his first book, roughly, is that the papers produced in the lab, including notes, graphs, print-outs from machines, and finished scientific papers, help to organize and contextualize measurements of stuff in the world. Once all those measurements are organized, scientific papers present them as facts that pre-exist attempts to measure them.

Many scientists have been upset by Latour’s view. In the 1990s, scientists and STS scholars exchanged a series of heated papers about whether this perspective had any value at all. Some (myself included when I started out in grad school!) thought that Latour is suggesting that facts are “made up” in the sense that they are not real and that scientists are hoodwinking the public. That is not how experienced social scientists understand it, though. The intention, as I understand it now, is to describe the process by which scientists are trained to collect information and present it as fact, not to cast doubt on whether the facts they present are “real” or “fake.”Social science is mainly a descriptive endeavor, and STS, as a social science, conforms to this archetype.

What’s so interesting about the role of testing in diagnosing allergies is that it is not the ONLY tool allergists use to make a patient’s allergies “fact.” They also rely heavily on the patient’s history: recollections of allergic reactions, other symptoms and illnesses that occurred around the time of past reactions, memories of what was eaten or touched before the reaction, and so on. Taking a good history is just as specialized a skill as conducting complex experiments. As medical students and residents, doctors-in-training learn the questions to ask, the answers to watch out for, the tests that should be used to follow up on particular symptoms, and how to fit sets of symptoms together into different diagnoses.

Even though taking a medical history is a highly specialized kind of skill, it offers a different kind of evidence from what a doctor learns by sending off a vial of blood to measure certain values through testing. For one, it assumes that the patient’s memory of events is true. There is implicitly a high degree of trust between the doctor and patient that would be necessary to do a blood draw: the patient trusts the doctor enough to tell the truth and puts in the effort to remember minor details that the doctor asks them about, and the doctor trusts the patient enough to assume they’re telling the truth. Finally, there are no precise numerical measurements that come out of a history; it’s a story to be interpreted rather than a number to be compared to the “normal” range of values.

I find the way that patient histories and tests work together in allergy diagnosis fascinating. For the doctors I’ve spoken with, neither tool can stand on its own. Allergists who are active as food allergy advocates and educators also stress this point. This recent video, featuring Dr. Scott Sicherer from the Mount Sinai Jaffe Food Allergy Institute, is an example of how doctors talk about testing as just one part of the process of diagnosing food allergies. Together, histories and tests they offer the needed evidence to diagnose allergy – to make the patient’s experience of allergy a medical fact.

In a few days, I will post a second short essay about how social scientists and philosophers think about the role of patient experience in medicine and how that relates to food allergy. Stay tuned!

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