Before Christmas and the New Year break I was writing about how I use a biopsychosocial model in pain management – and I haven’t finished!
To review: The first post was about the context or the ideas behind Engel’s original model, and my two key clinical questions – why is this person presenting in this way at this time, and what can be done to reduce distress and disability?
The second post was about classical and operant conditioning and why these models are useful when we’re thinking about what a person does when they’re sore – and how their actions communicate to people around them. I also pointed out that many of these actions are not conscious, but have been learned and shaped from childhood, leading to a myriad of ways people express themselves when they’re in pain.
One of the criticisms of this approach to pain management is that “the model” isn’t scientific (therefore doesn’t lend itself to generating hypotheses that can be tested), and a second is that it’s “too fuzzy” and doesn’t specify what should be “in” and what should be “out” in clinical reasoning. I don’t agree with either of these statements and today I hope to present why.
Is a BPSM truly a “model”? What’s a model anyway? – one definition I’ve found is “In science, a model is a representation of an idea, an object or even a process or a system that is used to describe and explain phenomena that cannot be experienced directly.” In other words, they’re like a metaphor, bridging between something known and something abstract or unfamiliar. Models may be extremely detailed and mathematical, but may also be conceptual and broad. BPSM is probably the latter – a conceptual model from which we’ve developed some useful and testable hypotheses.
Engel himself described this as a scientific model, saying that it “enables the physician to extend application of the scientific method to aspects of everyday practice and patient care heretofore not deemed accessible to a scientific approach” (Engel, 1980, p. 535). He goes on to say that the doctor’s tasks are to find out what and how the patient is feeling, then to explanations (hypotheses) for the patient’s feelings and experiences, and then to test those hypotheses via clinical and laboratory studies (p. 536). Engel had some ideas about how a physician might generate hypotheses – based on his knowledge of general systems theory (von Bertalanffy, 1968). Engel appealed to von Bertalanffy’s idea that systems are a hierarchically arranged series of units, with the level of analysis dependent upon the complexity and unit of measure. In other words, molecular analysis is appropriate when cells and physiology are the unit of analysis, while the quality and influence of social connections are appropriate when looking at the influence of community and legislation on an individual’s behaviour.
The notion that a BPSM approach is “too fuzzy” and doesn’t provide structure is quite true: there’s not a lot of explanation as to how the various levels within a hierarchical system might interact. Interestingly, I think this problem is still relevant today! While we know a lot about the brain, and a little about the mind – we don’t know how brain produces “mind”, although some philosophers and neuroscientists have taken a stab at it (thinking Andy Clark amongst others here). Similarly, although we know a lot about thoughts, beliefs and even relationships, we don’t know nearly as much about how thoughts and beliefs are adopted by a community, although Daniel Dennett has some thoughts about this.
So, it’s hardly surprising that when it comes to pain, we struggle to understand how biological processes, psychological processes and social ones interact to produce the experience of one person presenting for treatment at this time in this way – but this does not mean we should ignore what we DO know, which is that within each domain there is much to explore!
My preference is to draw on Brian Haig‘s idea of an Abductive Theory of Scientific Method, and in particular this paper on clinical reasoning, scientific method and abductive reasoning. The basic idea is that we recognise the existence of a phenomenon because either we’ve seen it before, or we’ve read about it. We distinguish between random events and a phenomenon because these appear to be consistent and repeated. Then we begin to generate some hypotheses to explain the presence of this phenomenon. Abduction is the process of studying what we see/observe/know (“facts”) and developing a theory to explain them (or generating a hypothesis). We then go about testing that hypothesis – and while we never truly confirm it, we can reject an alternative hypothesis tested against the first. As a result we arrive at what we can call a plausible explanation – something that “makes sense”, given what we’ve observed, and what we know about the world and how it works.
More about this geeky stuff next week. Meanwhile I think it’s worth pondering this: in “usual science” we somehow arrive at a hypothesis, and then set about testing it. No-one, it seems, knows where the original hypothesis comes from – and it’s rarely truly acknowledged. Researchers typically look for “gaps in the literature”, something that hasn’t been asked or answered yet, but what if you happen to be a clinician? I think clinicians routinely observe “interesting things” that, if we took some time to measure them, might be a phenomenon. Something that hasn’t yet been explained. I also think we have opportunities to be scientific about how we investigate what we see and do, if we’re prepared to be systematic and think about how we might control for confounds/bias. And I think those edges between levels within a hierarchy or between domains might be fruitful areas for clinicians to be exploring – bringing us to a practical application of Engel’s BPSM.
ENGEL, G. L. 1980. The clinical application of the biopsychosocial model. The American Journal of Psychiatry, 137, 535-544.
HAIG, B. D. 2008. Scientific method, abduction, and clinical reasoning. Journal of Clinical Psychology, 64, 1013-1018.