Authors’ reply to “Paradox or misinterpretation? Re-examining McCaffery’s maxim and the International Association for the Study of Pain definition of pain”

TO THE EDITOR

We welcome the opportunity to respond to the letter from Dr. van Rysewyk [1], with whom two of us (Drs. Cohen and Quintner) have collaborated in the past [2].

The essence of Dr. van Rysewyk’s remarks arising out of our article [3] seems to be an assertion of “McCaffery’s maxim”, namely, “Pain is whatever the person says it is and exists whenever he or she says it does” [1]. This stance refers to the validity, or epistemic status, of a self-report of pain. Dr. van Rysewyk suggests that our thesis undermines “the epistemic structure required for effective clinical communication and care” which, according to him, “reinforces the conceptual and clinical integrity of the International Association for the Study of Pain (IASP) definition.”

Our article does indeed challenge this claimed “integrity” of the IASP definition, at both conceptual and clinical levels, but not at the expense of the experiencer’s self-report [3]. To reiterate two of the main points made in that article:

① The “association” between a pain experience and “actual or potential tissue damage”, as stated in the IASP definition [4], is logically a statement of causation. That is, a pain experience implies tissue damage. (We argue that the causal association should be with nociception rather than with tissue damage, which is not defined. However, that very important distinction is not germane to this response to Dr. van Rysewyk’s letter.)

② The IASP definition of pain gives equal weight to “an experience associated with...tissue damage” and “an experience...resembling that (association).”

Given that ① (above) requires that an association with tissue damage be demonstrated, two questions then arise:

ⓐ Who determines whether there is an association with tissue damage?

ⓑ By whom and how is “resembling” that association to be determined?

Situation ⓐ describes a usual clinical encounter, when a pain experiencer presents to a pain observer (clinician). The implicit task of the latter is to find the “tissue damage” (or, as we would argue, to find evidence that nociception has been engaged), especially in cases where the experiencer has been unable to do so.

Situation ⓑ occurs when neither the pain experiencer nor the pain observer can find an association, but the experiencer maintains that such must be present, via their assertion of “pain”. This is one of the two paradoxes embedded in the IASP definition of pain. We wrote: “The experiencer maintains a belief that there must be tissue damage, while the observer can find no corroboration for that assertion. Although contradictory, both views are simultaneously valid” [3] (emphasis added here).

Thus, we show that the problem lies not in the experiencer’s report but rather in the definition of pain itself, which prescribes a connection between pain and tissue damage while simultaneously allowing that prescription to be violated.

Our article [3] does not question in any way the internal validity or the sincerity of a self-report of pain. However, we argue that it is a fundamental role of the clinician to dissect a person’s report of “being in pain” (despite the strangeness of that common English usage), in order to determine, for clinical purposes, whether that expression of distress is concordant with the definition of pain.

Our argument to resolve this paradox is that it is only the observer who can definitively determine ⓐ in the clinic. We hold that this stance is wholly consistent with the note that accompanies the IASP definition of pain, “A person’s report of an experience as pain should be respected” [4], as Dr van Rysewyk quotes. But “respecting” a report of pain is not the same as accepting it or believing it. In fact, we argue further that respect for the experiencer’s distress is not violated at all in situation ⓑ, as it is incumbent on the observer to determine a source of that distress that is not “tissue damage” (or, as we would prefer, that is not nociception). This is the polar opposite of “undermining clinical practice” [1].

Dr. van Rysewyk wrote that our “...objection that observers cannot know with certainty whether the patient is making an association between personal pain and tissue damage seems beside the point of the IASP definition...”, which, he claims, “...was intended to operate under conditions of uncertainty” [1]. However, we have shown that it is precisely this point that weakens the integrity of that definition and therefore its scientific and clinical applicability.

Dr. van Rysewyk claims that we have misinterpreted a principle rather than identifying a paradox. If that principle is unquestioningly to apply the “rule of first-person authority,” then a variety of distressing human experiences may be subsumed under the rubric of “pain.” In our view, this situation would not enhance understanding. In the interests of avoiding ambiguity and promoting certainty, definitions need to be as exact as possible and must not contain paradoxes. In contrast to Dr. van Rysewyk’s assertion that “Pain, a subjective experience, lacks an independent criterion against which first-person reports can be straightforwardly verified or falsified” [1], we argue that such a criterion does exist, namely a definition that grounds the pain experience in biology, specifically nociception. Hence, our proposal (which incidentally builds on one of our joint publications with Dr. van Rysewyk [2]) is that pain be redefined as “a mutually recognised experience contingent on nociception” [3].