Gorgeous representation of the gorgeous Ptolemaic cosmological modelThe Rant Behind The Patient Compliance Rant
A primary precept of AlignMap has been and continues to be my contention that the contemporary concept of patient compliance is fundamentally flawed. I have made that argument numerous times, most recently in the final portion of the preceding post, Emergency Room Study Confirms Confusion About Instructions - And Compliance.1
The goal of today’s post, however, is not a defense of my position but an explanation of how it might2 be possible that the thousands of published works and clinical studies as well as the theoretical work completed in the field of treatment adherence since the popularization of the current notions of compliance and noncompliance by Sackett and Haynes in the 1970s3 could be wrong and the likely consequences if no changes are forthcoming in that model.
So, for now, I ask that the reader grant Coleridge’s “willing suspension of disbelief”4 re the validity of my own ideas about adherence in order to focus on understanding how it is possible that so many smart and experienced individuals and so many well-funded, well-staffed, and well-intended institutions could be wrong about the basics of patient compliance.
The Risk Of A Ptolemaic Model Of Treatment Adherence
Whenever I find myself disconcerted about the lack of progress in patient compliance in the past century, a period during which great advances were made in almost every other aspect of healthcare, I seek solace by putting this disappointment in context.
After all, Ptolemy proposed a model of the cosmos5 which positioned the Earth at its stationary center with the moon, sun, planets, stars, and such revolving around it.

Ptolemy
This model, called the Ptolemaic System,6 held sway for 1,500 years,7 yet it turns out to have been wrong.
The Ptolemaic System was not the dominant school of thought for 1500 years because Ptolemy or Aristotle (whose concepts about a geocentric universe were the starting point for Ptolemy) or any of the others who contributed their ideas to the effort were con men running a scan or because the intellectuals, astronomers, clerics, government officials, and scholars who bought into the model were dummies.
The problem, in fact, was that Ptolemy and the others were extraordinarily smart - so smart that they could build, rebuild, revise, jerry-rig, adapt, bend, and reorient a system that could explain away any apparent discrepancies between real world observations and the results that were expected based on the projections of the model irrespective of its correlation - or lack of correlation - with reality.
Not that reconfiguring the model to make it functional didn’t require some fancy footwork.
Making The Current Patient Compliance Model Work
What if we throw in 40 or 50 epicycles and a few deferents? And maybe an equant?
Note: The oversimplified account that follows centers the adjustments Ptolemy and others made to compensate for errors in the system rather than the Ptolemaic Model itself.8
As discrepancies between model and reality became apparent, Ptolemy et al added loops, revolutions, retrograde motions, and all manner of kinky maneuvers to hypothetical orbits of heavenly bodies to make actual events and theoretically determined calculations congruent.9
In order to explain, for example, retrograde motion, astronomers working long before Ptolemy came on the scene, theorized that the orbits of celestial bodies included epicycles, smaller circles looping around the primary pathway centered on the Earth.
Ptolemy added some refinements such as eccentrics and equants, to explain other details of heavenly observations.
Wikipedia’s description of the Ptolemaic Model is instructive:
In the Ptolemaic system of astronomy, the epicycle (literally: on the circle in Greek) was a geometric model to explain the variations in speed and direction of the apparent motion of the Moon, Sun, and planets. It was designed by Apollonius of Perga at the end of the 3rd century BC. In particular it explained the retrograde motion of the five planets known at the time. Secondarily, it also explained changes in the apparent distances of the planets from Earth.
In the Ptolemaic system, the planets are assumed to move in a small circle, called an epicycle, which in turn moves along a larger circle called a deferent. Both circles rotate counterclockwise and are roughly parallel to the Earth’s plane of orbit (ecliptic). The orbits of planets in this system are epitrochoids.
The deferent was a circle centered around a point halfway between the equant and the earth. The epicycle rotated on the deferent with uniform motion, not with respect to the center, but with respect to the off-center point called the equant. The rate at which the planet moved on the epicycle was fixed such that the angle between the center of the epicycle and the planet was the same as the angle between the earth and the sun.
The video version is even more impressive
Waiting For The Copernicus of Compliance
I am, of course, suggesting that as long as we maintain allegiance to the current models of patient compliance, successes may be limited to explaining away discrepancies between an artificial system and reality.
Consider this simple example. Over the past five years, I come across a plethora of publications arguing, with varying levels of vehemence, that one name or another be used exclusively to designate the phenomenon that most clinicians call “patient compliance.” Without denying the importance of language, patient participation in treatment planning, or any other shibboleth of choice, I find it requires minimal effort to equate the compliance vs adherence vs concordance vs whatever name game with, say, the epicycles in the Ptolemaic System.11
It’s just a thought; I could be wrong.
I guess we can wait another 1400 years or so to find out.
For Animation Addicts
- Way cool Ptolemaic System Simulator
- Scary Epicyle Demo
Footnotes
- The relevant segment comprises the paragraphs following the heading, “Is The Problem Noncompliance Or Health Illiteracy Or Both?
And Why Should Anyone Care?”↩ - I have italicized some of the indicators of the subjunctive mood to emphasize that my immediate goal is not developing a syllogistic proof that the current ideas are wrong but demonstrating how such an inaccuracy could take root and persist.↩
- See Sackett DL, Haynes RB, eds. Compliance with Therapeutic Regimens. Baltimore, MD: Johns Hopkins Univ Pr; 1976. and Haynes RB, Taylor DW, Sackett DL, eds. Compliance in Health Care. Baltimore, MD: Johns Hopkins Univ Pr; 1979.↩
- In this case, the more precisely correct phrase would be, I suppose, “willing suspension of belief [in the current model of compliance],” but quibbling with Coleridge is beyond the scope of this post.↩
- If one is seeking context, the concept of the cosmos is a handy starting place↩
- Yeah, I know - big surprise, eh?↩
- Depending on the source, this era during which the Ptolemaic System was dominant is given as 1300-1500 years↩
- In any case, the Ptolemaic Model is an amalgam of Ptolemy’s own ideas, contributions from his contemporaries, and the concepts developed by his predecessors. Starting points for Ptolemy’s system follow: Pythagoras (569-475 B.C.) articulated what became known as the Pythagorean Paradigm which held that the planets, Sun, Moon and stars move in circular orbits at an unvarying speed, and that the Earth is at the center of the motion of all celestial bodies. Aristotle (384–322 B.C.) further developed a model of the cosmos with the Earth at its center because most popular and observational evidence as well as his own theories of physics (most importantly, he hypothesized that objects by their nature move toward the center of the Earth unless acted on by an external force) necessitated a geocentric universe. His notion, adapted from yet another philosopher, was that each planet, the Sun, and the Moon moved on its own crystalline sphere arranged concentrically around the Earth. The largest sphere surrounding all of the other celestial bodies was reserved for the stars.↩
- Ptolemy’s orbital variations are, I hasten to note, no weirder than other advanced areas of science. In an article on “strange quarks,” for example, Wikipedia observes, without a trace of jest, that “the φ flavorless meson is pure strange-antistrange.” Further, there is evidence that the Ptolemy’s model is not significantly more complex than the Copernican system that replaced it.↩
- From History and Philosophy of Western Astronomy↩
- Obviously, the choice of names for compliance and the use of epicycles in the Ptolemaic System are not truly equivalent - applying the right epicycles to the Ptolemaic System actually produces the correct, real world answer. And, I have never seen any nifty animations illustrating the choice of names.↩









1 response so far ↓
1 jean lalonde // Sep 22, 2008 at 10:37 am
Your posts area great - glad you’re back.