27 Patient Compliance:

Pharmionics, a New Discipline

Jean-Michel Me ́try

27.1 Summary

Patient noncompliance with prescribed drug regi-
mens is a long recognized, butuntil recently poorly
analyzed, aspect of ambulatory healthcare. It was
only in 1987 that objective, satisfactory methods
became available for compiling drug-dosing
histories in ambulatory patients, which is the
cornerstone for measuring compliance. Since
then, much new information has been gained.
The termpharmionicsrefers to the new branch of
the biopharmaceutical studies, namely the study of
what patients do with the medicines they have been
prescribed.
It is important to have sound terminology for
pharmionic studies.Adherenceis a blanket term
that covers the three phases of ambulatory pharma-
cotherapy. The first phase isacceptance, that is,
whether or not the patient accepts the principle and
regimen of the prescribed treatment. If acceptance
is forthcoming, the patient commences to engage
with the drug-dosing regimen. The second phase is
conveniently calledexecution, the quality of which
is indicated by the parameter calledcompliance,
which is the extent to which the patient’s dosing
history corresponds to the prescribed dosing regi-
men. The third phase is calleddiscontinuation, that
is, when the treatment ceases – whether because

the prescriber called for it to cease, or because the

patient stopped engaging with the dosing regimen

and either stopped the treatment altogether or

dropped his/her drug intake to levels so low as

to be therapeutically inconsequential. It is conve-

nient to use the termpersistencefor the length of

time between the first-taken dose and the last-taken

dose in a course of ambulatory pharmacotherapy.

The reason for separating these three phases is that

the first and third phases are binary, or dichoto-

mous, phenomena, in that they either happen or

they do not. The second phase, however, is contin-

uous and capable of varying from day to day,

sometimes quite widely. One cannot have a single

parameter that describes both dichotomous and

continuous phenomena, and for that reason, the

termadherence, which has a certain convenience,

is inherently nonquantitative. Someone, for exam-

ple, can be accurately termed a ‘poor adherer’,

either because of nonacceptance, becauseof accep-

tance but poor quality of execution or because of

short persistence, with either good or poor compli-

ance during the period of time that the patient was

engaged with the drug-dosing regimen.

From a methodological point of view, the most

challenging of the three phases of ambulatory phar-

macotherapy has been execution, which is the sub-

ject of this chapter.

Principles and Practice of Pharmaceutical Medicine, 2nd Edition Edited by L. D. Edwards, A. J. Fletcher, A. W. Fox and P. D. Stonier
#2007 John Wiley & Sons, Ltd ISBN: 978-0-470-09313-9