Are patient decision aids effective? Insight from revisiting the debate between correspondence and coherence theories of judgment

Judgment and Decision Making, Vol. 4, No. 2, March 2009, pp. 141–146
Are patient decision aids effective? Insight from revisiting the
debate between correspondence and coherence theories of judgment
Victoria A. Shaffer? and Lukas Hulsey
Department of Psychology
Wichita State University
Abstract
Research endeavors to determine the effectiveness of patient decision aids (PtDAs) have yielded mixed results. The
con?icting evaluations are largely due to the different metrics used to assess the validity of judgments made using Pt-
DAs. The different approaches can be characterized by Hammond’s (1996) two frameworks for evaluating judgments:
correspondence and coherence. This paper reviews the literature on the effectiveness of PtDAs and recasts this argument
as a renewed debate between these two meta-theories of judgment. Evaluation by correspondence criteria involves mea-
suring the impact of patient decision aids on metrics for which there are objective, external, and empirically justi?able
values. Evaluation on coherence criteria involves assessing the degree to which decisions follow the logical implica-
tions of internal, possibly subjective, value systems/preferences. Coherence can exist absent of correspondence and vice
versa. Therefore, many of the seemingly con?icting results regarding the effectiveness of PtDAs can be reconciled by
considering that the two meta-theories contribute unique perspectives. We argue that one approach cannot substitute for
the other, and researchers should not deny the value of either approach. Furthermore, we suggest that future research
evaluating PtDAs include both correspondence and coherence criteria.
Keywords: correspondence, coherence, patient decision aids, medical decision making.
1 Introduction
2 Application to patient decision
aids
In 1996, Kenneth Hammond argued that the ?eld of judg-
ment and decision making has taken two distinct paths,
describing those two paths as meta-theories used in the
Hammond’s meta-theories have been applied to social
evaluation of judgments. In the correspondence meta-
policy in many domains including medicine. There are
theory, judgments are compared to objective facts with
many applications within the medical ?eld; however, this
article pertains speci?cally to treatment choices made by
the explicit goal of evaluating the empirical accuracy of
patients. For many treatment decisions, there is a domi-
the judgments. In contrast, the coherence meta-theory
nant treatment choice, or a single “best” therapeutic ac-
assesses the logical consistency of judgments. In this
tion. This choice is easy because the treatment has a clear
framework, judgments are evaluated by the degree to
advantage — effectiveness is high and/or side effects are
which they are similar to solutions given by logical, math-
low. These treatment choices do not necessitate much as-
ematical, or statistical theories. Judgments are not com-
sistance. However, there exist a number of medical con-
pared to an external “true” value; instead judgments are
ditions for which no single treatment choice dominates.
compared to a normative rule, often mathematical in na-
These are the cases in which the patient must make trade-
ture. While correspondence focuses on the accuracy of
offs between different dimensions or features of treatment
judgments, coherence focuses on the rationality of judg-
options. For example, risk and potential bene?t are of-
ments.
ten positively correlated, and a choice must depend upon
how an individual values the potential bene?ts and harms.
Currently there is no best therapeutic course of action for
?Address:
Victoria A. Shaffer,
Wichita State University,
1845 Fairmount St., Wichita, KS 67260–0034.
Email:
victo-
menopause, and women are commonly asked to choose
ria.shaffer@wichita.edu.
whether or not to begin hormone replacement therapy
141

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Judgment and Decision Making, Vol. 4, No. 2, March 2009
Evaluating patient decision aids
142
(HRT). In addition to alleviating some of the symptoms of
3 The debate about the effective-
menopause (weight gain, hot ?ashes, poor memory, etc.),
ness of patient decision aids
HRT also helps to protect the body from osteoporosis.
However, HRT is also associated with an increased risk of
breast cancer, heart disease and stroke. Therefore, each
The Cochrane Collaboration Patient Decision Review
individual patient must weigh the increased health risks
Group (2003) summarized the results of 35 randomized
against the bene?ts, protection from osteoporosis and re-
controlled trials that evaluated the effectiveness of PtDAs
duction in symptoms. Other similar examples include
in comparison with control groups receiving the usual
treatment for menorrhagia, ischaemic heart disease, atrial
care or simpler decision aids. Following the Cochrane
?brillation, abnormal uterine bleeding, prostate cancer,
Review, the IPDAS symposium was created to debate
and breast cancer.
whether or not patient decision aids are the best way to
These types of treatment choices are very dif?cult for
improve clinical decision making. A vote after the sym-
patients and their physicians cannot guide them to the
posium revealed that medical professionals are divided
“right” answer. Therefore, a class of decision aids has
in their opinion of the effectiveness of PtDAs with about
been developed to help patients make dif?cult treatment
half believing PtDAs to be effective in improving clini-
choices between two or more options. Patient decision
cal decision making thus favoring their widespread im-
aids (PtDAs) are designed to educate patients on the vari-
plementation and half believing PtDAs do not improve
ous treatment choices and their associated risks and ben-
clinical decision making thus opposing their implemen-
e?ts, help patients understand the values they place on
tation (Holmes-Rovner et al., 2007). Although a num-
those risks and bene?ts, and improve communication be-
ber of other issues were addressed, a major portion of
tween patients and doctors. The emphasis on improving
the debate focused on the criteria for evaluating the suc-
patient decision making evolved during the shift in pa-
cess of PtDAs. Wendy Nelson, of the HHS National Can-
tient care philosophy from informed consent to informed
cer Institute, described the current mixed bag approach
choice or shared decision making. PtDAs were heralded
to evaluating PtDAs: “What is a quality decision, and
as a way to improve informed choice, reduce geographic
what constitutes quality decision making? Because we
differences in treatment choices, combat the rise of con-
lack an agreed-upon de?nition of quality, proponents of
sumerism in medicine, and increase patient satisfaction
decision aids have operationalized quality in a wide vari-
with the treatment process (O’Conner et al., 2003).
ety of ways” (Holmes-Rovner et al., 2007, p. 602).
The number of PtDAs steadily increases each year, and
Researchers evaluating PtDAs determine the effective-
the medical community has recently begun to evaluate the
ness of a given decision aid by assessing whether or not
effectiveness of these programs. In 2003, the Cochrane
it improves patient decision making. There have been
Collaboration Patient Decision Aid Review Group pub-
two distinct approaches to operationalizing improved de-
lished an extensive evaluation of the effectiveness of Pt-
cision making, one that roughly captures the coherence
DAs. In 2006, the Society for Medical Decision Mak-
approach and one that more closely approximates the
ing held the International Patient Decision Aids Stan-
correspondence approach. Researchers adopting the co-
dards (IPDAS) symposium, which was designed to de-
herence approach often ask whether the use of PtDAs
bate whether PtDAs were the best way to improve patient
improves the congruence between patients’ stated val-
decision making. Subsequently, the journal Medical De-
ues and their treatment choices (O’Connor et al., 2007;
cision Making dedicated an entire issue to the future of
O’Connor et al., 2003). In contrast, researchers adopt-
shared decision making in 2007, which contained a fo-
ing the correspondence approach typically ask whether
cus on evaluating the effectiveness of PtDAs (Helfand,
the use of PtDAs results in increased quality of life (Mc-
Barnato, & Holmes-Rovner, 2007). What has emerged
Caffery, Irwig, & Bossuyt, 2007). These two methods
is a set of con?icting opinions about the value of PtDAs
frequently lead to different conclusions about the effec-
and, more basically, about the criteria upon which PtDAs
tiveness of PtDAs. We argue that the two sides in the
should be evaluated. Reviewing this debate shows that its
PtDA controversy represent a renewed debate about cor-
arguments parallel those between the correspondence and
respondence versus coherence criteria. The following
coherence theorists of decision making. Hence, the goal
sections will discuss how the correspondence and coher-
of this paper is to re-cast this discussion in light of these
ence theories have been applied to the area of PtDAs and
two meta-theories in the hope of learning lessons from a
the bene?ts and dif?culties associated with adopting each
previous incarnation of this debate.
approach.

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Judgment and Decision Making, Vol. 4, No. 2, March 2009
Evaluating patient decision aids
143
4 The correspondence approach to fore, if these were the only measures adopted, it may be
evaluating patient decision aids
dif?cult to conduct timely research. In addition, some re-
searchers have adopted the position that decision-making
Hammond’s 1955 article, “Probabilistic functioning and
should be evaluated before the outcome of the decision
the clinical method,” marked the beginning of the corre-
is known. In support of this position, Baron and Her-
spondence approach to decision making. Although for-
shey (1988) documented the outcome bias in evaluating
mally articulated by Hammond in the 1950s, the corre-
decisions; participants rated the quality of the decision
spondence metatheory was inspired by Egon Brunswik’s
and the competence of the decision maker more favorably
general theory of cognition under uncertainty. The cor-
after a positive outcome than a negative outcome. Fur-
respondence approach focuses on aligning human judg-
thermore, Caplan and colleagues (1991) found a negative
ment with empirical accuracy. Typically, correspondence
relationship between outcome severity and judgments of
theorists have evaluated decision making by comparing
the appropriateness of care by anesthesiologists.
human judgment to an external gold standard — often
objective facts (Hammond, 1996).
5 The coherence approach to evalu-
In the context of patient decision making, the logical
application of the correspondence approach would be to
ating patient decision aids
examine whether patient treatment choices corresponded
to the best treatment choices. However, PtDAs have been
Due to the lack of a clear gold standard and the dif?-
developed for treatment choices for which there exists no
culties associated with implementing the correspondence
single best therapeutic action. Therefore, this obvious
approach, a number of researchers have opted to evalu-
correspondence criterion is eliminated. Instead, “corre-
ate the ef?cacy of treatment decisions by using coherence
spondence” theorists evaluating PtDAs argue for the im-
criteria in lieu of correspondence criteria. This approach
plementation of other gold standards such as survival,
to the study of decision making developed in parallel to
function and well-being. More “accurate” choices lead to
Hammond’s correspondence approach. Ward Edwards is
a greater chance of survival, greater post-treatment func-
largely credited with beginning this movement in 1954
tion and improved quality of life. Health outcomes have
with his article on “The theory of decision making.” Ed-
been evaluated using general health measures such as the
wards’ research examined the rationality of human judg-
12-item Short-form Health Survey or measures that as-
ment under uncertainty using probability theory as the
sess condition-speci?c health outcomes (O’Connor et al.,
cornerstone of rationality. Edwards evaluated judgmen-
2003). However, very few studies have used these mea-
tal ability by comparing human judgment to mathemat-
sures. Out of the 35 randomized controlled trials of Pt-
ical models — as opposed to empirical accuracy. Ed-
DAs reported in the Cochrane Review, only seven studies
wards focused on a speci?c type of probability calcu-
measured general or condition speci?c health outcomes.
lus — Bayes’ Theorem. Later coherence theorists also
Five of these seven studies found no signi?cant differ-
adopted Expected Utility Theory (EUT) and its variants
ences in health outcomes for patients who used decision
and their axioms as additional yardsticks for rationality.
aids. Furthermore, these metrics appear to have been sub-
Most research on PtDAs comes from the coherence ap-
sequently abandoned. The IPDAS symposium, designed
proach. Because there is no objective gold standard or
to evaluate the effectiveness of PtDAs, de?ned a good
single best treatment, most research examining the ef-
patient decision as “one that is informed and consistent
fectiveness of PtDA asks whether the aid helps the pa-
with the patient’s values” (Holmes-Rovner et al., 2007,
tient to make a coherent choice (O’Connor et al., 2007;
p. 603). This de?nition is generally inconsistent with
O’Connor et al., 2003). In fact, two explicit goals of
the correspondence approach, and, therefore, the major-
many PtDAs are to help patients clarify their values for
ity of recent research on PtDAs has not included corre-
various health states and make treatment choices that are
spondence criteria. In fact, a recent meta-analysis of the
congruent with those values. For example, a patient who
effectiveness of PtDAs did not include any these outcome
values treatment effectiveness should be more likely to
measures, abandoning the correspondence approach in
choose a treatment with a greater success rate. How-
favor of coherence (O’Connor et al., 2007).
ever, if she values quick recovery times or pain minimiza-
There are dif?culties associated with the correspon-
tion, then she should be more likely to choose treatments
dence approach that may have led some researchers to fa-
that match this. Many PtDAs include values clari?ca-
vor a coherence approach to evaluating PtDAs. First, the
tion exercises to help patients articulate their preferences;
correspondence measures are dif?cult to evaluate in the
30 out of 51 PtDAs included in a recent meta-analysis
short term. Metrics such as survival and long-term health
incorporated some explicit values clari?cation exercise
outcomes require many years of follow-up data to be col-
(O’Connor et al., 2007). These exercises can include
lected after the initial randomized controlled trial. There-
rating different possible health outcomes, forced choice

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Judgment and Decision Making, Vol. 4, No. 2, March 2009
Evaluating patient decision aids
144
tasks where patients choose between options with a sin-
creased stress, to watchful waiting, and the cancer will
gle difference, and time tradeoff tasks where the patient
not metastasize in the majority of cases — although this
is asked to decide how many years of perfect health they
number is smaller than with a prostatectomy. There-
would trade in exchange for a certain number of years
fore, the patient’s choice would be based on his util-
in some less desirable health state. The goal of these
ities for the potential health states. Which would be
exercises is to determine how an individual patient val-
more dif?cult to live with: a small increase in the like-
ues the relative risks and bene?ts associated with the dif-
lihood that the cancer would metastasize or the risk of
ferent potential outcomes. Therefore, the coherence ap-
impotence/incontinence? In order to make the decision,
proach to determining the ef?cacy of a PtDA is to ex-
the patient has to be able to successfully predict how
amine whether treatment choices made by patients using
he would feel in these previously unexperienced health
PtDAs are congruent with their stated values (Holmes-
states. Much research has shown that people are unable
Rovner et al., 1999; Lerman et al., 1997; O’Connor et al.,
to predict their future feelings (Damschroder, Zikmund-
1999)
Fisher, & Ubel, 2005; Gilbert, Pinel, Wilson, Blumberg,
Like the correspondence framework, researchers have
& Wheatley, 1998; Riis et al., 2005; Ubel, Loewenstein,
argued that the coherence approach to evaluating patient
& Jepson, 2005a; Ubel, Loewenstein, Schwarz, & Smith,
judgments has some weaknesses. Speci?cally, evaluating
2005b; Wilson & Gilbert, 2005). Wilson and Gilbert
the rationality of a treatment decision by its congruence to
(2005) argued that people are unsuccessful at “affective
elicited preferences for health states relies on the validity
forecasting” because they mispredict their emotional re-
of the system used to elicit those preferences. There are
actions to future events. In particular, people fail to an-
some reasons to question the validity of values clari?ca-
ticipate how readily they will adapt to emotionally dif?-
tion exercises commonly built into PtDAs (Nelson, Han,
cult situations. This phenomenon has been demonstrated
Fagerlin, Stefanek, & Ubel, 2007). These exercises as-
with affective predictions for various health states as well
sume that preferences for health states are stable and that
(e.g., Brickman, Coates, & Janoff-Bulman, 1978; Ubel
patients are accurately able to predict preferences for fu-
et al., 2005b). For example, Sackett and Torrance (1978)
ture health states. However, research suggests that these
found that patients with chronic health conditions, such
assumptions could be questioned.
as dialysis, have a greater quality of life than is predicted
The coherence criterion of value congruence relies on
by people without a chronic illness. Therefore, the basic
the assumption that patients have measurable and stable
premise upon which values clari?cation exercises are de-
preferences for health states and treatment choices. This
signed — namely that patients can predict their utilities
assumption has been hotly contested by decision making
for future health states — is called into question.
researchers since the 1970s. A large body of research has
The variables we have summarized in the preceding
demonstrated that preferences appear to be constructed
sections do not represent an exhaustive list of the mea-
at the time of judgment and are sensitive to the mode of
sures used to evaluate PtDAs. There are additional vari-
elicitation and to framing effects (Slovic, 1995; Slovic &
ables that cannot be easily classi?ed as ?tting into either
Lichtenstein, 1983; Tversky & Kahneman, 1981). There-
approach or that represent a hybrid of the two approaches.
fore, in the context of a PtDAs, preferences for health
For example, researchers have examined a number of
states may be subject to framing effects, and values clar-
psychological measures such as anxiety, depression, re-
i?cation exercises may help to determine preferences —
gret, and decisional con?ict. Some take a reduction in
not discover them. This again calls into question the use
these psychological variables as evidence for the effec-
of value congruence as a yardstick for rationality.
tiveness of PtDAs (O’Connor et al., 2003; O’Connor et
Additionally, the validity of the values that patients as-
al., 2007). Similarly, some researchers argue that other
sign to health states is also questionable. Even if we as-
non-psychological measures such as persistence with a
sume that patient preferences for health states are mea-
chosen treatment choice, increased participation in deci-
surable and stable, values clari?cation exercises rely on
sion making, and reduced indecision after PtDA provide
the assumption that patients are accurately able to pre-
evidence that PtDAs are effective tools. Finally, some re-
dict their utility for future health states. For example,
searchers examine whether the use of PtDAs improves the
imagine a man diagnosed with localized prostate can-
accuracy of risk perception, which is often determined by
cer needs to choose between two approaches to dealing
normative solutions such as Bayes’ Theorem.
with the disease: watchful waiting or prostatectomy. In
Although some measures do not ?t neatly into the cor-
a very small proportion of men, a prostatectomy may be
respondence/coherence distinction, we ?nd it a useful
effective in preventing a metastasis of the cancer. How-
classi?cation tool for PtDA evaluation metrics. Corre-
ever, the side effects of prostatectomy, impotence and in-
spondence measures speak to the empirical accuracy of
continence, occur in a large proportion of men. In con-
judgments, while coherence measures speak to the logi-
trast, there are no side effects, other than perhaps in-
cal consistency of judgments. Measures from these two

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Judgment and Decision Making, Vol. 4, No. 2, March 2009
Evaluating patient decision aids
145
categories directly evaluate the quality of patient judg-
proaches improving in the next several years. In fact, the
ments. Variables outside this classi?cation system would
?eld appears to be increasingly dominated by the coher-
at best be considered indicators of good judgment.
ence approach. The recent IPDAS symposium on this
issue advocated for evaluating the effectiveness of PtDAs
from the coherence approach, with little regard for the
6 Conclusions: Suggestions for fu- correspondence approach (Holmes-Rovner et al., 2007).
ture PtDA evaluation
It was argued that PtDAs should be evaluated by whether
or not they lead patients to a good decision, with the
PtDAs have been evaluated from both a coherence and
hallmark of a good decision being one that is consistent
correspondence perspective, and the two approaches have
with a patient’s values. We do not believe that coherence
yielded con?icting conclusions. Research from the co-
approaches should be abandoned; instead, we call for a
herence approach has concluded that PtDAs help pa-
commensurate increase in correspondence research. We
tients to make more coherent decisions, i.e., the deci-
recommend that all randomized controlled trials evaluat-
sions reached after consulting these aids are generally
ing patient decision aids include both coherence and cor-
more consistent with patients’ values (O’Connor et al.,
respondence criteria.
2007; O’Connor et al., 2003). In contrast, research from
the correspondence approach has been less positive. Al-
though PtDAs have been shown to improve risk percep-
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