WHAT IS A DECISION AID?

As the term implies, decision aids are tools that are designed to facilitate health decision making between patient and practitioner. Probably the most widely used definition of decision aids is the following, from the Cochrane Library’s systematic review:

Although there is some variation in viewpoints, there is general consensus among international groups (IPDAS 2006) developing decision aids that, in the context of making decisions about health, such tools should be:

We propose that decision aids should also be accessible to people from a range of literacy levels, but the best mechanism for achieving this is still being determined. A more detailed list of quality criteria for decision aids is discussed later in this chapter.

Interest in clinical decision making has been increasing for some time. David Eddy wrote a significant series of essays over a decade ago in which he proposed that health decisions not only include analyses of scientific and clinical evidence but also patient preferences. He maintained that most decisions involved weighing up benefit against harm and that some judgement is involved (Eddy 1996). In the past, such a weighing up process might have been completed by the clinician on behalf of the patient. However, as this chapter will demonstrate, societal attitudes have changed substantially, and patients increasingly want to be involved in these decision-making processes. Clinicians may assume wrongly that their preferences are the same as those of their patients. There is now empiric evidence that consumers and clinicians value at least some treatment outcomes differently. For example, the value patients place on stroke prevention with anticoagulants is different from that of their physicians (Protheroe et al 2000), and families are content to discontinue antiepileptic drugs at different levels of risk than are their physicians (Gordon et al 1996). The concepts proposed by Eddy have been further developed by members of the Evidence-Based Medicine Working Group and others to suggest that research evidence should be combined with clinical expertise, the patient’s clinical state and circumstances and the patient’s preferences and actions (Haynes et al 2002, Trevena & Barratt 2003). Decision aids may be one mechanism by which this can be achieved.

A systematic review of effective strategies for communicating with patients about evidence showed that patients’ understanding of evidence was improved by most structured tools but particularly if they were tailored, personalized and/or interactive. Decision aids have the capacity to achieve tailoring and also to facilitate the elicitation of patient preferences through personalized worksheets and value clarification exercises (Trevena et al 2005).

WHAT IS THE EFFECT OF DECISION AIDS ON PATIENT INVOLVEMENT?

A Cochrane systematic review of 32 decision aids concluded that decision aids increased patient knowledge of the options compared to usual care, with gains in such knowledge ranging from 9 to 30 percentage points (weighted mean difference (WMD) 19 points, 95% CI: 13 to 24). Studies also suggested that decision aids increased realistic expectations about the benefits and harms of different healthcare options as measured by patients’ perception of the probability of outcomes. The review indicated improved patient satisfaction with the decision-making process and greater agreement between patient values and actual choice.

There is some evidence that decision aids increase the proportion of patients who are actively involved in decision making. The Cochrane systematic review included seven randomized controlled trials comparing decision aids against usual care. These trials covered a range of decisions such as prostate cancer screening, treatment of early prostate cancer, treatment of ischaemic heart disease, anticoagulation in atrial fibrillation, colorectal cancer screening and the use of hormone therapy during the menopause. The meta-analysis showed that people receiving a decision aid were 30% less likely to report having a passive (practitioner-controlled) role in their decision (RR 0.7; 95% CI: 0.5 to 0.9). The corollary of this is that decision aids were more likely to be associated with an active role in decision-making (RR 1.4, 95% CI: 1.0 to 2.3). The quality of the decision process was also significantly improved. In particular, uncertainty about decision making (decisional conflict) was significantly reduced (WMD −9.1 of 100, 95% CI: −12 to −6).

HOW CAN WE ASSESS PATIENT INVOLVEMENT?

The measurement of patient involvement in decision making has mainly used the Control Preferences Scale (Degner et al 1997). Patients usually assess their actual or preferred role from the five options shown in Box 34.1.

Although this scale continues to be widely used in many studies to measure patient involvement, some researchers have questioned its validity (Davey et al 2004; Entwistle et al 2001, 2004). A systematic review of instruments to measure patient involvement came to a similar conclusion, suggesting that patient involvement is a complex construct that requires more qualitative assessment (Elwyn et al 2001). As a result of this, other instruments have now been used and validated in analysing recorded consultations (Elwyn et al 2005, Shields et al 2005). Both of these instruments expand the Control Preferences Scale to assess whether patients were provided with a range of options, their pros and cons, whether the patient’s preferred level of involvement was assessed, whether questions were invited and clarification offered. The effect of decision aids on patient involvement as measured by these new instruments has not yet been published.

TO WHAT EXTENT DO PATIENTS WANT TO BE INVOLVED IN HEALTH DECISIONS?

There is increasing evidence that a high proportion of people want to be actively involved in a range of health decisions. A telephone survey of 8119 randomly selected adults from eight European countries showed some inter-country variability in the proportion of people wanting to be actively involved in healthcare decisions but overall, the majority preferring such a role. This was particularly so in people under the age of 35 years, of whom 74% indicated a preference for active involvement in treatment decisions (Coulter & Jenkinson 2005). Desire for greater participation in decision making was increased in people with higher socioeconomic status but there was still a substantial proportion of people wanting participation even in the lowest socioeconomic groups (McKinstry 2000). Similarly an Australian survey of 652 women showed that 94.6% preferred to share decisions about diagnostic tests and 91.2% to share treatment decisions (Davey et al 2002). The Australian study, however, showed no difference across age groups.

A closer look shows that what ‘preference for involvement’ actually means to patients can vary not only with culture and age, but also with the decision itself. Cancer patients in one study indicated that involvement for them meant having information but not necessarily making the decision about treatment. They perceived more opportunity for participation in decisions about adjuvant therapy than about definitive surgical management. They also considered that decisions about physical therapies such as stoma care and psychological therapies such as counselling were more amenable to active roles in decision making (Beaver et al 2005). Cancer patients also appear to have different levels of preferred involvement with respect to information needs about prognosis (Leydon et al 2000).

Despite a preference for active involvement, it seems that many patients continue to value the doctor’s opinion in some circumstances. A study of 202 patients attending a general medicine clinic reported that 62.5% preferred shared, 22.5% physician-based and 15.5% patient-based decision making. More than half of respondents rated the doctor’s opinion as the most important information for decision making. These patients were considering decisions about invasive medical procedures such as endoscopy, biopsy, interventional radiology and cardiac catheterization (Mazur et al 2005).

Studies of screening decisions appear to show a higher level of patient preference for involvement. A study of women aged 40–49 considering screening mammography showed that 46% preferred shared and a further 46% preferred patient-based decision making compared with 9% preferring physician-based decision making (Nekhlyudov et al 2005).