Shared decision making should extend to diagnosis


By Tony James

8 Nov 2017

The importance of engaging patients to share decisions about diagnosis has been neglected despite a strong focus on the concept in treatment decisions, an analysis in the BMJ has claimed.

Professor Zackary Berger from Johns Hopkins University in Baltimore and colleagues said decisions about diagnostic processes and investigations posed distinct challenges.

“A key difference is the nature of the patient’s concerns,” they said. “Treatment decisions assume an existing condition, whereas diagnostic situations require clarification of the condition – for example, ‘my child fell and hit his head, does he need a brain scan?’

“This difference is critical, because uncertainty is often much greater for diagnosis than treatment, making it much more challenging to explain the options and weigh the risks and benefits to the patient.”

Managing the many diagnostic possibilities for an undifferentiated symptom is complicated by a patient’s tolerance of uncertainty, how the individual manages trade-offs between false negative and false positive results, and how they act on test results.

“Precisely quantified benefits and harms are less likely to be available for diagnosis than treatment, especially with respect to incidental or false positive results,” Professor Berger and colleagues said. “This is sometimes referred to as the ‘cascade effect’, in which initial, smaller scale decisions give rise to a chain of diagnostic procedures that might be unwarranted in hindsight.”

Decision making for diagnosis is often more iterative than for treatment, and may need to happen over an extended period of time.

They provided a series of case studies to illustrate the variety of strategies that could be needed.

For example, for routine diagnostic cases and when the uncertainty and risks of testing are low, a straightforward approach can be used to discuss the diagnosis. This might apply to an elderly man with bitemporal headaches and jaw claudication in whom a low-risk, simple ESR could contribute to the diagnosis of dangerous, but treatable giant cell arteritis.

Some diagnostic processes should be straightforward but can be complicated by patients’ individual concerns. Their example was the investigation of lower back pain following a strain in a middle aged man who wanted an MRI, and on further discussion revealed a sibling had just been diagnosed with renal cell cancer that first manifested as back pain.

In other cases patients’ needs and opinions can need extensive discussion, for example genetic testing for Huntington’s disease in the presence of a family history.

Emergency presentations can offer their own challenges, for example if time-critical alteplase for acute stroke is needed but also carries risks and the family wants a time-consuming MRI to confirm the CT scan before they accept the diagnosis.

High uncertainty and high stakes can require detailed discussion with the patient or carers, but within a very constrained timeframe.

In each case, shared decision making requires relationship building, exchange of information, and responding to patients’ and carers’ emotion, but ideally leads to patient empowerment and improved self management.

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