PDOC: giving a prognosis
Published: March 4, 2025
Last updated: March 4, 2025
Patients with a prolonged disorder of consciousness (PDOC) present clinicians with many challenges, and I will eventually discuss some. This post considers the difficulties associated with giving a prognosis. There are many, including a general lack of extensive valuable data and the problems non-expert clinical services face in accessing expert support. I have already considered the organisation of services specialised in assessing and managing this relatively rare group of patients. This post considers the available information, what aspects of the future should be considered, and how to present the prognosis. Most teams managing a patient are in a challenging position. They have little or no experience, no service is responsible for supporting them, families expect them to provide a prognosis, and, if the patient is in an acute setting, managers expect a rapid discharge. An accurate prognosis is essential when making critical decisions, yet the team does not have that information and makes poor decisions. This post stresses the importance of a network of services, especially an expert PDOC outreach service.
Table of Contents
Introduction
Rehabilitation is always complicated, and uncertainty is built into it. However, the uncertainty can be shared with the patient and discussed with team members and colleagues. This reduces personal challenge and leads to better decisions. Unconscious patients cannot be involved in any discussion, and few people have accumulated much experience, so the opportunity to discuss matters with knowledgeable colleagues is also limited.
The decisions are often substantial, determining where someone will be cared for, whether treatments continue, or whether they are admitted to hospital. The questions asked by families are typically incisive, asking questions that clinical colleagues avoid.
The main issues covered in this post are shown in the MindMap below.
PDOC - general prognosis
Professionals are always asked about the future: Will he recover? When will he walk again? How much better will she get?
Giving a PDOC prognosis for people left unconscious for more than four weeks is hampered by limited data, but most people do not use the available data. For example, the life expectancy website has a lot of information, including papers about people in a permanent vegetative state or minimally conscious state; this article tabulates actuarial life expectancy.
Section 1.7 of the 2020 National Clinical Guideline summarises the available information. As a rule, recovery of consciousness rarely occurs:
- After 3 months for hypoxic or hypoglycaemic brain damage
- After 6 months for stroke
- After 12 months for traumatic brain injury
A second helpful rule is that, after sudden-onset brain damage, the likelihood of recovery declines exponentially over time. So, the rate of change up to the present will indicate the likely future rate. There is limited research into this, but if there has been no significant change in the number of behaviours on the Wessex Head Injury Matrix or in the Coma Recovery Score – Revised total score over eight weeks, the probability of further change is low. The main caution is to check that no other factor has prevented or impeded change.
Giving a prognosis: why?
Why should we give a prognosis? Clinicians have natural fears:
- causing relatives distress and removing their hope
- being wrong, with time showing the given prognosis to be inaccurate
- making predictions in the absence of strong evidence to support them.
One crucial role in all professional practice is considering the likely consequences of potential actions. For example, a lawyer might advise that suing for professional negligence has a low (or high) chance of success and will cost a lot. In healthcare practice, one crucial part of selecting appropriate actions is understanding the consequences of acting or not acting. This crucially depends on making a prognosis.
Therefore, all professionals must make a prognosis; without doing so, they cannot make rational or justifiable decisions. We all inevitably have a view of the future, and the professional should make it explicit and public.
Additionally, relatives and other clinicians want a prognosis and often feel less stressed knowing the likely outcome even if it is not what they want. It is unreasonable not to give a prognosis.
Finally, we tend to think of prognosis as predicting an outcome, but it is also essential to consider the journey: What may happen between now and the chosen future time point?
Giving a prognosis: uncertainty.
I have already emphasised the variability seen in patients with a prolonged disorder of consciousness. Therefore, one must start by stressing that the person’s state will fluctuate, with good and bad days and that intervening infections or other events will usually worsen matters. Conversely, occasional brief higher-level behaviours may occur.
The person will also continue to change, and families must be prepared for this. Typically, the clinical state deteriorates as people age, and slower changes occur in the nervous system; for example, increasing spasticity is common. However, other changes are neutral and often challenging to explain. More spontaneous but purposeless movements may occur, or existing movements may reduce.
Although there is uncertainty, the crucial first step is understanding that uncertainty is not absolute. The professional will know that some outcomes are impossible, others are quite probable, and in the end, everyone dies. In other words, the professional must express all prognoses giving estimated probabilities.
Further, it is vital to express probabilities using numbers, not words. Words can be interpreted very differently, sometimes with dangerous consequences. (see The Art of Uncertainty. by David Spiegelhalter for a vivid explanation of why.)
It is best to give an estimated ‘best plausible outcome’ of, say 1%-5% likelihood and an estimated middle probability, and an estimated lower bound which, in these cases, must include an estimate of actuarial life expectancy. The lower outcome is best phrased as, “She might die, but if she survives, then in two years the worst outcome will be … ”.
While probability can be expressed numerically, many other concepts and words are ambiguous and add uncertainty. Therfore, it is essential to use words thoughtfully. For example, the word “recovery” is very ambiguous, as Yael Friedman exposed in her paper “On recovery: re-directing the concept by differentiating its meaning.” I have also discussed the use of recovery. As will be discussed later, specific terms must be used wherever possible.
PDOC: giving a prognosis for the journey.
What aspects of the future should we consider? It is best to evaluate the situation two years after onset for people with a prolonged disorder of consciousness because significant further change is rare. A more general prognosis may be used when the person is already two years after onset, but framing it at a particular time helps in presentation.
After highlighting this natural process, one can discuss the journey; what might the person experience over the next few months or years?
The patient may expect certain time-limited events, such as chest infections, seizures, or skin breakdown. The cumulative risk over a year may be substantial in a few people and should be mentioned.
All patients will receive care to maintain their health and well-being, sometimes called the burden of care. This concept encompasses:
- Standard nursing procedures when patients are moved or have muscles stretched. The evidence suggests these processes are associated with pain.
- Care procedures associated with tracheostomies, gastrostomies, and urethral catheters. Tracheal suction is especially likely to be unpleasant.
- Mouth care and washing of the face.
- Discomfort associated with immobility.
- Pain from any injections, and other invasive treatments.
- Loss of dignity, privacy, and autonomy. This may not be experienced, but many patients have expressed horror of public care and care from strangers before entering a prolonged disorder of consciousness.
PDOC: giving a prognosis for outcome.
After setting the outcome in the context of natural variability, change, events, and the burden of care, one can move on to the outcome.
Thus, as well as numerical probability estimates, one should use concrete terms describing an outcome; one should refer to change, not recovery or improvement. For the patient, a helpful framework is to consider:
- Autonomy.
In this context, autonomy refers to a person’s ability to control aspects of their life, for example, choosing who gives care and when. - Function.
This refers to activities and goal-directed behaviours. It can also include active participation, such as when dressing or washing. - Communication.
This refers to using language to communicate specific information or wishes, whether by speaking or using technology. The person can inform someone they have pain or want a different radio program. - Social interaction.
This refers to the ability to interact nonverbally. It includes the ability to discriminate between people and to respond appropriately, such as smiling at someone and reacting to their arrival or departure. - Accommodation.
This refers to their care setting, usually institutional care, but it also includes social contact with family, friends, and other residents in the accommodation.
The third aspect to consider is a patient’s feelings or experience. These cannot be known directly, but it seems probable that nociceptive stimulation (i.e., stimulation of harm detection neurones) activates the remaining nociceptive network, producing both pain behaviours and an associated aversive or unpleasant feeling. The only way this can be assessed is through monitoring pain behaviours when undertaking procedures that might generate pain.
The person might also feel pleasure, though the absence of specific pleasure-generating receptors may make this less likely. Nonetheless, just as one must minimise stimuli that might lead to pain and unpleasant feelings, one should also maximise stimuli that might lead to pleasure. For instance, playing familiar music a person previously enjoyed would be better than playing music they disliked.
Last, one must be hard-headed about the care and social stimulation a person will receive if moved into a different environment for long-term care. Nursing homes cannot offer the amount of personal attention by enthusiastic staff sometimes available in rehabilitation settings.
For example, a patient in a well-staffed hospice with attentive volunteers, such as a hospice or slow-stream rehabilitation setting, might occasionally interact and show pleasure. However, once moved to the cheapest long-term care environment available, they will receive much less additional attention and are likely to be isolated in their room for most of each day. Their physical care will undoubtedly be maintained, but their pleasure and interaction will be lost, and their quality of life will be affected.
PDOC: giving prognostic information.
Giving a prognosis on someone with a prolonged disorder of consciousness is always an exercise in breaking bad news. It might be better considered confirming bad news because, after someone has been unconscious for four weeks, most families will have realised that the person will not return to their previous state.
Research suggests that ‘telling the truth’ helps people when discussing prognosis in palliative care. The phrase has two meanings. It could mean informing someone of an absolute, inevitable outcome, telling them a definitive truth. This is rarely possible in healthcare. The alternative is ‘telling-in-truth’, being honest and explaining the future and its uncertainty. Acknowledging uncertainty is vital but must be a realistic and sincere appreciation. Saying, “but of course, we cannot be certain that they won’t do well” is dishonest if the speaker knows that is implausible; it is just a way of avoiding the truth.
Research also suggests that people will disclose the truth when they have a good therapeutic relationship, can read non-verbal cues, can personally acknowledge the likely outcomes, explain matters using simple and incremental steps, are in a private supporting environment, and are compassionate in their manner. The unstated pre-requisite is that the person has confidence their information is correct.
Unfortunately, because few clinicians and clinical services have seen anyone in this state before, they are naturally inexperienced, anxious about the topic, afraid of the family’s reactions to their prognosis and uncertain about how the conversation will go. With reasonable justification, they will feel that giving a prognosis is “not my job”. Nevertheless, they will probably realise that the patient will have long-term problems.
Clinicians in this position usually avoid describing their estimates of the likely outcome. Instead, they temporise or use platitudes such as “you never know; miracles do happen” or, worse, “some people do recover very well,” which, unfortunately, families interpret as true. This approach is harmful, and should be avoided.
This analysis leads to a firm conclusion. Someone with the best available information about the prognosis and the associated degree of uncertainty must give the prognosis. This person should also tell the family, though it would be appropriate for a clinician with a good relationship with the family to participate. The clinician might lead the discussion, but the expert should be present to handle inevitable questions.
The inevitable second conclusion is that an expert service must be available to the patient and responsible clinical team; I have already discussed this.
Conclusion
This post has not given information and a procedure for inexperienced and non-expert clinicians and services, because expecting them to provide a prognosis is unfair and unrealistic. The consequences following on from a prognosis are significant and require expertise and care. However, patients expect clinicians to give a prognosis and decisions must be made. Prognostic information provided by people with inadequate information will often cause irreparable harm to family members who develop unrealistic expectations. The decisions made will use beliefs about the future that are usually incorrect, which risks damage to the patient. Alternatively, decisions are not made, and the person is transferred to long-term care where they are forgotten, risking harm to the healthcare system. The need for an expert outreach service is compelling.
