By Dr Tom Bendinger, Consultant in Pain Medicine and Pain Medicine Expert Witness.
Prognosis is one of the most important, and most difficult, aspects of a medico-legal pain assessment. Courts and solicitors understandably want clarity, but chronic pain rarely permits the precision a seemingly confident opinion implies. This article sets out what a pain expert can and cannot reasonably say about the future course of a claimant’s condition.
Introduction
Courts, solicitors and claimants understandably seek clarity on prognosis. They may ask whether pain will resolve, whether symptoms will remain lifelong, whether the claimant will return to work, what treatment is required and whether future deterioration is expected. The temptation for an expert is therefore to provide a seemingly precise answer: symptoms will resolve within 12 months, improve within two years, or remain permanent.
Chronic pain rarely permits that degree of precision.
Once pain has persisted beyond normal tissue healing and has become embedded within a complex interaction of biological, psychological and social factors, the future course becomes inherently probabilistic. The clinical literature identifies numerous prognostic factors, but their predictive ability at the level of an individual patient is limited. Even apparently important factors such as pain severity, psychological distress, catastrophising, sleep disturbance or previous pain modify probability rather than determine outcome. Prognostic research in this area is consistently marked by heterogeneity between studies and substantial uncertainty around individual prediction.
The task of the medico-legal pain expert is therefore not to predict the future with certainty. It is to provide a reasoned estimate of the most probable clinical trajectory, to identify factors capable of improving or worsening that trajectory, and to explain the limits of available evidence.
The central question should consequently be: what aspects of prognosis can reasonably be stated on the balance of probabilities, and what aspects should remain explicitly uncertain?
Chronic pain is not simply acute pain lasting longer
A fundamental prognostic distinction must be made between acute injury and established chronic pain.
For many acute musculoskeletal injuries, tissue healing provides a reasonably predictable framework. Soft-tissue injuries heal, fractures unite and surgical wounds recover within broadly understood biological timescales. The persistence of pain beyond those timescales does not necessarily indicate continuing tissue injury.
Chronic pain is biologically and behaviourally different from acute nociceptive pain. Persistent pain may involve altered sensory processing, psychological distress, disturbed sleep, avoidance of activity, reduced physical conditioning, social factors and changes in the individual’s relationship with pain.
Consequently, once a claimant has experienced persistent pain for several years, it may no longer be realistic to forecast complete symptom resolution simply by extrapolating from the natural history of the original injury. The longer symptoms persist, particularly where they have become widespread or associated with substantial functional, psychological and social consequences, the less confidently an expert can identify a specific date for recovery.
This does not, however, mean that chronic pain is inevitably permanent. Long-term studies demonstrate that symptoms and disability may improve substantially even after prolonged pain. What is generally much less predictable is which individual patient will improve, by how much, and over what period. Long-term follow-up of chronic pain populations demonstrates that meaningful changes in functioning can occur years after initial rehabilitation, illustrating why chronicity should not automatically be equated with irreversibility.
Prognosis should be divided into pain and function
One of the most useful distinctions in medico-legal reporting is between prognosis for pain intensity and prognosis for functional capacity. The two are related but not identical.
A claimant may continue to experience pain yet make substantial improvements in mobility, independence, employment, exercise, family responsibilities and quality of life. Conversely, relatively modest pain can be associated with significant disability where avoidance, fear, psychological distress or other factors predominate.
This distinction is supported by rehabilitation literature. Multidisciplinary rehabilitation for chronic low back pain can improve disability and work-related outcomes even where pain does not completely disappear. Exercise similarly provides benefit for chronic low back pain, although average effects on pain and functional limitation are generally modest rather than curative.
A medico-legal expert should therefore be cautious about statements such as: “The claimant will continue to experience pain indefinitely and will therefore remain unable to work.” The first proposition does not automatically establish the second.
A more defensible opinion may be: “Although some degree of persistent pain is likely, there remains reasonable potential for functional improvement through rehabilitation, increased activity, improved self-management and treatment of relevant psychological or sleep-related factors.” For damages purposes this distinction can be extremely important.
What predicts a poorer outcome?
A number of factors are repeatedly associated with persistent pain and disability.
High initial pain intensity is among the more consistent predictors of poor outcome following whiplash injury. Prognostic reviews of whiplash outcomes similarly identify higher initial pain and anxiety as associated with poorer outcome, while evidence supporting many physical factors is weaker.
Psychological factors can also influence prognosis, although experts should avoid treating them deterministically. Poor recovery expectations, post-traumatic stress symptoms and passive coping are among the more consistently reported psychological prognostic factors in whiplash-associated disorders.
Pain catastrophising has received particular attention. Reviews in low back pain suggest that high catastrophising may be associated with delayed recovery, although the strength and consistency of the evidence are imperfect. More recent rehabilitation research in fibromyalgia and chronic low back pain also suggests that catastrophising may predict aspects of pain and self-reported function, although its predictive value is substantially weaker for some objective functional outcomes.
Other potentially adverse prognostic factors include: substantial pre-existing chronic pain; severe and prolonged acute pain; widespread pain; significant depression or PTSD; disturbed sleep; fear-avoidance and prolonged inactivity; poor expectations of recovery; prolonged absence from employment; social adversity; repeated unsuccessful interventions; and major physical comorbidity.
Insomnia deserves particular attention, since longitudinal evidence indicates that significant sleep disturbance can increase the risk of progression from localised pain toward more widespread pain.
None of these factors determines an individual’s outcome. An expert should therefore resist statements such as: “Because this claimant has depression and catastrophising, the prognosis is poor.” The more accurate interpretation is that such factors may increase the probability of persistence or disability, particularly where several coexist.
Protective factors are equally important
Medico-legal reports sometimes identify every adverse prognostic factor but pay insufficient attention to resilience.
A balanced prognosis should consider protective factors including preserved employment, regular exercise, strong social support, psychological stability, adaptive coping, realistic expectations, continued independence and willingness to engage in rehabilitation.
A claimant who remains active, continues working and maintains important social roles despite persistent pain may have a significantly different functional prognosis from an individual with similar pain intensity who has become profoundly inactive and socially withdrawn.
This is particularly important because the aim of chronic pain treatment is often not elimination of all pain. Instead it may involve improved self-efficacy, increased participation, improved sleep, reduced distress and restoration of meaningful activity. Prognosis should reflect the person’s trajectory and adaptability, rather than merely their numerical pain score.
Treatment response cannot be guaranteed
Another common medico-legal difficulty is forecasting the effect of future treatment.
Pain specialists may reasonably recommend physiotherapy, exercise rehabilitation, psychological intervention, medication optimisation, sleep management or multidisciplinary pain rehabilitation. However, recommending treatment is not equivalent to predicting that it will produce a particular outcome. Treatment effects in chronic pain populations are typically variable.
Exercise therapy in chronic low back pain is supported by moderate-certainty evidence for improvements in pain compared with no treatment or usual care, but the average benefits are not necessarily large. Similarly, self-management approaches for chronic widespread pain and fibromyalgia may improve pain and physical function, but the quality of evidence and magnitude of benefit vary considerably. Multidisciplinary biopsychosocial rehabilitation can improve disability and some work-related outcomes in chronic low back pain, but not every patient benefits and complete pain resolution should not be promised.
An expert can therefore state that treatment provides a reasonable opportunity for improvement, but should rarely state that a particular treatment “will” resolve chronic pain. Treatment potential is not the same as treatment certainty.
The claimant’s previous trajectory may be more informative than population averages
In many established chronic pain claims, one of the strongest pieces of prognostic information is the claimant’s own longitudinal history.
Consider an individual whose symptoms have remained essentially unchanged for four years despite appropriate investigation, physiotherapy, medication, psychological support and attempts at rehabilitation. It would generally be difficult to justify predicting complete recovery within the next 12 months unless there were identifiable new circumstances likely to change the trajectory.
Conversely, a claimant who has demonstrated progressive improvement over the preceding year, returned gradually to exercise and employment and reduced medication may reasonably be expected to continue improving.
The expert should therefore consider: is the claimant improving, deteriorating or stable? Has treatment materially changed symptoms or function? Are important modifiable factors still untreated? Has the claimant demonstrated capacity for functional restoration?
The individual’s trajectory may provide more clinically meaningful prognostic information than simply quoting a population recovery percentage.
Duration matters, but does not make prognosis absolute
Duration of symptoms is highly relevant. If pain has persisted for several years, particularly despite appropriate rehabilitation, complete resolution becomes less predictable. It may be reasonable to describe further improvement as possible but complete recovery as uncertain.
What an expert should avoid is converting chronicity into inevitability. The statement “the claimant has experienced pain for five years and therefore it is permanent” is usually stronger than the medical evidence allows.
A more appropriate formulation is: “Given the duration and stability of symptoms to date, I consider complete resolution increasingly unlikely. Nevertheless, chronic pain remains potentially modifiable, particularly in relation to function, coping and activity. I therefore cannot exclude meaningful future improvement.” This properly communicates probability without pretending certainty.
Prognosis in chronic primary pain and fibromyalgia
Prognosis becomes especially challenging in chronic primary pain and fibromyalgia. These conditions commonly fluctuate rather than following a simple linear course from illness to recovery. Treatment is often directed toward symptom management and functional restoration rather than cure.
Research demonstrates substantial individual variation. Even long-term studies of fibromyalgia and chronic widespread pain identify psychological and stress-related characteristics associated with subsequent improvement, but they do not permit reliable prediction for a particular patient.
Accordingly, an expert may reasonably conclude that complete and sustained symptom resolution is uncertain or unlikely in an individual with established widespread pain, yet simultaneously conclude that functional improvement remains realistic. These propositions are not contradictory. Persistent pain does not necessarily imply persistent severe disability.
Prognosis after traumatic injury
Persistent pain can remain present for many years following musculoskeletal trauma, with limitations in the quality and consistency of the available prognostic research well recognised in the literature.
Whiplash is particularly instructive because the literature illustrates the limitations of prediction. Higher initial pain appears repeatedly as an adverse prognostic factor, but experts remain unable to identify a simple biological marker or clinical characteristic that reliably predicts individual recovery. Even sensory abnormalities may change differently between individuals, with altered pain processing improving relatively rapidly in those who recover while persisting in a subgroup with ongoing symptoms.
The expert should therefore describe prognosis probabilistically rather than suggesting that chronic post-traumatic pain follows a predetermined course.
Return to work requires a separate analysis
Pain prognosis and occupational prognosis should also be distinguished.
A pain expert can provide an opinion on functional restrictions attributable to pain, but future employment depends on many factors outside pain medicine, including occupation, employer flexibility, transferable skills, labour-market circumstances, motivation and workplace adaptations.
A claimant who cannot return to heavy manual employment may nevertheless retain substantial capacity for sedentary, administrative or modified work. Conversely, apparently modest physical limitations can have major consequences for someone whose occupation depends on specific physical capabilities.
The expert should therefore avoid conflating “unlikely to become pain-free” with “unlikely ever to work again.” Where vocational consequences are complex, they may ultimately fall partly outside the pain expert’s expertise.
The medico-legal problem with precise recovery dates
Statements such as “symptoms should resolve within 18 to 24 months” appear frequently in medico-legal reports. Sometimes they are justified, particularly during recovery from uncomplicated tissue injury. In established chronic pain, however, such precision may be scientifically artificial.
There is rarely evidence allowing an expert to distinguish confidently between recovery at 18 months, 24 months or 30 months. A broad range may communicate uncertainty better than a falsely precise date.
The expert should ask: what evidence allows me to nominate this particular time period? If the answer is simply clinical custom rather than identifiable biological reasoning, longitudinal evidence or observed improvement, the prognosis should probably be expressed less precisely.
What can the expert say with confidence?
In many chronic pain claims the expert can confidently describe the direction and boundaries of prognosis, even when the exact future course cannot be predicted. For example:
- complete symptom resolution may be less likely after several years of stable chronic pain;
- meaningful functional improvement may remain achievable;
- rehabilitation may improve function without eliminating pain;
- active psychological distress, sleep disturbance or avoidance behaviours may adversely influence recovery;
- worsening is not inevitable merely because pain is chronic;
- structural deterioration should not be predicted without appropriate pathological evidence;
- a particular intervention cannot be guaranteed to restore function; and
- prognosis should be revisited if significant clinical circumstances change.
These are often more useful medico-legally than an arbitrary prediction that symptoms will disappear on a particular date.
The expert’s duty is to express uncertainty, not conceal it
Under CPR Part 35 an expert’s duty is to assist the court, and expert evidence should be confined to matters reasonably required to resolve the proceedings. That duty includes acknowledging the limitations of medical evidence.
Uncertainty is not weakness in expert evidence. Indeed, an opinion may be more defensible when the expert clearly distinguishes between what is probable, what is possible, what cannot presently be predicted, and what falls outside the expert’s expertise.
A pain expert should therefore avoid both unwarranted optimism and unwarranted pessimism.
Conclusion
Prognosis in chronic pain is not an exercise in predicting the precise date on which symptoms will disappear. The scientific evidence rarely permits such certainty.
The pain expert can usually comment more confidently on probability, trajectory, function, modifiable prognostic factors and reasonable treatment potential than on complete recovery. Chronicity increases the probability of persistence but does not prove permanence. Psychological and social factors influence prognosis but do not determine it. Treatment creates an opportunity for improvement but does not guarantee recovery. Persistent pain may coexist with substantial restoration of function.
Perhaps the most useful prognostic question is therefore not “when will this claimant become pain-free?” but “given the condition, duration, previous trajectory, vulnerabilities, protective factors and available treatments, what is the most probable range of future pain and functional outcomes?” The expert should then identify where that opinion is strong and where uncertainty remains.
In medico-legal practice, a carefully qualified prognosis is generally more scientifically defensible than false precision. The purpose of expert evidence is not to eliminate uncertainty where medicine cannot do so, but to explain that uncertainty coherently and to assist the court in understanding what is likely, what remains possible and what cannot reliably be predicted.
Related Insights
- Chronic Pain After Trauma: Causal, Contributory, or Merely Temporal? By Dr Tom Bendinger
- Fibromyalgia Following a Minor Road Traffic Collision: Diagnosis, Causation, and Medico-Legal Risk, by Dr Tom Bendinger
- Catastrophisation, ACEs, and ‘Disproportionate’ Pain, by Dr Graeme Fitzpatrick
- Imaging, Surgery and Analgesia as Poor Proxies for Pain Severity, by Dr Graeme Fitzpatrick
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FAQs
1. Can a pain expert give a precise date for when a claimant will recover?
Rarely, in established chronic pain. Precise recovery dates are usually more justified in straightforward recovery from acute tissue injury than in chronic pain, where evidence rarely allows an expert to distinguish confidently between recovery at, say, 18, 24 or 30 months. A range that communicates uncertainty is generally more defensible than a single date.
2. If a claimant has psychological risk factors such as catastrophising or depression, does that mean the prognosis is poor?
Not on its own. These factors are associated with an increased probability of persistence or disability, particularly where several coexist, but they do not determine an individual’s outcome. A statement like “the prognosis is poor because of catastrophising” overstates what these factors can tell us about one person.
3. If a claimant still has pain, does that mean they cannot work?
Not necessarily. Pain intensity and functional capacity are related but distinct. A claimant can continue to experience pain while making substantial improvements in mobility, independence and employment, and conversely, relatively modest pain can be associated with significant disability. The two should be assessed and reported on separately.
4. Is recommending a treatment the same as predicting it will work?
No. Recommending physiotherapy, psychological intervention or rehabilitation reflects a reasonable clinical opportunity for improvement, not a guarantee of outcome. Treatment effects in chronic pain populations are variable, and an expert should be cautious about stating that a particular intervention “will” resolve a claimant’s pain.
5. Does chronic pain always get worse over time?
No. Worsening is not inevitable merely because pain is chronic, and structural deterioration should not be predicted without supporting pathological evidence. Equally, complete symptom resolution becomes less likely the longer stable chronic pain persists. The most defensible prognosis sits between unwarranted optimism and unwarranted pessimism.
