The case of Watson involved disputed factual issues relating to causation, with the central question being whether the Defendant’s admitted breach of duty in failing to include a transient ischaemic attack (TIA) in the differential diagnosis and in turn to prescribe Aspirin would have prevented the Claimant suffering a stroke several months later. The judgment illustrates the detailed forensic analysis which will be applied to the evidence of the lay and expert witnesses at trial in order to determine factual issues of this kind, and the difficulties which a party will face when such evidence is found to be deficient.
The claim arose from a severe stroke which the Claimant suffered in May 2015. The Claimant had attended the Accident and Emergency department at the Defendant Trust’s hospital on 27 March 2015 and alleged that she was suffering from a TIA at this time. Her case was that if (as the Defendant admitted) a TIA should have been included in the differential diagnosis and she would have been prescribed Aspirin, the stroke which she subsequently suffered would probably have been avoided. Causation was disputed by the Defendant on the basis that the Claimant had not suffered a TIA when she attended on 27 March 2015, but rather that she was suffering from migraine. The Defendant accepted that with a differential diagnosis of TIA the Claimant would have been seen in the emergency TIA clinic within the next 24 hours. However, a TIA would have been excluded from the diagnosis on further investigation by MRI scan and Aspirin would then have been stopped, so no damage was caused by the breach of duty. In the alternative, even if the Claimant had in fact suffered a TIA and had continued to take Aspirin, the Defendant maintained that this treatment would not have prevented the stroke on 27 May 2015 and so the Claimant would have suffered the same injury in any event.
Certain facts about the Claimant’s presentation on 27 March 2015 were in dispute. In particular, the Claimant and her partner (Michael Eastham) both referred in their statements to the left side of her face “drooping” and Mr Eastham in his oral evidence referred to the Claimant suffering left leg weakness. It was common ground that the Claimant also experienced weakness in her left arm, but there was a dispute about the onset of this and whether it occurred some time after the onset of the other symptoms The Defendant relied on the contemporaneous medical records in this regard as well as the evidence of Dr Osborne, the doctor who saw the Claimant in the Accident and Emergency department at the hospital.
Both parties relied on expert evidence from neurologists, Professor Brown for the Claimant and Dr Sare for the Defendant. The expert evidence went to assist the Court in determining, after the event, what was the actual diagnosis for the Claimant’s condition on 27 March 2015 taking into account (amongst other things) the findings about her presentation at this time. Professor Brown favoured a diagnosis of multiple TIAs which had, in turn, precipitated migraine, whereas Dr Sare advised it was more likely that the symptoms were due to a type of migraine known as sporadic hemiplegic migraine. The experts also disagreed about whether (if the Claimant was found to have suffered TIAs on 27 March 2015) the beneficial effects of taking Aspirin thereafter would have prevented a secondary stroke in May 2015.
The trial had been adjourned twice due in part to the Covid pandemic and in part because the Claimant wanted to give her evidence “live”. However, on the first day of the trial, the Claimant asserted that she did not have the capacity to give evidence and applied to rely on her witness statement. She relied on letters from her treating neurologist in this respect. The judge, Mr Justice Ritchie, ruled that she could rely on the evidence in her statement, but reserved his position about the weight to be attached to her written evidence.
The issues for consideration were agreed as follows:
The Claimant accepted that if the Court found that her presentation on 27 March 2015 was not due to TIA, then her case would fail (para 15).
Findings about the Claimant’s presentation on 27 March 2015: issues (i) and (ii)
The judge analysed in detail the Claimant’s own evidence, Mr Eastham’s evidence, and Dr Osborne’s evidence before making findings of fact on the first two issues.
The judge considered first the evidence of Dr Osborne (para 31). He found that she was “a careful, fair, logical, intelligent, straight forward, well prepared and impressive witness” and that her clinical notes were clear. He noted that those notes were chronologically set out and recorded a history of right–sided facial droop and the Claimant’s loss of use of her left arm about 15 to 20 minutes into the episode. Based on his impression of Dr Osborne as a witness and from the way her notes were set out he found that her evidence was “credible and logical”.
As to the Claimant’s evidence, the judge identified various “oddities” in it (para 32). He noted as well that she had not been questioned on her evidence. This led him to conclude that the evidence in her witness statement could not outweigh the evidence of Dr Osborne. The “oddities” in the Claimant’s evidence which the judge identified included the following points:
Discrepancies were also identified within Mr Eastham’s evidence. Principally, these were that his evidence about the Claimant having a left–sided facial droop and the timing of when he saw her left arm weakness was different from Dr Osborne’s clinical notes; and that he had asserted in his oral evidence that the Claimant had suffered left leg weakness, but this was not referred to in his witness statement or in the Particulars of Claim. The judge found that he was an honest witness, but concluded that Dr Osborne’s evidence was to be preferred where it differed from that of Mr Eastham (paras 33-34).
This analysis led the judge to find on issue (i) that the Claimant had experienced a right-sided facial droop, and on issue (ii) that the Claimant’s presentation on 27 March 2015 was as stated by Dr Osborne and recorded in her clinical notes including the somewhat later onset of left arm weakness.
Finding on the March 2015 diagnosis: issue (iii)
The judge preferred the evidence of Dr Sare for the Defendant and accepted her opinion that the probable cause of the Claimant’s symptoms on 27 March 2015 was hemiplegic migraine, as opposed to Professor Brown’s opinion that they were caused by multiple TIAs triggering migraine (paras 121-122).
In making this finding, the judge relied (amongst other things) on the factual findings above about the Claimant’s presentation on 27 March 2015 which showed a “march of symptoms” and which in turn (according to Dr Sare at least) were characteristic of hemiplegic migraine but not of multiple TIAs. As with the witnesses of fact, the judge analysed in detail the evidence of the respective experts in their reports, joint statement, and oral evidence. He concluded that Dr Sare “applied clearly explained logic in a way that impressed me in the report and in her evidence” (para 103). By contrast, his assessment of Professor Brown’s evidence was that his “explanations became too complex; his analysis was less than adequate and … his evidence became contorted in relation to where the TIA lesions were in the brain” (para 77). The judge was also critical of Professor Brown’s failure to carry out an adequate analysis of the literature which he relied on in relation to issue (iv) (see below); of his having “descended into the factual evidence in a less than impartial manner by seeking to play up Mr Eastham’s evidence” (para 77); and of his “lack of clarity of thought. He struggled to provide a coherent theory to support his conclusion that the march of symptoms was symptomatic of multiple TIAs” (para 78).
Factual Causation – would the stroke probably have been prevented etc: issue (iv)
Given his finding on issue (iii) above, the question of whether the stroke on 27 May 2015 would probably have been prevented or made minimally injurious as a result of the Claimant taking Aspirin was no longer relevant. However, the judge provided his conclusions on factual causation should they become necessary.
This issue turned primarily on the evidence of the expert neurologists and on their analysis of a paper by Rothwell et al (2016) which it was agreed is the most useful medical literature about the effects of Aspirin use in the first three months after TIA. Professor Brown relied on the Rothwell paper as supporting his opinion that the stroke would probably have been prevented if the Claimant had taken Aspirin. Dr Sare, however, advised that the Rothwell paper was of little relevance for a patient in the particular position of the Claimant.
Again, the judge subjected the competing experts’ opinions and the evidence in the medical literature to detailed analysis. He identified the key issue as being “how do the Rothwell results relate to the Claimant?” (para 135). Given the various relevant factors, including the Claimant’s age, gender, cause of clot and risk factors, he concluded that the Rothwell paper did not provide sufficient evidence to prove factual causation, and hence that the Claimant had not discharged the burden of proof on this issue (para 145).
Given his findings of fact on issues (i) and (ii), and having in turn decided issue (iii) in the Defendant’s favour, the judge dismissed the claim and entered judgment for the Defendant with costs.
Jonathan Hand QC, a barrister in our Clinical Negligence team commented on the case as follows:
The judgment in this case is a helpful illustration of some of the factors which will influence a judge when resolving issues between the lay and expert witnesses at trial and which in turn (as is often the way in clinical negligence litigation) will determine the overall outcome on liability.
Amongst other things, the judge here was influenced by inconsistencies between the evidence of the lay witnesses and the contemporaneous records as well as the pleaded case; by the failure of a witness (the claimant) to give oral evidence and to provide an adequate explanation for this failure; and by whether or not a witness presented as careful and logical in their evidence. In relation to the expert witnesses, the judge subjected their evidence to a very detailed analysis, with one expert faring far better than the other. Perhaps the most striking feature of this analysis is the danger of relying on medical literature which appears supportive in general terms in relation to causation, but which on closer examination does not fit adequately with the particular circumstances of the case or the individual claimant.
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