Missed medical diagnoses and the case for permitting proportionate recovery under English Law

Transcription

1 17 CURRENT CONTROVERSIES Missed medical diagnoses and the case for permitting proportionate recovery under English Law M Stauch Journal of Academic Legal Studies 2005;1:17 21 Correspondence to: Marc Stauch, MA (Oxon) Solicitor, Lecturer and Researcher, Centre for British Studies, Humboldt-Universität zu Berlin Jägerstraße 10-11, D Berlin This paper looks at the problem of factual causation in the context of medical negligence claims centred on the failure to diagnose illness - a problem recently revisited by the English House of Lords. It is argued that in appropriate cases the law should allow proportionate recovery in line with the statistical chance of a cure lost by the patient. INTRODUCTION A fairly common type of problem within the field of medical negligence law concerns the availability of compensation for missed or mistaken diagnoses by doctors. If the patient wishes to recover damages against the doctor, there are two significant hurdles he must overcome. In the first place he has to show that the doctor was at fault i.e. that a reasonably careful doctor would have correctly diagnosed the patient s condition. In practice this is often no easy thing for the patient to do: the courts recognise that, even today, with the aid of complex diagnostic tests and equipment, diagnosis remains an imprecise business, and are cautious apart from in clear cases- about finding a doctor, who happens to have missed a diagnosis, at fault. Nevertheless, for the purposes of this paper, it will be assumed that fault has been established in a given case. For our concern here is with the second major obstacle that the patient must overcome the hurdle known as causation. 1 THE CAUSATION ELEMENT Causation in the tort of negligence is typically resolved by means of the but for test. As Denning LJ once put it, [i]f the damage would not have happened but for a particular fault then that fault is the cause of the damage; if it would have happened just the same, fault or no fault, the fault is not the cause of the damage. 2 The Court here constructs a parallel series alongside - and by way of contrast to - events as they actually occurred. Beginning with the (counterfactual) assumption that the defendant properly performed his duty, it will ask how matters would then have turned out. A good example, in the context of medical negligence, is provided by the case of Barnett v Chelsea and Kensington Hospital Management Committee. 3 There a night watchman went to the defendant s hospital when he became ill after drinking some tea. However, the casualty doctor failed to examine him and he died a few hours later from what turned out to be arsenic poisoning. In the subsequent action in negligence, brought against the hospital by the man s widow, the doctor was found to have breached his duty; however her claim failed for lack of causation. The doctor s fault the Court held- had made no difference to the ultimate outcome. Given the difficulty of diagnosing arsenic poisoning, the clear likelihood was that, even if the doctor had acted properly and examined the man, his condition would have been discovered too late to effect a cure: he would have died anyway. In principle, it is clear why the law insists upon the need for causation before awarding compensation. If it were not so, claimants would receive a windfall damages for a misfortune that it was not in the defendant s (or anyone else s) reasonable power to prevent. At the same time, though, in the context of missed medical diagnoses, the hurdle often presents serious difficulties for patients. This is because the patient -at the time of the doctor s faulty mistake- is typically already at risk of suffering injury (as a result of the illness that led him to seek the doctor s help). Thus the doctor can always argue that his admitted breach of duty made no difference; that the illness, even with all proper medical skill, could not have been treated effectively. PROOF ISSUES This brings us on to the rules of evidence in relation to private law claims (including those for medical negligence). As already noted, the underlying substantive issue is relatively straightforward: if the patient s illness was treatable, then the faulty misdiagnosis (denying the opportunity for such treatment) caused the ultimate injury. If the illness was not treatable, then, as in the Barnett case, there will be no causation and no liability. The real problem is evidential in nature: could the illness on the facts have been treated or not? Prima facie, it is the patient who has the burden of satisfying the court that his condition was treatable. This is in accord with the idea that it is he (as claimant) who is inviting the Court to disturb the status quo by ordering compensation. Sometimes, this task may present little difficulty: the judge, having heard the views of the competent medical

2 18 experts on the matter, may be in no doubt at all that, had a proper diagnosis been made, correct treatment would have followed and achieved a complete cure. But in many other cases, it may be much more difficult to say what would have happened: the scientific evidence about this may be unclear. Of great significance here is the standard of proof i.e. the degree to which the judge must be persuaded that the patient s assertion is true. In accordance with English private law generally, this standard is that of the balance of probabilities : the court must think it more likely than not that, had a proper and timely diagnosis occurred, effective treatment would have been available. If this proof threshold is met, the patient will be entitled to full compensation for his injuries; but if he fails to meet it, he will end up with no compensation at all. In this sense, the balance of probability standard embodies an all or nothing approach. It is apparent that such an approach, applied to causation, is not necessarily fair, especially when there is real doubt about what would have happened if the defendant had acted properly. Rather the law demonstrates a rough and ready pragmatism (to avoid the expenditure of too much time and effort on investigating various hypothetical possibilities). Sometimes it is the doctor who may suffer from this: he will end up paying for an injury, even though there was a good chance that it would have occurred anyhow. But more often it is the patient, as the party with the burden of proof, who will lose out: he will get nothing in cases where, though there was a good chance that treatment would have prevented his injury, he cannot show positively that it probably would. Exceptionally, outside the medical negligence context, the courts have been prepared to relax the proof rules in cases of causal uncertainty so as to assist claimants in negligence actions: they have done so by holding that, provided the claimant shows that the defendant s fault exposed him to a significant risk of the harm he suffered, the burden of proof may sometimes shift to the defendant to disprove causation. 4 Nonetheless, this approach has been expressly rejected in relation to medical negligence claims. 5 Nor would it get to the heart of the problem posed by causal uncertainty in medical non-diagnosis cases: to require the doctor to pay simply on proof that his failure to diagnose and treat exposed the patient to a risk of injury something generally true 6 - would often give rise to a windfall. The patient will end up compensated in cases where there was in fact nothing that could have been done for him. It is submitted that the underlying problem in such cases is the adherence to the all or nothing balance of probabilities proof standard. This might be acceptable if there were nothing better on offer. However, in the context of missed diagnoses, there is usually detailed evidence available as to the effect that the doctor s mistake had upon the patient. Such evidence takes the form of class statistics compiled in relation to other patients with a similar medical condition to the claimant, who were given the appropriate treatment: the statistics record what percentage of such patients responded to the treatment (and hence avoided ultimate injury), as opposed to those who went on to suffer the injury anyway. Unfortunately, as we shall see, the House of Lords has so far refused to accept this form of evidence. CLAIMS FOR PROPORTIONATE RECOVERY BASED ON LOST STATISTICAL CHANCES In Hotson v East Berkshire AHA, 7 the patient was a schoolboy, who attended the defendant s casualty department after falling from a tree and injuring his hip. The defendant failed, in breach of duty, to carry out an X-ray of the hip and, by the time the extent of his injury was discovered, permanent disability was unavoidable. The medical evidence as to causation was to the effect that, with immediate diagnosis, 25 per cent of patients with such an injury could be successfully treated, while 75 per cent went on to develop the same disability anyway. On these facts, the High Court and Court of Appeal accepted the patient s claim for the loss of the residual 25 per cent chance that prompt diagnosis and treatment would have prevented his disability, and awarded him proportionate recovery for it. 8 However, the House of Lords unanimously allowed the health authority s appeal and reasserted the need for the claimant, in medical negligence cases, to prove causation of the injury itself on the balance of probabilities. Recently, in Gregg v Scott, 9 the House of Lords had another opportunity to consider the merits of a claim couched in terms of the loss of a statistical chance. There the claimant had consulted the defendant doctor in 1994 about a lump under his arm. The latter assumed that it was benign and negligently failed to refer him to hospital for tests. It was not until the claimant was admitted to hospital over a year later that he was found to be suffering from non-hodgkin s lymphoma. The effect of the delay in diagnosis was that the cancer had spread and, statistically, the claimant s chance of a cure (defined, medically, as ten-year diseasefree survival) had fallen from 42 to 25 per cent. The claimant subsequently underwent a number of painful and distressing treatments, but at the time of the House of Lords hearing -nearly ten years after the original misdiagnosis- was still alive. The lower courts, following Hotson, denied the claimant s claim for the reduction in his statistical chance of

3 19 recovery and his appeal to the House of Lords was dismissed by a three: two majority. 10 PROPORTIONATE RECOVERY VS. THE BALANCE OF PROBABILITIES Underlying the rejection by the House of Lords of the claim for proportionate recovery in Hotson and (by the majority) in Gregg, three main reasons can be discerned. First, there is a distrust of statistical evidence (on which such claims are founded) per se. Secondly, there is concern that allowing such recovery will undermine the general rules in relation to causation in personal injury cases. Thirdly, there are specific concerns about making recovery of damages against doctors too easy and the consequent drain on NHS resources. It is submitted that none of these reasons is ultimately convincing, and that in fact the use of statistically based proportionate recovery for faulty medical diagnoses has much to commend it. At the same time, it will be suggested that the decision to deny liability in the Gregg case was correct: (1) Concerns as to the merits of statistical evidence First, as to their Lordships distrust of statistical evidence, it is true that such evidence does not offer certainty in any individual case. As Lord Nicholls noted in his dissenting speech in Gregg, Statistics record retrospectively what happened to other patients in more or less comparable situations. They reveal trends of outcome. They are general in nature. The different way other patients responded in a similar position says nothing about how the claimant would have responded. 11 The crucial point here is that the traditional balance of probabilities is no different: in finding that a given patient could more likely than not have been cured of a given condition, the court is just as reliant upon experience as to how other patients with a similar condition responded to treatment (here that more end up cured than not cured). It does not tell us that the claimant individually would have been successfully treated: he might, for all we know have been one of the (perhaps very sizeable) minority who could not have been. In awarding full compensation in each such case, the present law produces many a windfall; moreover this occurs at the expense of patients in other cases who fall the wrong side of the line (because their condition is one which experience shows is more often than not untreatable). The latter currently receive nothing at all, even though a particular claimant might for all we know have been one of the (perhaps very sizeable) minority who could have been treated. Admittedly, the statistical evidence may sometimes be complex or disputed. The medical experts may disagree as to the precise stage or nature of the claimant s condition (at the time that the diagnosis should have occurred), and hence as to the relevant comparator class of patients whose experiences with the proper treatment provide the statistical starting point. Here, the judge, having heard the expert witnesses, must do his best to attach a plausible percentage figure to the chance lost. 12 What is important, however, is that some statistical evidence is available. By contrast, there is no basis for extending proportionate recovery to other cases, i.e. simply in accordance with the subjective feeling of the judge. To allow the latter to conjure percentages out of the air would generate a great deal of speculative litigation for little return. The argument for holding to the pragmatic balance of probabilities approach is here compelling. 13 (2) Concerns as to undermining the general rules of causation As just argued, the proportionate recovery approach requires statistical evidence to be available. By the nature of things this means that it would be confined almost entirely to medical misdiagnosis cases. There in the normal run of events (i.e. apart from misdiagnosis cases), the treatment will have been provided, allowing its success or otherwise to be recorded over a range of similar cases. By contrast, other negligence cases (especially when the defendant s fault takes an active form) are much less amenable to a statistical evidential approach to causation. 14 Moreover, to the extent that the statistical approach is used, it is important to see that the but for test still remains the underlying substantive test of causation. Proportionate recovery in line with statistical evidence is simply a response to the evidential uncertainty that may attend the test s application. Consider, for example, a patient who becomes deaf following the faulty non-diagnosis (and non-treatment) of his meningitis, where the only evidence available is statistical and shows that 30 per cent of patients with that type of meningitis avoid deafness if properly treated. On the proportionate recovery approach, the patient would receive 30 per cent of the damages for the deafness itself. However, suppose now that in this particular case new evidence suddenly became available proving that, with proper treatment, this patient would definitely have avoided deafness. No one would any longer be inclined to award damages by percentages. Given the certainty of but for causation in the particular case, we would pay out full damages. This reveals a further important precondition for allowing proportionate recovery based upon statistics: there should be no better (individuating) evidence available. A further and different concern is that the law, if it allowed claims expressed in terms of chances of outcomes, would be driven to compensate for purely notional injuries i.e. injuries that have not occurred by the time of the trial and may never do so, but whose statistical chance of occurrence has

4 20 been increased by the defendant s fault. 15 We should make it clear at once that such a development is neither inevitable nor desirable. To allow recovery for exposure to risk alone in default of any tangible damage- would be a very radical departure from the rules of negligence liability: the law s concern is with actual, not possible injury. This, it is suggested, was the major flaw in the claimant s case in Gregg v Scott. There, as noted, the statistical evidence showed the defendant s fault had increased the risk of the actionable injury (the claimant s death within ten years) from 58 per cent to 75 per cent. However, there remained a 25 per cent chance that the injury would not occur: indeed by the time of the House of Lords trial, its nonoccurrence seemed quite likely. 16 By contrast, there is no such objection to the classical Hotson type of loss of chance claim. Actionable damage in that case the claimant s permanent hip disability- had occurred: the difficulty was attributing it causally to the defendant. (3) Concerns as to the possible increase in litigation/recovery against doctors Finally, there is the concern that permitting claims for proportionate recovery in misdiagnosis cases would lead to an increase in litigation, and create a further drain upon National Health Service resources. Here, it is vital to appreciate that, in terms of overall compensation, the NHS would pay out no more in respect of faulty diagnosis claims than before: this is because the use of statistics as a basis for proportionate recovery must cut both ways. 17 As suggested earlier, this is inherent in the use of statistical evidence instead of the all or nothing balance of probabilities approach. Thus, for example, in a case where the evidence is that, had a proper diagnosis occurred, the patient would have had a 70 per cent chance of avoiding the disability he suffered, the patient would not receive full (i.e. 100 per cent) damages as at present. Instead, his damages should be discounted to reflect the 30 per cent statistical chance that the treatment would not have helped him anyway. 18 Admittedly, the overall volume of claims may increase as patients will no longer be deterred, as at present, from litigating in non-diagnosis cases where their chance of successful treatment stood at less than the 51 per cent balance of probabilities threshold. To prevent a proliferation of lower-value claims, the law in pragmatic vein should arguably require, at least to start with, that the statistical chance lost was significant, e.g. in the order of 10 per cent or more. 19 CONCLUSION This article has explored the background to the causation difficulties faced by patients in medical misdiagnosis cases and argued that proportionate recovery based on statistical chances should be preferred to the present all or nothing balance of probabilities approach. In doing so it has sought to refute some of the main concerns about the use of statistical evidence that are sometimes raised. Provided that such evidence is to hand and there is no better evidence as to the effect of the misdiagnosis upon the patient, it should be used. At the same time, it is vital that the injury should have occurred by the time of trial. This last point was fatal to the claim in Gregg v Scott; however, it should in no way deter future claimants from bringing Hotson-type claims. 1 Causation is here shorthand for factual causation. (The other aspect of causation in negligence, legal causation, is not relevant for the purposes of this paper.) 2 Cork v. Kirby Maclean Ltd, [1952] 2 All ER 402 (C.A.). 3 [1969] 1 QB 428 (H.L.). 4 Bonnington Castings Ltd v. Wardlaw, [1956] AC 613 ( H.L.); McGhee v. National Coal Board, [1972] 3 All ER 1008 ( H.L.); Fairchild v. Glenhaven Funeral Services, [2002] 3 WLR 89 ( H.L.). 5 Wilsher v. Essex AHA, [1988] 1 All ER 871 (H.L.) (affirmed in Fairchild v Glenhaven Funeral Services, [2002] 3 WLR 89 (H.L.). 6 Admittedly, the faulty diagnosis does not create the original risk of injury to the patient (which is the illness); but it adds to the risk by denying or reducing the chance of effective treatment. 7 [1987] 1 AC 750 (H.L.). 8 The full injury to the hip was valued at 46,000: accordingly the claimant was awarded damages of 11,500 for the lost chance. 9 [2005] UKHL 2 (H.L.). 10 Lords Hoffmann and Phillips and Baroness Hale; Lords Nicholls and Hope dissenting. 11 [2005] UKHL 2 (H.L.), paragraph Such difficulties should not though be exaggerated: the Courts are adept at resolving such disputes in the context of quantifying damages. Moreover, there will frequently be a large measure of agreement among the experts. 13 In such a case.

5 21 14 There are, for example, most unlikely to be statistics that show the effects of over-saturating a patient with oxygen (as occurred in the medical negligence case of Wilsher). 15 For example, the defendant negligently exposes the claimant to a hazardous substance, but not everyone is adversely affected by it and any such effects do not appear until years afterwards. 16 I.e. the claimant had quite possibly not lost a chance: while, statistically, it made a difference for 17 per cent of patients with a similar condition, whether diagnosis took place at the earlier stage (when it should have occurred) or only later, it seemed increasing likely that he was not in that group. 17 Per Baroness Hale in Gregg v. Scott [2005] UKHL 2 (H.L.), at paragraph In a few cases, judges at first instance have engaged in this type of discounting: see Clark v. MacLennan, 1 All ER 416 (Q.B., 1983), Bagley v. North Herts HA, 136 NLJ 1014 (Q.B., 1986), and Judge v. Huntingdon HA, 6 Med LR 223 (Q.B., 1995). 19 In Hotson, the lower courts would have restricted loss of chance claims in this way.