Challenge to concessions
23The experts were agreed on three propositions central to the determination of an appropriate diagnosis. First, the plaintiff's condition was consistent only with asbestosis or IPF: there was no plausible third option. Secondly, a precondition to a diagnosis of asbestosis was a history of sufficient exposure to airborne asbestos dust. The level of exposure was, to some extent, controversial but Amaca conceded, at least in this Court, that there had been sufficient exposure to satisfy that precondition.
24Beyond these propositions, there were particular diagnostic criteria which were associated with one disease rather than the other. However, absent a biopsy, which was not practicable in relation to the plaintiff, each criterion which might inform a differential diagnosis was indecisive. For example, there was a question as to the likelihood of there being asbestosis, absent pleural plaques. Not only was there debate as to the relative significance of the absence of pleural plaques, but there was disagreement as to whether the plaintiff exhibited that symptom. The criterion which had the greatest potential to permit a diagnosis of asbestosis in the present case was the longevity of the disease. Thus, asbestosis was a condition which progressed slowly (some patients might die with, rather than from, asbestosis), whereas IPF generally progressed much faster. The plaintiff's case was that he had had the disease for at least 12 years and that the probability of a person with IPF surviving more than four or five years was remote: accordingly the correct diagnosis on the probabilities was asbestosis.
25The judge discussed in some detail the history of the plaintiff's medical examinations from May 2007 when he was experiencing symptoms including a cough, a hoarse voice and occasional breathlessness. X-rays were taken at that time, as was a high resolution CT scan. However, it was later discovered that an X-ray had been taken in 2005. That X-ray was shown to Dr Bryant shortly before the hearing. The judge stated (reasons, p 9):
"With that X-ray, Dr Bryant, who did not have it initially when he did his reports, was able to come to the opinion that this man had this disease, asbestosis, as long ago as 2000. That is, it was manifesting itself in 2000. And in his opinion, it could not be idiopathic pulmonary fibrosis because that disease is one of rapid progression and if he had had that in 2000 he would have been dead years ago. It was just not possible for him still to be alive.
Ultimately, Dr Jones, who certainly is an expert radiologist, and Dr McKenzie conceded that if he had this disease as long ago as 2000, it could not be anything but asbestosis."
26In a later passage (reasons, p 10) the judge explained that, given Dr Bryant's very extensive experience and expertise, the fact that he was a treating doctor and that his opinion was backed by Professor Breslin, an eminent authority in the area, he preferred Professor Bryant's opinion to that of Drs McKenzie and Jones. The judge continued:
"To some extent they differ, but they do not differ on the essential matter that this man should have been dead years ago if he had idiopathic pulmonary disease. I therefore have come to the conclusion that he did have asbestosis, he has got asbestosis."
27These statements should be read together: that is the final statement suggesting that Dr McKenzie and Dr Jones accepted that the plaintiff "should have been dead years ago" depended on an assumption as to the point at which he first manifested the disease. Amaca's challenge to these passages was twofold. First, it challenged the characterisation of the evidence of its witnesses as a "concession" in the terms identified by the trial judge. Secondly, it challenged the finding purportedly based on Dr Bryant's opinion that the plaintiff had in fact had the disease "as long ago as 2000."
28It is convenient to refer first to the evidence of Dr McKenzie. He was taken in cross-examination to the X-ray report from 2005 which showed the existence of fibrotic changes: Tcpt, p 202(37). He accepted that the radiologist "described what he saw as coarse increased interstitial markings" and that they "may represent long standing pulmonary fibrosis": p 202(43)-(46). He further agreed that the report was consistent with "the existence as early as 2005 of interstitial disease that was clearly found to be present in 2007." He also agreed that if there had in fact been interstitial disease seen by the radiologist in 2005 "it would have been developing for some years prior to 2005": p 202(50). The cross-examination and answers continued:
"Q. If we make that assumption that the interstitial process had been progressing for some time before 2005 and had progressed to the stage of honeycombing in 2007, which the CT scans demonstrate, it is highly probable is it not that if what Mr Tullipan had was IPF, he would be dead by now. A - Yes, more probable than not, so -
Q. And for that reason it is more likely, is it not, that his fibrosis is a result of asbestosis and not idiopathic pulmonary fibrosis. A - I don't agree that follows.
Q. Well the length of time, if one assumes the fibrosis occurred before 2005 to the present, would make it much more likely, would it not, that what Mr Tullipan is suffering from is asbestosis rather than idiopathic pulmonary fibrosis. A - I disagree with that. I would say if someone had asbestosis in 2005 with normal lung function in 2005 the chance of that person being dead from asbestosis in 2014 I would say is well less than 10%. I would say that it is very, very unlikely. Whereas I think there is probably a 20 to 30% chance that someone could have idiopathic pulmonary fibrosis for that long."
29The denial with which the last answer commenced was contradicted by the explanation. Treating the survival rate as the obverse of the mortality rate, the survival rate for a person with asbestosis was 90%. The highest survival rate proffered for a person with IPF was 30%. That is, a person having pulmonary fibrosis in 2005 and surviving to 2014 was at least three times as likely to be suffering from asbestosis as IPF. Those figures more than satisfy a standard applying the balance of probabilities. That constituted a sufficient concession to warrant the remark by the trial judge. Nevertheless, the cross-examiner returned to the fray shortly thereafter eliciting the following answers (p 204):
"Q. Professor, if the plaintiff had fibrosis as early as about 2003, and if he was suffering from idiopathic pulmonary fibrosis as you have said, if he is still alive now, that would be an unusually long survival time for the condition. A - Yes it would.
Q. Most would be dead years ago. A - Yes. ...
Q. Mr Tullipan's survival from an apparent onset of fibrosis in 2003 to the present is more consistent with asbestosis than with idiopathic pulmonary fibrosis, do you agree with that proposition. A - Yes, I think I will agree with that."
30The cross-examiner undertook a similar line of questioning with Dr Jones, ending with the following exchange (p 144):
"Q. If Mr Tullipan had fibrosis as early as 2003 and if he in fact was suffering from idiopathic pulmonary fibrosis, that would be an unusually long survival time would it not. A. - Yes it would.
Q. And that survival time and that circumstance would be more consistent I would suggest with asbestosis than with idiopathic pulmonary fibrosis. A. - Yes it would.
31Dr McKenzie, dealing with the passage of eight or nine years, treated the survival rate in IPF sufferers as no greater than 30%. Dr Jones gave evidence that the mortality rate from IPF at five years was 70% and the survival rate 30%: Tcpt, p 143(14). The finding by the trial judge as to agreement that the plaintiff "should have been dead years ago" if he had IPF was imprecise and involved an unnecessary element of hyperbole. It did not, however, involve any material error. It is correct to say that neither Dr Jones nor Dr McKenzie conceded that "if he had this disease as long ago as 2000, it could not be anything but asbestosis." This statement involved two errors, but neither of them assists Amaca. First, Dr McKenzie used a period from the date of the first X-ray in 2005. (Counsel may have been confused by the figures cited and not realised it was a powerful concession.) In the second passage, Dr McKenzie accepted the probability when the disease was measured from 2003. Counsel used the same year, 2003, in obtaining the final concession from Dr Jones. He may also have failed to appreciate that Dr Jones gave a survival rate of 30% at five years, which would have been satisfied by going back no further than 2007. Thus, it would have been sufficient for Mr Tullipan's purposes if the concessions had been identified by reference to a disease commencing in 2003: however, the concession would have strengthened rather than diminished by going back to 2000. More importantly, with respect to Dr McKenzie, reliance on 2005 would have been sufficient because he accepted that the disease in fact would have developed some years prior to 2005. The error was therefore harmless.
32This analysis assumes that the relative frequencies of asbestosis and IPF were comparable, an assumption consistent with the concessions. It should also be noted that the analysis relevant to competing causes for a known disease may be quite different from that applicable to the differential diagnosis of an unknown disease, where there are only two competing candidates: cf Amaca Pty Ltd v Ellis [2010] HCA 5; 240 CLR 111 at [56], [64] and [70].
33The second error was a case of hyperbole. Neither witness said "it could not be anything but asbestosis." In fact, both witnesses adhered to the view that it could be IPF. Each did so on the apparent basis that if some might live longer than five years with IPF, that possibility remained open. Dr Jones said "the time scale [for IPF] is something like 12 years": p 143. By "time scale" he appears to have meant something like the longest possible period of survival absent exceptional circumstances. The plaintiff's case, however, had to be determined on the balance of probabilities and not by the exclusion of mere possibilities.
34The final step in the reasoning required that there be evidence to support the finding that formed the basis of the concessions, namely that Mr Tullipan had fibrosis "as early as 2003". Amaca challenged the finding, supposedly based on Dr Bryant, that the disease had arisen "as long as 2000." Dr Bryant did not give such evidence, according to the appellant. Amaca submitted that the finding by the trial judge was based on a misreading of the following evidence (Tcpt, p 30), where Dr Bryant had stated:
"My opinion was that ... because the honeycombing was detected in 2007, that it's likely that this condition has been going for at least some years irrespective of the 2007 chest X-ray which I've only just become aware of. So I felt that this suggested that the condition that we're observing now had its genesis back sometime in the period in the early years of 2000." (Emphasis added.)
35Amaca's point was that "the early years of 2000" meant somewhere between 2001 and 2004, perhaps, but not "as long ago as 2000". If this were a factual error, it would have been immaterial because this evidence was at least consistent with a disease dating from 2003, which was the basis of the relevant concessions. However, there was no factual error. One point that Dr Bryant appeared to be making was that he had reached that conclusion as to the genesis of the disease without having access to the 2005 X-ray. He gave further evidence in cross-examination (Tcpt, p 176) in the following terms:
"... if he had a highly abnormal chest X-ray and CT scan back in 2005 or 2007 but normal lung function, and if the disease has been progressing since that time at the same rate that it was beforehand and there is no reason to assume that it is an incorrect proposition, then it has taken him nine years to go from having few, if any symptoms to being at death's door. Presumably that means that the condition was present for five or ten years beforehand, so we're talking about a disease which is progressing actually very slowly, it's taken nearly 20 years from the probable time of onset of his disease for him to die. Now I have never seen a patient with IPF do that."
36Shortly thereafter, adhering to that reasoning, he suggested that the disease had actually been present "for a substantially longer period than [from] 2005" but said, "I can't tell you [how] long." This evidence supported the finding that Professor Bryant held the opinion that the disease had commenced "as long ago as 2000". The evidence of Professor Breslin, set out by Leeming JA, was to similar effect: Tcpt, p 88(27).
37The trial judge decided the case on the basis of the three factors referred to above. The first two (sufficient exposure to asbestos and the absence of any third possibility) were not in dispute. The third factor was longevity. The principal witnesses for Amaca accepted, on the balance of probabilities, based on the known mortality and survival rates for the two conditions, that longevity demonstrated that the disease was more likely to be asbestosis. The trial judge was entitled to accept that evidence and determine the case on that basis. To do so demonstrated no error in point of law (or fact). Accordingly, as counsel for Amaca conceded, if it failed on that challenge (which it does) the appeal with respect to liability must be dismissed (as it was). The other issues do not arise.
38I agree with the further reasons of Leeming JA on this matter.