Informed consent and the newborn

BRITISH MEDICAL JOURNAL VOLUME 293 documented as an objective record of follow up. These photographs are always taken through dilated pupils since the failure rate is otherwise unacceptably high. We would deprecate strongly the suggestion that a camera of this nature can replace the proper examination of the diabetic eye, through dilated pupils, by direct ophthalmoscopy. The only safe alternative to clinical examination is to use the camera to photograph the peripheral retina as well as the macular areas: this is technically possible but in our experience is difficult and time consuming, requires at least four photographs taken by a competent photographer, is less accurate than ophthalmoscopy, and gives unsatisfactory films in some patients. Using the camera in this fashion will effectively negate any advantages in time and cost effectiveness which are claimed for the machine. Thus the advent of the camera does not, and should not, remove the onus placed on the diabetologist to justify his title as a doctor with special skill in diabetes. The title implies a competence to examine the eye clinically and detect and assess the importance of retinopathy. For physicians who feel that they lack this competence time is better spent in becoming adept with the ophthalmoscope rather than poring over photographs-or sending them to the ophthalmologists to interpet. T BARRIE A C MACCUISH Diabetic Unit, Glasgow Royal Infirmary, Glasgow G3 OSF 1 Scobie IN, MacCuish AC, Barrie T, Green FD, Foulds WS. Serious retinopathy in a diabetic clinic: prevalence and therapeutic implications. Lancet 1981;ii:520-1. 2 Foulds WS, MacCuish AC, Barrie T, at al. Diabetic retinopathy in the west of Scoland: its detection and prevalence, and the cost-effectiveness of a propoaed sreening programme. Heakh BuL (Edinb) 1983;41:318-26. 3 Deckert T, Poulsen JE, Larsen M. Prognosis of diabetics with diabetes onset before the age of 31. Diabewtoa 1978;14: 363-70. Informed consent and the newborn SIR,-Since Dr Richard Nicholson (25 October, p 1099) avoids the main issue raised in my letter (30 August, p 562) 1 must challenge him to answer it. Randomised trials of different treatments are fundamental to our efforts to reduce mortality and handicap in babies. When it is impossible to obtain prior informed consent from parents of sick babies should such babies be excluded from trials or not? I and many other paediatricians would welcome wide public debate about this, since if trials are not done or such babies are excluded from them advances in treatment will inevitably be slowed. When prior discussion with parents cannot take place because they are absent, unconscious, or in a state of shock a choice must be made between two priorities: the need to prevent death and disability or the rule of prior informed consent. Faced with this dilemma I think that society and parents in general will want trials to go ahead, provided they have the considered, independent approval of a properly constituted ethics committee (not composed of doctors alone). Some comment is needed on tne headlines about "experimenting on babies" for which Dr Nicholson acknowledges responsibility. For many, far from the rigorous comparison of treatments entailed in a randomised trial, that phrase implies the infliction of unacceptable procedures to which few parents would ever consent. Perhaps Dr Nicholson did not intend that the public should be misled by this ambiguity and the distress which it has inevitably evoked. If he did not he should certainly say so. Those headlines have clouded a particularly sen- sitive issue. Oxford OX4 2NL 15 NOVEMBER 1986 Computer aided diagnosis of acute abdominal pain SIR,-The findings of Dr I D Adams and others (27 September, p 797) seem to have promoted the opening of many an old wound (18 October, p 1025). We believe that the abdominal pain diagnosis trial should be assessed for its positive contribution to medical practice, without prejudice. Although it may be difficult for many doctors with traditional training to accept that the computer has any contribution to make in medicine,' other than perhaps in administration, it would be a mistake to discard the potential advantage of its use in diagnostic support without reference to the evidence. The role of the computer in this study should not be underestimated. It was used, appropriately, to examine and remember the fine detail of several thousand hospital case records. It was then able to define precisely, for each age and sex category, the relation between signs, symptoms, and the diseases of acute abdominal pain. As the human information processor is not capable of handling such quantities,2 it could perhaps be argued that each doctor uses a best estimate of this information when tackling diagnosis. It could be concluded that the main benefit of the use of the computer is to provide interactive exposure to its precise diagnostic relationships. Ihis exposure has the benefits of focusing the mind of the non-specialist on the important points of the history and emination and providing a solid foundation on which individual diagnostic stratagems can be based. In this way the computer provides a condensed supplement to the small number of cases which a non-specialist can be expected to see during training. In clinical practice, the implications are that the casualty officer or general practitioner could use a computer such as described in the article to help with management decision making through its highlighting important features that may have been overlooked. In a modified and "safer" form this type of diagnostic program is being used by paramedics at sea for medical decision support. The applications and their implications need to be explored, discussed,3 and developed, where appropriate, to our advantage. G J BROOKS D G CRAMP 1305 system that we are developing for acute chest pain probabilities were very polarised when we applied Bayes's theorem to 25 loosely related indicants. We have now reduced this number to 12 without loss of diagnostic performance, with less violation of the independence assumption, and with better calibration of the resulting probabilities. Secondly, the results of the trial in mode B hospitals reveal some important points. Most strikingly, there was no learning effect at all in the six month baseline period, despite the fact that the junior doctors in this group were all in "training" grades, and most were in "teaching" hospitals: this raises serious questions about the postgraduate education of junior staff. There also appeared to be no learning effect in the forms alone group, although their diagnostic accuracy was some 100/o higher than during the baseline period, presumably because of the "checklist effect" combined with more diligent recording of diagnosis during the test period. Surprisingly, the graph also showed no evidence of learning in the computer group, whose performance started at a high level but remained nearly static over the six months. However, during the six month "forms and feedback" trial period diagnostic accuracy did rise from the forms alone level to the same as that during the computer period, implying that the computer itself acted as an aid to performance in the early months but later on was effective only by enforcing the discipline of form filling and by providing feedback. While help to the new doctor in his first few months is undoubtedly useful to patients, it may be that by expropriating his diagnostic capabilities the computer allows the doctor to perform better while learning less. Were any data collected about the doctors' performance after the end of the study that could confirm this theory? Finally, especially in view of Dr Spiegelhalter's postscript on trial design in such studies, it would be interesting to hear comments on whether consent should be sought for trials of computer decision aids and, if so, whose? If we are allocating the doctors to control or intervention groups should they be informed of the likely performance of the computer and asked for their consent, or is it the patients (whose treatment may be altered if their doctor is in a trial) who should be consulted? JEREMY WYArr PETER EMERSON NICOLA CRICHTON Department of Chemical Pathology and Human Metabolism, Westminster Hospital, Royal Free Hospital and School of Medicine, London SWIP 2AP London NW3 2QG 1 AndersonJG, Jay SJ, SchweerHM, AndersonMM. Whydoctors don't use computers: some empirical findings. J R Soc Mcd 1986;79:142-4. SIR,-Dr I D Adams and colleagues showed that 2 Young DW. What makes doctors use computers?: discussion initial diagnostic accuracy improved from 45-6% paper.J RSocMed 1984;77:663-7. 3 Young DW. A survey of decision aids for clinicians. Br Med J during the baseline period to 65-3% during the test 1982;258:1332-6. SIR,-We are also working on computer aided medical decision making and were pleased to see the encouraging results of the multicentre trial of the Leeds abdominal pain system (Dr I D Adams and others, 27 September, p 800). We would, however, like to make some comments about the methods used and the results obtained. Firstly, we are a little concerned about the use of the independent Bayes technique, with its assumption that all indicants are unrelated, for probability calculation with large sets of data. From the full report of the study (DHSS research report, 1986) it appears that over 40 symptoms and signs were used in the probability calculation, including WILLIAM TARNow-MoRDI several that are closely associated such as "previous surgery" and "abdominal scar." In the case of a period. The authors accept that not all of the improvement observed was due to the computer feedback but that the computer "created a climate in which the inexperienced doctor was stimulated and motivated towards doing the work correctly." Fig 3 of the study shows that about 500/o of the improvement in initial diagnostic accuracy using the computer based system related to the act of filling in forms. If a full clinical history is taken the mere transcription of these facts on to a computer form would not be expected to increase initial diagnostic accuracy. It therefore follows that the initial collection of data before the introduction of the computer system was inadequate and incomplete. At the completion ofmedical trainiing all medical students should be able to take a full history in relation to acute abdominal pain. In my experience this is not done by the average house surgeon. Whether this is due to ignorance or the heavy