the colour and a tell tale extension of pigment at one edge. As the checklist acknowledges, change in behaviour is the most important fact to emphasise in a public education campaign. But some patients are oblivious to change,' I and their melanoma is diagnosed incidentally by someone else. It is thus important that doctors, paramedics, and the public are exposed to as much visual material depicting melanomas as possible, either on television or in poster form. Those doctors who see patients with malignant melanoma should show the lesions to as many colleagues as possible.

Analysis ofyellow card reports of adverse drug reactions by number of times each doctor reported during 1972-80

ANTHONY DU VIVIER ELISABETH M HIGGINS

doctors using the scheme only once, but 42% came from doctors making six or more reports (table). Furthermore, six doctors reported on over 100 occasions, and they contributed nearly 1-5% of the total reports during 1972-80. Similar analyses of more recent data would not seem to be possible as the minister of health stated in 1989 that "we do not record the numbers of individual doctors and dentists who report adverse drug reactions to the CSM and this information would be provided only at disproportionate cost."3 The only comparable analysis by another national drug regulatory authority of frequency of reports of adverse drug reactions by individual doctors was supplied to me by Dr R Meyboom of The Netherlands Centre for Monitoring Adverse Drug Reactions for the year 1987. Only 2-16% of doctors on the Dutch medical register reported adverse reactions. About half of those reports came from doctors reporting only once and 7-7% came from doctors reporting on six or more occasions. The Committee on Safety of Medicines is keen to increase the value of the spontaneous adverse reaction reporting system. To do this it needs to encourage more widespread use of the system among doctors rather than to receive more reports from the same enthusiasts.

King's College Hospital, London SE5 9RS 1 MacKie RM. Clinical recognition of early invasive malignant melanoma. BM3' 1990;301:1005-6. (3 November.) 2 Keefe M, Dick DC, Wakeel RA. A study of the predictive value of the 7 point checklist in distinguishing benign pigmented lesions from melanoma. Clin Exp Dermatol 1990;15: 167-71. 3 Du Vivier A. Cutaneous malignant melanoma: a potentially curable disease. BrJ Hosp Med 1989;41:357-63. 4 Du Vivier AWP, Williams HC, Brett JV, Higgins EM. How do melanomas present and how does this correlate with the 7 point checklist? BrJ7 Dermatol 1990;123(suppl 37):39-40. 5 Monk BE, Clement M, Pembroke AC, du Vivier A. The incidental malignant melanoma. BM3 1983;287:485-6.

Aerobic work capacity in chronic fatigue syndrome SIR,-Dr Marshall S Riley and colleagues noted that the changes in indicators of aerobic work capacity in patients with the chronic fatigue syndrome resembled those observed in deconditioned subjects.' The chronic fatigue syndrome often develops after acute infectious disease, and its aetiology has therefore been related to infective agents. Over 120 years ago DaCosta described acute infection as one of the stressors that seemed to start a syndrome characterised by easy fatigability, weakness, and many symptoms referring to the cardiorespiratory and the gastrointestinal systems.2 Since then this syndrome has been described many times and under many names (for example, DaCosta's syndrome, the effort syndrome, neurocirculatory asthenia, and the mitral valve prolapse syndrome). DaCosta and many other investigators concluded that this syndrome was an unspecific reaction to overwhelming physical or psychlc stress, and low physical work capacity was regarded as a predisposing factor. When studying the aetiology of the chronic fatigue syndrome it would be worth referring to the many published reports on DaCosta's syndrome, even though they are published mainly by cardiologically oriented investigators. MATTI MANTYSAARI

Kuopio University Hospital, SF-70210 Kuopio, Finland 1 Riley MS, O'Brien CJ, McCluskey DR, Bell NP, Nicholls DP. Aerobic work capacity in patients with chronic fatigue syndrome. BMJ 1990;301:953-6. (27 October.) 2 DaCosta JM. On irritable heart: a clinical study of a form of functional cardiac disorder and its consequences. Aml Med Sci

1871;121:2-53.

The yellow card: mark II SIR,-Dr D H Lawson's editorial did not draw attention to the extremes of use or non-use of the yellow card system by doctors in the United Kingdom.' Speirs et al showed that only 16% of doctors working in the United Kingdom during 1972-80 reported adverse drug reactions to the Committee on Safety of Medicines using the yellow card system.2 Almost 20% of the reports came from 50

be readily identified by a straightforward questionnaire about symptoms.7 P J WHORWELL

No of doctors reporting (% of No of times doctor doctors working in NHS at any time during 1972-80) reported

No (%) of reports received

1 2 3 4 5 -_6

10 690 (8-6) 3 701 1 833 1011 694 1 820 (1-47)

10 690 (19-9) 7 402 (13-8) 5 499(10-2) 4044 (75) 3 470 (6-5) 22 580 (42-0)

Total

19 749(16-0)

53 685

J P GRIFFIN Association of the British Pharmaceutical Industry, London SWIA 2DY

1 Lawson DH. The yellow card: mark II. BMJ 1990;301:1234. (1 December.) 2 Speirs CJ, Griffin JP, Weber JCP, Bott MG, Twomey CCS. Demography of the UK adverse reactions register of spontaneous reports. Health Trends 1984;16:49-52. 3 Mellor D. Parliamentary written answer. House of Commons Official Report (Hansard) 1989 January 25;145:col 547. (No 35.)

University Hospital of South Manchester, Manchester M20 8LR 1 David A, Pelosi A, McDonald E, et al. Tired, weak, or iri need of rest. Fatigue among general practice attenders. BMJ 1990; 301:1199-202. (24 November.) 2 Whorwell PJ, McCallum M, Creed FH, Roberts CT. Non colonic features of irritable bowel syndrome. Gut 1986;27: 37-40. 3 Maxton DG, Morris JA, Whorwell PJ. Ranking of symptoms by patients with irritable bowel syndrome. BMJ 1989;299: 1138-9. 4 Maxton DG, Whorwell PJ. More accurate diagnosis of irritable bowel syndrome by the use of non-colonic symptomatology. Gut 1990;31:A1167. 5 Maxton DG, Whorwell PJ. More accurate diagnosis of irritable bowel syndome by the use of non-colonic symptomatology. Gut (in press.) 6 Thompson WG, Heaton KW. Functional bowel disorders in apparently healthy people. Gastroenterology 1980;79:283-8. 7 Manning AP, Thompson WG, Heaton KW, Morris AF. Towards positive diagnosis of the irritable bowel syndrome. BMJ 1978; ii:653-4.

Prediction of hip fracture in elderly women SIR,-Dr Albert M Van Hemerts' incorrectly states the sensitivity and specificity of the blood band ultrasonic attenuation (BUA) index in predicting hip fracture in our study.2 Our data did not allow such calculations to be made as no account had been taken of the many patients who had died (more than 300) before a hip fracture may have been sustained. Also the data were not presented in an ideal manner for such a calculation to be undertaken. Another study showed that the BUA index had a sensitivity of 81% and a specificity of 94% to discriminate between control women and women with osteoporotic fractures. The potential of ultrasonography to predict hip fracture in a normal population is considerably greater than it is in a group of women at high risk such as those we described (5 2% had a fracture in the two years). The BUA index and the Clifton assessment procedures for the elderly were able to predict those women at highest risk of sustaining

hip fracture. COLIN G MILLER

Norwich Eaton, Egham TW20 9NW RICHARD W PORTER Doncaster Royal Infirmary, Doncaster DN2 5LT

Fatigue among general practice attenders SIR, -Dr Anthony David and colleagues report a prevalence of fatigue of 10 5% but did not, as far as we can tell, record any gastrointestinal symptoms. ' We recently found that fatigue seemed to be strongly associated with the irritable bowel syndrome. It occurs in up to 96% of hospital outpatients with the disorder24 irrespective of the presence of psychopathology and also has diagnostic potential in helping to distinguish irritable bowel syndrome from other gastrointestinal diseases.5 It is not known whether fatigue is common in patients with the irritable bowel syndrome in the community, but even if it were less common than in patients attending gastroenterology clinics, the prevalence of the syndrome in the general population is so high (15%)6 that I would still expect to find many subjects with fatigue associated with the syndrome. It is therefore tempting to speculate that the syndrome may be accounting for a substantial number of cases of fatigue in the study by Dr David and colleagues. They state that they are assessing this cohort of patients further. We would strongly urge them to look for the irritable bowel syndrome, particularly as there is now good evidence that this disorder can

I Van Hemert AM. Prediction of hip fracture in elderly women.

BMJ 1990;301:1100. (10 November.) 2 Porter RW, Miller CG, Grainger D, Palmer SB. Prediction of hip fracture in elderly women: a prospective study. BMJ

1990;301:638-41. (29 September.) 3 McClockey EV, Murray SA, Miller C. Broadband ultrasound attentuation in the os calcis: relationship to bone mineral at

other sites. Clin Sci 1990;78:227-33.

HIV infection in women SIR,-Dr Stephen Norman and colleagues state that the question of pregnancy in the uninfected spouse of a man infected with HIV has not been examined.' This position is common to many partners of haemophiliac patients world wide and has been the subject of several studies since AIDS was first reported in haemophiliac patients in 1982. In the United Kingdom repeated advice about contraception has been issued by the Haemophilia Society since early 1985.2 The counselling of couples wanting to have children has also been described.3 We have reported the management of 12 children negative for HIV antibodies conceived when their fathers were positive for these antibodies (E Goldman et al, sixth world congress on AIDS, Montreal, 1989). Many haemophiliac patients seroconvert at a young age (in our cohort the median age at seroconversion was 24 years, range

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2-774), and thus couples who want to have children will continue to present. If a couple decide to have a child after they have been informed of the risks we advise the man to have a sperm count to rule out oligospermia and issue ovulation kits with advice to have unprotected intercourse only at the time of ovulation. As soon as pregnancy is confirmed the woman is referred to the consultant obstetrician in our hospital to register for antenatal care. We suggest a further HIV test at three months' gestation when termination might be an option, and we stress the need to use condoms throughout the pregnancy. The mother and baby are tested postnatally, and provided that the mother remains uninfected with HIV and condoms are used we advise that breast feeding is safe. Despite being aware of the risks couples will continue to have children. We believe that information should be provided to reduce these risks as far as possible. CHRISTINE LEE RIVA MILLER ELEANOR GOLDMAN Royal Free Hospital, London NW3 2QG 1 Norman S, Studd J, Johnson M. HIV infection in women. BMJ 1990;301:1231-2. (1 December.) 2 Haemophilia Society. Haemofact AIDS. No 7. London: Haemophilia Society, 1985. 3 Miller R, Bor R. Counselling for HIV screening in women. In: Studd J, ed. Progress in obstetrics and gynaecology. Vol 8. London: Churchill Livingstone, 1990:175-90. 4 Lee CA, Phillips A, Elford J, et al. The natural history of human immunodeficiency virus infection in a haemophiliac cohort. Br7 Haematol 1989;73:228-34.

HIV and surgeons SIR,-Messrs David Hamblen and Geoffrey Newton describe the risk of HIV infection among orthopaedic surgeons.' We think that it is time to draw attention to the burden of surgeons and other medical staff (especially midwives) working in places where a fifth or more of all patients coming to the operating room or delivery ward are positive for HIV antibodies. We have used the formula 1 -(1 - fp)f to calculate the risk of HIV infection, where f is the prevalence of HIV, p the risk of transmission, and n the number of injuries (R A Coutinho, personal communication). If the risk of infection with HIV is estimated at 0 5% after each injury (needlestick or instrumental) and the number of injuries is 10 a year the risk of infection with HIV is 26% over a 30 year career. We wonder how many surgeons in industrialised countries, given the sometimes difficult work circumstances, would accept this degree of risk. A DE CLERCQ

concentrations of the drug was thought to be responsible.2 A retrospective study has suggested an association between the septic complications of diverticular disease and non-steroidal anti-inflammatory drugs.' The drugs inhibit prostaglandin synthetase, and experimental evidence has suggested that a decrease in mucosal prostaglandins may, by abolishing a "cytoprotective" effect, compromise intestinal integrity resulting in an increased susceptibility to transmucosal migration of luminal toxins.4 During 12 months we have treated three elderly constipated patients who developed stercoraceous perforations of the sigmoid colon while taking indomethacin, naproxen, and a sustained release preparation of ketoprofen. All three cases were reported to the Committee on Safety of Medicines. Although the development of these lesions was undoubtedly multifactorial and constipation the prime factor, the suspicion of an association with non-steroidal anti-inflammatory drugs seems justified. Impairment of mucosal resistance to the trauma induced by faecal stasis in patients taking these drugs could be a contributory factor. Another study has shown that 26% of patients admitted with small and large bowel perforations and haemorrhage were taking non-steroidal antiinflammatory drugs.' There are fewer than 50 reported cases of stercoraceous perforation, and in those in which drugs are implicated it is because of their constipating side effects.67 Surprisingly, non-steroidal anti-inflammatory drugs are rarely mentioned, and a causal association has never been considered. This may be explained by a failure to document that patients were taking these drugs, particularly if an aetiological role is not considered. Although the potential upper gastrointestinal effects of non-steroidal anti-inflammatory drugs have been widely emphasised, more progress is needed to define the incidence of and those patients at greatest risk from adverse lower gastrointestinal reactions. J HOLLINGWORTH

Selly Oak Hospital, Birmingham B29 6JD 1 Clements D, Williams GT, Rhodes J. Colitis associated with

ibuprofen. BMJ 1990;301:987. (27 October.) 2 Day TK. Intestinal perforation associated with osmotic slow-

release indomethacin capsules. BMJ 1983;287:167 1. 3 Corder A. Steroids, non-steroidal anti-inflammatory drugs, and serious septic complications of diverticular disease. BMJ 1987;295: 1238. 4 Robert A. An intestinal disease produced experimentally by prostaglandin deficiency. Gastroenterology 1975;69: 1045-7. 5 Langman MJS, Morgan L, Worral A. Use of anti-inflammatory drugs by patients admitted with small or large bowel perforation and haemorrhage. BMJ 1985;290:347-9. 6 Stringer MD, Greenfield S, McIrvine AJ. Stercoral perforation of the colon following postoperative analgesia. J7 R Soc Med 1987;80: 115-6. 7 Cass AJ. Stercoral perforation: case of drug induced impaction.

BMJ 1978;ii:932-3.

L OEYEN

Analysing ordered categorical data

BP 934 Kigali, Rwanda 1 Hamblen D, Newton G. HIV and surgeons. BMJf 1990;301: 1216-7. (24 November.)

Colitis associated with ibuprofen SIR,-The report by Dr D Clements and colleagues of colitis associated with ibuprofen' is further evidence that non-steroidal anti-inflammatory drugs may cause ileocolonic damage. The role of these drugs in colonic disease remains poorly defined and may be underestimated, reports being uncommon, often anecdotal, and difficult to evaluate. These drugs can cause conditions other than colitis. The osmotic sustained release preparation of indomethacin, Osmosin, was withdrawn after reports of ileocolonic perforation. Exposure of the lower bowel to particularly high BMJ

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SIR,-Dr Anthony P Morton and Professor Annette J Dobson write that when ordered data are treated as if they were continuous the differences between the means and medians of the two samples are meaningless point estimates.' They state that using ct and b obviates this problem but do not mention that these statistics pose severe interpretational problems of their own. Consider the results from two trials, each with 16 patients and two treatments, A and B. The patients are measured on a 10 point scale. The results from the two trials have been sorted within groups and are as follows: TrialI A:44445555 B:5 5556666

TrialII A:12345678 B: 2 3456789

The difference between the means of the two treatment groups in each case is 1, as is the difference between the medians. Thus if the data are treated as continuous the results from both trials are consistent with the theory that the effect of B compared with A is to improve results by one category. Of course the confidence limits, by virtue of the difference in variability, will be different. If 6 is calculated for the two trials, however, we get a value of 0 75 for trial I and of 0 234 for trial II. Thus b reflects scale as well as location. As patients in clinical trials cannot and should not be regarded as a random sample from a target population2 reflecting scale is an undesirable property of point estimators. It is thus incorrect to say that using i and 6 obviates problems with ordered categorical data. STEPHEN SENN Ciba-Geigy, 4002 Basle, Switzerland 1 Morton A, Dobson A. Analysing ordered categorical data from two independent samples. BMJ 1990;301:971-3. (27 October.) 2 Senn S, Auclair P. The graphical representation of clinical trial with particular reference to measurements over time. Stat Med 1990;9: 1287-302.

Incidence of advanced renal failure SIR,-Professor Mary G McGeown and Dr T G Feest and colleagues provided important new information on the incidence and prevalence of advanced chronic renal failure that highlights the underreferral of patients in the United Kingdom. "I Their estimate of 78 new patients per million population per year, however, may well be an underestimate of the incidence in some health districts. We recently completed a review of the renal services for the South East Thames Regional Health Authority. One of the main points considered in the review was the level of need across the region and how best the services could develop to cope with increasing demand for treatment. The region represents a wide range of demographic and social groups. Important characteristics determining variation in treatment rate among districts included the age structure, distance of residence from a renal unit, and the proportion of AfroCaribbeans. In the United States black people have been shown to have a higher incidence and prevalence of chronic renal failure than white people.3 Dr Feest and colleagues could not study AfroCaribbeans as their study population did not include a wide range of ethnic groups. They did, however, report that Asians did not seem to have a significantly different incidence of chronic renal failure from white people. In South East Thames region the annual acceptance rate of new patients in 1988-9, excluding nonresidents, was 49-3 per million, slightly below the United Kingdom average of 55-1 estimated by the European Dialysis and Transplant Association.4 The treatment rate varied considerably among districts, however, with the acceptance rate of new patients in Camberwell and west Lambeth (123-5 and 83 per million per year respectively) already being well above the incidence of 78 new patients per million estimated by Dr Feest and colleagues. The high treatment rate of new patients in these districts may be partly explained by the presence of renal units within the districts but also by districts' high proportions of Afro-Caribbeans. The 1981 census data showed that about 22% of the populations in Camberwell and west Lambeth belonged to ethnic minorities, mainly Afro-Caribbeans. This group is known to be predisposed to hypertension, non-insulin dependent diabetes mellitus, and systemic lupus erythematosus, which in turn can lead to end stage renal failure.' In addition, there are other groups-, such as the Vietnamese, who are 51

HIV infection in women.

the colour and a tell tale extension of pigment at one edge. As the checklist acknowledges, change in behaviour is the most important fact to emphasis...
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