delaying their first pregnancy or who have decided not to have any more children.' In tackling the potentially embarrassing discussion of sexual matters that might be necessary in considering choices in contraception the greater anonymity of the clinic is useful for some women who are reluctant to see their family doctor. Women attending clinics also explain the importance to them of being sure that they will be seen by a woman doctor.' For women who are not registered with a local general practitioner the self referring health authority clinics can be their only source of contraceptive advice and supplies. In many inner city areas a substantial proportion of the women attending clinics are not registered with a general practitioner. The currently available choice for women to seek their contraceptive health care from either a general practitioner or a district health authority run service should not be lost when so many women "vote with their feet" and attend clinics. The recent publication of further guidance from the Department of Health on contracts for health services acknowledges that for self referring clinics, where the guarantee of choice for patients is the objective, there is no one between the patient and the provider with whom the district health authority can discuss contracts.5 "Regional health authorities will be expected to ensure that relevant units are funded in a way that allows patients to self-refer." This acknowledgement provides a platform to make the case for continued funding for district health authority as well as general practitioner run family planning services.

twice and generate four report forms. I may have made as many as 10 computer entries, the exact number depending on my assessment of the clinical relevance of each test. Another doctor might disagree and record them differently. Which of these numbers am I to offer to my family practitioner committee? This question may seem frivolous but it is fundamental. A practice which is simply counting attendances at the laboratory will seem to have a lower referral rate than one which is counting forms, and both will seem lower than those who are counting the detailed results of all reports received. Whether it is worth collecting this information at all is a matter for debate. One thing, however, is certain: to leave individual doctors or practices to decide what will be recorded, and how, will produce a pool of worthless data. rhis will waste vast amounts of computer time and staff time, commodities that the NHS can ill afford to squander. It may be tactless to say so, but this is precisely the sort of problem a pilot study or two could have solved.

CONAMORE SMITH

SIR,-In their second letter' Dr Joan Slack and colleagues have corrected an error in their first letter2 in the calculation of the probability of a member of the northern European population being a carrier for cystic fibrosis-more precisely, that given a negative result in the gene deletion AF508 "test." Several issues remain, however. Firstly, surely the title of table I should refer to the chances of being a carrier before testing and among those without gene deletion AF508. Secondly, two of the prior probabilities in this table are still incorrect. By our calculations the prior probability of being a carrier in those with a first cousin affected is about 1 in 4, not 1 in 8; with an uncle or aunt affected the chance is about 1 in 3, not 1 in 4. For sensitivities of 70% and 80% the respective probabilities of being a carrier after a negative test result are 1 in 10 and 1 in 15 for those with a first cousin affected and 1 in 7 and 1 in I1 for those with an uncle or aunt affected. More generally, all of the calculations concerning relatives of an affected person are strictly valid only if that person's genotype is unknown. For example, if the affected person is known to have gene deletion AF508 then all of the risks in table I would require modification (apart from the first row, which refers to the general population). Moreover, we believe that the deletion test should, and will, be offered to relatives of affected people in any case; the real issue is that of population screening, for which the pertinent information is contained in the table below:

Raymede Health Centre, London W1O SSH

JOHN GUILLEBAUD Margaret Pyke Centre, London MC: 1IV 5TI X' SAM ROWLANDS

Bedfordshire SG 18 OPX 1 Jenkins S. Screening and the 1990 contract. BrMedJ7 1990;300: 825-6. (31 March.) 2 Department of Health Statistics and Management Information Division. Family planning clinic services 1977-198718. London: DoH, 1989. (SMI 2B.) 3 Davis T. Family planning. House of Commons Official Report (Hansard) 1989 November 1;159:cols 23-5. (No 165.) 4 Snowden R. Consumer choices infamtlvP planning. London: Family Planning Association, 1985.

5 NHS Management Executive. Contracts for health services: operating contracts. London: Department of Health, 1990.

(EL(90)MB/24.)

SIR,-As Dr S Jenkins explains,' general practitioners must use computers to collect information about the number of radiographs and laboratory tests that they request. At first glance this seems a simple matter, readily delegated to an appropriately trained secretary. Closer examination discloses several difficulties. If a woman with a history of breast cancer presents with a painful arm I may send her for radiography of her arm, chest, and spine. She attends the radiography department once. I complete one request form and receive one report. When I come to record the results, however, my computer's obsessional neurosis requires me to make three entries, one for each part of the body examined by radiography. Similarly, if I request tests for another patient for blood count, thyroid function, and serum concentrations of urea and electrolytes, the patient attends the laboratory once. I complete three forms and get three back. If I am screening simply to exclude an abnormality I may be content to record "Full blood count-normal" on my computer. If I am monitoring the progress of a disease, however, I may wish to enter the exact figures for one or more of the individual components of those tests. The machine counts each entry as a separate test. My two hypothetical patients attend hospital

1198

not routinely testing their partners) among the 3 5'S, with a positive test result the chance of the conceptus being affected is 1 in 80 before the partner is tested; for the remaining 96-5% the risk will be reduced to about 1 in 5100. Whether such procedures are worth while is debatable at present, considering that the calculations relate to detection of a single mutation (albeit the commonest and possibly most severe) and that many other mutations are currently being described. T J PETERS G OWEN R G NEWCOMBE

Departments of Mtledical Computing and Statistics and Child Health (Cy,stic Fibrosis Unit), University of WXales College of Medicine, Cardiff CF4 4XN I Slack J, Houlston RS, Marteau T. Identification of the cystic fibrosis gene. BrMed 7 1990;300:1015. (14 April.) 2 Slack J, Houlston RS, Marteau T. Identification of the cystic fibrosis gene. BrMed j 1990;300:812. (24 March.)

ROBERT ROUSE ColwNxn Bay, Clw\yd LL29 5AE

Venous ulcers

1 Jenkins S. Organisation of screening: a practical vicw. BrMfedJ 1990;300:1050-2. (21 April.

Identification of the cystic fibrosis gene

Chance of conceptus being affected according to results in parents on population screening for gene deletion AF508 Percentage of Chance of couples in the conceptus bcing (full} ) screened affected population Both unscreened Both negative One positive, one negative Both positive

I in 1600 1 in 17000 1 in 260 1 in 4

93-1

658 0 1

The central question is then whether the gain represented by the additional discrimination is worth while. If only one partner is screened (for example, by testing women at antenatal clinics but

SIR, -We think that several points should be made regarding Dr Stanley Allen's leading article on venous ulcers.' We agree that all general practitioners should be able to recognise the condition early but disagree with Dr Allen that they should be the principal organisers of care for patients with venous ulcers. He admits that most of these patients can be managed in the community by appropriate nursing methods, and we think that a community based nurse specialist can provide the best care. Such a nurse can educate district nurses and foster a high standard of care throughout a whole health district. Because she or he is dealing exclusively with patients with leg ulcers she or he can aspire to a higher standard than could overworked and sometimes disinterested general practitioners, who may have only one or two patients with chronic leg ulcers at any one time. Dr Allen also states that admission should be considered only if an ulcer does not respond to adequate compression or is accompanied by severe pain, suggesting an arterial element. In elderly people who suffer with venous leg ulceration concomitant arterial disease is extremely common, frequently painless, and, unfortunately, often missed. As well as preventing healing, compression and elevation (the mainstay of treatment of venous ulcers) can be harmful and lead to necrosis. Arterial disease can be screened for cheaply and easily by using a hand held Doppler ultrasound machine to assess the foot pulses. Our nurse specialist is well trained in using this simple device, and it is used as part of the initial assessment on all new patients with leg ulcers. Another advantage of such a nurse specialist is that she or he can bridge the gap between community and hospital care. Our nurse specialist attends the vascular clinic weekly, and joint discussions occur about the patients with difficult or intractable ulcers. We also -desire that hospital admission for treatment of leg ulcers should be kept to a minimum and find that this close liaison between community care and the hospital outpatient clinic provides the best method of ensuring that this is so. G STANSBY S ETTEDGI G HAMILTON

Royal Free Hospital, ILondon NW3 2QG

I Allcn S. Venous ulcers. BrMedj 1990;300:826-7. (31 M1arch.)

SIR,-Though we agree with Dr Stanley Allen that patients with venous ulcers are best treated with compression bandaging and that most patients

BMJ VOLUME 300

5 MAY 1990

Identification of the cystic fibrosis gene.

delaying their first pregnancy or who have decided not to have any more children.' In tackling the potentially embarrassing discussion of sexual matte...
293KB Sizes 0 Downloads 0 Views