646

rapidly increasing number of deaths attributable to hypeitension, decade by decade.

Department of Epidemiology,St. Mary’s Hospital Medical School

London W2 1PG. HUGH TUNSTALL PEDOE

TERMINOLOGY IN BILIARY RADIOLOGY

SIR,-I fully accept the arguments of Dr Bertrand andhis colleagues (Aug. 24, p. 471) about the illogicality ofusing the two separate terms,

"

cholecystography " and" cholangiography ". In an attempt at greater accuracysome workers have even employed the ponderous term" cholecystangiography ".While agreeing with most of the terms suggested by

your correspondents, I do not, however, consider " bili-graphy " to be ideal. It is relatively short, by the standardsof medical jargon, which is greatly to its advantage, butit is a bastard production of Latin and Greek roots of thetype that philologists frown on.A member of my company seems to have originated the

term " cholegraphy ", which we have made some use of inthe past few years. It is as short as " biligraphy ", it is

surely as self-explanatory, and,, being derived from twoGreek root-,. is Hnfmistifa11v unexcentionable.

Schering Chemicals Limited,The Brow, Burgess Hill,

Sussex RH15 9NE. P. BYE.

HÆMOPHILIA CARRIERS

SIR,;-Dr Prentice and Dr Forbes (Aug. 17, p. 403)emphasised that the evaluation of methods for identifyingfemale carriers of haemophilia must ultimately be based onresults of prospective studies. No such studies have yetbeen reported with the method of Zimmerman et al.,1which compares factor vm antigen and factor vm activity,but the studies of Dr Prentice and Dr Forbes as well as ourown indicate that the predictive value may be less than thatreported by Bennett and Ratnoff.2 Since 1958 we haveclassified potential carriers as carriers or non-carriers byfactor vm activity tests alone, using repeated determinationson several occasions to eliminate errors due to fluctuationin factor vam level. In 1973 we investigated the progeny of88 of those potential carriers who had not borne a boy bythe time of her investigation.Of the 88 potential carriers, 52 had been identified as

carriers and 36 as non-carriers. During the study period(1958-72) the presumed carriers had borne 14 males, 8healthy and 6 with haemophilia A, while the presumednon-carriers had borne 9 males, all healthy:

Potential carriers

Classified as Classified asChildren carriers: 52 non-carriers: 36

MaleHealthy 8 9

Hæmophilic 6 0

Female 5 4

Despite what has been claimed 3 the method of repeatedfactor-viii determinations works well in practice. In our

hands, determination of the antigen/activity ratio does notseem to be a superior method. Combined repeated deter-minations of both activity and antigen on several occasionsmnnlrl nmhaMv he the tnnst reliable procedure

Coagulation Laboratory,Allmänna Sjukhuset,

21401 Malmö, Sweden.

I. M. NILSSONL. HOLMBERG.

1. Zimmerman, T. S., Ratnoff, O. D., Littell, A. S. J. clin. Invest.1971, 50, 255.

2. Bennett, B., Ratnoff, O. D. New Engl. J. Med. 1973, 288, 342.3. Veltkamp, J. J., Drion, E. F., Loeliger, E. A. Thromb. Diath.

hœmorrh. 1968, 19, 401.

LYMPHOCYTE TRANSFORMATION AND ORAL

CONTRACEPTIVES

SIR,-Dr Barnes and colleagues (May 11, p. 899) pre-sented evidence indicating that phytohsmagglutinin(P.H.A.)-induced blastogenesis of lymphocytes was de-

pressed in women taking oral contraceptives. We shouldlike to report here that we have obtained similar indicationsin patients receiving oestrogen and progesterone substitu-

MITOTIC INDICES IN CULTURED LYMPHOCYTES OF PATIENTS ONŒSTROGEN T’RRVAPV

tion therapy for primary ovarian failures. These patientswere receiving conjugated oestrogens (03-125 mg. perday) or conjugated oestrogens plus medroxyprogesteroneacetate (10 mg. per day). Using the standard lymphocyte-culture technique we observed in 6 patients a decrease inthe mitotic index. In the controls the mean mitotic indexwas 1053103 (s.E.)%, whereas, in the study subjects itwas 5-67:0-90 (s.E.)% (see accompanying table).The batch of phytohæmagglutinin (P.H.A.) used had an

unusually potent mitogenicity, which accounted for therelatively high mitotic index in the controls. The aboveevidence, therefore, further supports the findings of

-1

Department of Pediatrics,College of Physicians and Surgeons,

Columbia University,New York, New York 10032, U.S.A.

AKIRA MORISHIMARICHARD T. HENRICH.

ORAL CONTRACEPTIVES, ALLERGY,PREGNANCY, AND DEPRESSION

SIR; One of the recognised hazards of publishing re-search results in the form of a monograph is that otherworkers tend to rely on summaries and reviews. DrFalliers (Aug. 31, p. 515) seems to be in this category.Had he consulted the original 1 he would have found muchevidence to support his hypothesis that oral contraceptivesmodify allergic responses. A possible relationship to nasalcatarrh, hay-fever, and allergic rhinitis is discussed in

chapter 8, while in chapter 10 more convincing evidence ispresented of a relationship to atopic eczema and eczema dueto external agents, photosensitivity, neurodermatitis, andthe non-specific erythemas.Dr Robertson-Rintoul’s view (Aug. 31, p. 515) that

oral contraceptives may be teratogenic is not supported bythe data in our report. The outcome of pregnancy wasdetermined in 96 women who conceived accidentally wlulethey were still using the pill (chapter 11). Their experienceprovides no evidence that their pregnancies were in anyway affected by the continued ingestion of oral contracep-tives during the early weeks after conception. There is no

justification for Dr Robertson-Rintoul’s plea that all thesewomen should be offered therapeutic abortion.Our report concludes that depression is probably an

1. Royal College of General Practitioners. Oral Contraceptives andHealth. London, 1974.

647

uncommon result of pill usage, an observation that agreeswith several other well-controlled studies.2-5 The reportsof depression were 30% higher in the takers than in thecontrols, but since a considerable degree of biased over-reporting must be expected in takers, the pharmacologicaleffect of the pill is likely to be substantially smaller. Thismeans that in any group of oral-contraceptive users whobecome depressed, the pill can be considered the cause oftheir depression in less than 25% of the women.These remarks are prompted by the letter from Dr Adams

and his colleagues (Aug. 31, p. 516) reporting that depressedpill users who have an absolute deficiency of vitamin B6respond to the administration of pyridoxine hydrochloride.In their placebo-controlled trial, the depression of 10 out ofthe total of 39 subjects (25%) improved only with thepyridoxine treatment.The implication that it is only this proportion of de-

pressed pill users whose depression is pharmacologicallyassociated with oral contraceptives accords well with ourown observations, bearing in mind that the subjects in thecontrolled trial were specially selected because their depres-sion was thought to be due to the pill. 6

If the findings of Dr Adams’ team can be confirmed on awider scale, it is possible that they can provide the basisfor management of depressed pill users which avoids thearbitrary discontinuation of the pill-an action whichexposes the women to a greatly increased risk of an un-planned pregnancy (chapter 12 1) and has no scientificrationale in at least 75% of instances.

R.C.G.P. Oral Contraception Study,8 Barlow Moor Road,Manchester M20 0TR. CLIFFORD R. KAY.

PREDICTIVE VALUE OFLABORATORY TESTS

SIR,--In their discussion of the value of new laboratorytests in diagnosis and treatment, Professor Holland andProfessor Whitehead (Aug. 17, p. 391) mention the pre-dictive value of a test-that is, the proportion of truepositive results in relation to the total number of positives(both true and false) given by the test. While this value isindeed determined in the strictest sense by the sensitivityand specificity of a test one must consider for practicalpurposes the prevalence of the disease or condition beinglooked for by the test.

If we administer a screening or diagnostic test with asensitivity of 90% and a specificity of 90% to a group of1000 persons where the prevalence of a condition or diseaseis 10% we will see the following:

Disease status

Diseased Not diseasedPositive 90 90 180 total positivesNegative 10 810

Totals 100 900

Under these circumstances the predictive value is 50%as 90 of 180 positives are true positives. By lowering onlythe prevalence of the disease, however, to 1% a differentpicture emerges:

Disease status

Dzseased Not diseasedPositive 9 99 108 total positivesNegative 1 891

Totals 10 990

In this instance (note the sensitivity is still 90% and the

2. Kutner, S. J., Brown, W. L. J. nerv. ment. Dis. 1972, 155, 163.3. Kutner, S. J., Brown, W. L. ibid. p. 153.4. Goldzieher, J. W., Moses, L. E., Averkin, E., Scheel, C., Tabler,

B. Z. Am. J. Obstet. Gynec. 1971, 111, 1013.5. Cullberg, J. Acta psychiat. scand. 1972, 236, suppl.6. Adams, P. W., Rose, D. P., Folkard, J., Wynn, V., Seed, M.

Strong, R. Lancet, 1973, i, 897.

specificity is still 90%) the predictive value is only 8-3%as only 9 of the 108 positives are true positives.Thus the prevalence of a disease or condition must be

considered as important as sensitivity and specificity indetermining the value or validity of a screening or diagnosticprocedure.Department of Public Health and

Epidemiology,University of Alabama in

Birmingham Medical Center,Birmingham, Alabama 35294,

U.S.A. HERMAN F. LEHMAN.

MEDICAL NEMESIS

SIR Professor Discombe (Sept. 7, p. 584) says Ivan Illich’s language is obscure, and so it is; but I think oneshould remember that Illich was brought up from birth tospeak four languages, and, although now fluent in thoseand in others, he admits that none is his easy native tongue.A second element to the obscurity is that his training hasbeen in crystallography and theology: scientific medicalmen and crystallographic theologians make uneasy bed-fellows. A third and probably the most important elementin Illich’s " obscurity " will often escape and perhaps noteven appeal to most scientific doctors; and it is illustratedby what Professor Discombe quotes with disapproval:" The sickening technical and non-technical consequencesof the institutionalisation of medicine coalesce to generate .

a new kind of suffering—anæsthetised and solitary survivalin a world-wide hospital ward." He says it has no meaningexcept perhaps " I don’t like doctors ". It is, in fact, thelanguage of the seer and the poet; a groping seer perhaps,and a clumsy poet-for he is seeing and singing about analien topic in a strange land-but it is still the languageneeded to plumb depths beyond the reach of doctors, thelanguage of a territory separate from that of medicine, andmore important, as its language has done much more thanthat of medicine to shape our cultures and our civilisations,at least if one takes a millennial view. Illich is most at homewith myths; and myths are more important than medicine.As to the notion that Illich does not like doctors: it

would, I am sure, not be entertained for a moment by anydoctor who has met him. He is a warm, unassuming person,as ready to listen as to talk, delighted to find himself inagreement with a medical man, and with a sparkling senseof humour that alas finds less scope in the pages of hisbooks than in his conversation. Dislike of doctors wouldbe quite foreign to him. Nor does he want to see usabolished: only put in our place, like everyone else. He

certainly does not wish, as Professor Discombe suggests,that people should experience pestilence, battle, murder,and sudden death, and thank God for the experience. Andafter all, they would be hard put to it to thank Him forexperience of the last two.Having read the whole of the manuscript of Medical

Nemesis, the Ivan Illich book that is to appear shortly and afew sections of which were the basis for the publishedlecture to which Professor Discombe refers, I found myselfhalf-reluctantly, and, despite disagreement over details,accepting nearly all of the central Illichian thesis; and Ithink critics should stay their hands until the book appears.A few of Illich’s medical details may, as Professor Discombesays, be moonshine; but if the professor or I were toventure into the field of theology, would there not be afew small mistakes ? To take a broad tack, it is not moon-shine that, during a period in which the Chinese barefootdoctors have apparently performed miracles, Westernmedicine has moved into crisis: the expectation of lifein various Western countries, especially for males, is staticor falling; the U.S.A., in which that trend is very marked,has pari passu with it been sucking in an incredibly large