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CHANGES IN SEXUAL BEHAVIOUR AND FEAR OFAIDS

SIR,-A high number of sexual partners is strongly associatedwith the development of the acquired immunodeficiency syndrome(AIDS) in homosexual men. We are conducting a cohort study in800 homosexual males in Vancouver. Recruitment- was donebetween November, 1982, and February, 1984, through six generalpractices which cater entirely or predominantly for homosexualmen. Volunteers completed a self-administered questionnaire at thetime of enrolment, giving demographic, historical, and lifestyleinformation. Questions about sexual practices were posed in thewidely used vernacular. A second questionnaire was administered atleast 3 months later at the first follow-up visit. The second

questionnaire asked about changes in sexual practice sinceenrolment in the study.So far we have follow-up data for 388 men. Over half reported a

decrease in the number of sexual partners (see table). Theproportion of respondents reporting no more than five partners peryear rose from 2107o to 37%. Specific sexual practices (see table) weremore likely to have decreased than increased, except for oral-genitalcontact. This is more striking for the four less popular sexualactivities than for anal intercourse.

CHANGES IN SEXUAL ACTIVITIES BETWEEN TWO QUESTIONNAIRESURVEYS ON A GROUP OF VANCOUVER HOMOSEXUALS

-

I T T

no B- , - i - ,

.

1

’Relauve frequencies of change among those who ever participated in the activity.(a)=active; (r) = receptIve,

Golubjatnikov et al2 have noted a decline in number of sexualpartners for a clinic-based homosexual population in Wisconsin.Our population, recruited through general practitioners with anenrolment rate of 95% among those asked to participate, is likely tobe fairly representative of the homosexual community. However,the mere fact of participation in an AIDS-related study might havehad an educational effect, and the observed changes may be inflated.Nevertheless, the evidence points to a decline in overall sexualactivity and also in certain specific activities, a selectivity that mightstem from differences in risk of AIDS as perceived by homosexuals.It is not clear if a decrease in sexual activity is related to the recentdecline in the incidence of AIDS.3

Vancouver Lymphadenopathy-AIDS Study Group,Departments of Health Care and Epidemiology,Family Practice, Medicine, and Pathology,

St Paul’s Hospitaland University of British Columbia,

Vancouver, Canada V6Z 1Y6

M. T. SCHECHTERE. JEFFRIESP. CONSTANCEB. DOUGLASS. FAYM. MAYNARDR. NITZB. WILLOUGHBY

W. J. BOYKOA. MACLEOD

1. Jaffe HW, Choi K, Thomas PA, et al. National case-control study of Kaposi’s sarcomaand Pneumocystis carinii pneumonia in homosexual men I. Epidemiologic results.Ann Intern Med 1983; 99: 145-51

2. Golubjatnikov R, Pfister H, Tillotson T. Homosexual promiscuity and the fear ofAIDS. Lancet 1983; ii: 681.

3 Anon. AIDS activity report Atlanta, Georgia: Center for Infectious Diseases (March12, 1984).

METHOD FAILURE PREGNANCY RATES WITH DEPO-PROVERA AND A LOCAL SUBSTITUTE

SIR,-Since 1965 the McCormick Hospital family planningprogramme, in Chiang Mai, Thailand, has been using ’Depo-Provera’ (depot medroxyprogesterone acetate or DMPA)manufactured by Upjohn, as a three-month, 150 mg, long-acting,injectable contraceptive. Because of an unavoidable change in

source of supply, in 1982 we switched to another brand of DMPA,marketed as ’Pheno-M’ by a local pharmaceutical company.Overthe subsequent 15 months our clinic staff noted an apparent excessof method failure pregnancies. In August, 1983, we withdrewpheno-M from our programme because of our clinical impressionthat excessive failures were occurring with this drug. Since Aug 14,1983, we have used only depo-provera.The data from our routine clinic surveillance system

underestimate the frequency of accidental pregnancies because ofunder-reporting, and we are undertaking a detailed follow-up studyof women who used pheno-M, to estimate more accurately themethod failure rates. However, during the period from May 1,1980, to March 31, 1984, our surveillance procedures wereunchanged; and we would not expect to observe any abrupt increaseor decrease in method failures due to alteration in case

ascertainment or reporting.In the complete clinical records of the urban family planning

clinic in Chiang Mai we found that during the 15 month period May1, 1980, to July 31, 1981, when depo-provera was used exclusivelyfor 51 358 injections (12 840 woman years of use), 18 methodfailures were observed, giving a Pearl pregnancy rate of 0 - 14 per100 woman years of use. However, during an equivalent fifteen-month period, from May 1, 1982, to July 31, 1983, during whichtime 40 723 injections of pheno-M only were given (10 181 womanyears of use), 34 method failure pregnancies were observed, giving aPearl pregnancy rate of 0 - 33 per 100 woman-years of use. Thus, themethod failure with pheno-M was 2’ 4 times greater than that withdepo-provera. During the seven and a half months from August,1983, until now (March 15, 1984), we have observed only 2 furtheraccidental pregnancies with depo-provera, although delays in thereporting of accidental conceptions could account for this very lowshort-term incidence of recent method failures. These data supportour previous clinical impression that pheno-M has a lower

contraceptive efficacy, which would increase the number ofunwanted pegnancies and the unnecessary exposure of developingfetuses to a long-acting synthetic progestagen.Until the results of a arger, more definitive field study now in

progress are known in late 1984, it would seem prudent to confinethe long-term contraceptive use of DMPA to the standard, UK-approved depo-provera.Family Planning Program,McCormick Hospital,Chiang Mai, 50000 Thailand

Department of Population Dynamics,School of Hygiene and Public Health,Johns Hopkins University,Baltimore, Maryland, USA

Department of Community Medicine,Faculty of Medicine,Chiang Mai University

EDWIN B. MCDANIEL

RONALD H. GRAY

TIENG PARDTHAISONG

DOES LACTOSE INTAKE INDUCE CATARACT INMAN?

SiR.—Dr Rinaldi and colleagues (Feb 18, p 355) found that thefrequency of lactose absorbers in a group of healthy adults fromNaples was 16% or 22% (depending on the method of diagnosis)while it was 49% or 5507o in patients with bilateral idiopathiccataract. These results suggest that the ability to digest lactoseincreases the risk of senile cataract, probably by imposing a biggerload on the galactose metabolising system. There was no differencein milk consumption between the two groups.We have approached the problem in a different way and obtained

results which seem contradictory. A prospective study startedtwelve years ago was based on a representative sample of men livingin Malrno, all born in 1914. These men are now 69 or 70 years old(n=621): in a subsample (n = 200) we calculated lactose intake from

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diet histories. This group of men can all be regarded as essentiallylactose aborbers, since less than 3% of the population in southernSweden is lactose intolerant.’ The daily lactose intake rangedbetween less than 1 g and nearly 100 g.We selected for eye examination 25 men with the highest lactose

intake (mean 17-2 2 g per 1000 kcal, range 13 8- 33’ 3), one middlegroup of 25 men (8 - 5 g per 1000 kcal, range 3.5-13. 6), and the 25men with the lowest lactose intake (mean I - 70 g per 1000 kcal,range 1-3 - 5). Eyes were examined, with pharmacological dilatationof the pupil to reveal any small traces of cataract, by a doctor who didnot know to which lactose group the man belonged.Minor cataract changes were observed in 29% of the high lactose

group, in 44% of the middle group, and in 40% of the low lactose

group. These figures do not indicate a positive correlation betweenhigh lactose intake and early cataract-rather the reverse. We do notyet know for certain whether these early changes are related to laterfully developing cataracts. Of these 75 men only 1 had been

operated on for cataract, and he was in the low lactose group (1’ 5 g gper 1000 kcal). We plan to continue this investigation by looking atlactose intakes in all men with fully developed cataracts in the wholegroup (n=621).Our conclusion for the present is that we have no evidence for the

hypothesis that the amount of lactose consumed in lactase persistentindividuals affects the prevalence of early cataract changes, but weare not yet ready to state whether there is any relation betweenlactose intake and clinically fully developed cataract.

Health Sciences Centre,Dalby (University of Lund)

Department of Community Health Sciences,Malmo (University of Lund)

Department of Nutrition,Chemical Centre,University of Lund,S-220 07 Lund, Sweden

BO BENGTSSON

BERTIL STEEN

ARNE DAHLQVISTMARGARETHA JAGERSTAD

OPERATIVE STRATEGY FORPHAEOCHROMOCYTOMAS LOCALISED BY

[131I]-m-IODOBENZYLGUANIDINE SCINTIGRAPHY

SIR,-The adrenomedullary scanning agent [131I]_m_iodobenzyl-guanidine (MIBG) is very useful in the localisation of

phaeochromocytomas. Dr Brown and colleagues (Jan 7, p 56)reported a patient with a right adrenal phaeochromocytoma inwhom the phaeochromocytoma and the normal left adrenal medullawere demonstrated five days after injection of the isotope. Normaladrenal glands are rarely seen at 24 h (and only faintly when theyare) but the frequency of visualisation increases over the ensuingdays.2 Furthermore, nearly all phaeochromocytomas can bevisualised on scanning after 24 h. Therefore, the misinterpretationof the five-day scan by Brown and colleagues should not be regardedas a false-positive result, and we concur with the comments of DrChatal and colleagues (March 31, p 733). In our experience’withmore than 450 patients who were suspected of having a

phaeochromocytoma there were no false-positive scans, with ascanning dose ofO-5 5 mCi MIBG (one-quarter of the dose used byBrown et al).Of more concern to us is the unilateral approach to an apparently

localised phaeochromocytoma advocated by Brown and colleagues.No localisation technique is absolutely reliable. The two best

investigations, which will suffice in nearly all circumstances, arecomputerised tomography and MIBG scanning, and these havecomplementary roles.3

3 ’

We have treated a patient in whom MIBG scanning revealed adefinite phaeochromocytoma in the left adrenal only; at laparotomythrough a curved transverse incision bilateral adrenal medullary

1. Dahlqvist A. Digestion of lactose In. Delmont J, ed. Milk intolerance and rejection,Basel Karger, 1983: 11-16

2. Nakajo M. Shapiro B, Copp J, et al. The normal and abnormal distribution of theadrenomedullary imaging agent m-(I131)-iodobenzylguanidine (I131MIBG) inman Evaluation by scintigraphy J Nucl Med 1983, 24: 672-82.

3. Francis IR, Glazer GM, Shapiro B, Sisson JC, Gross MD. Complementary roles of CTand (1 31I)-MIBG scintigraphy in diagnosing pheochromocytoma. AJR 1983, 141:719-25.

hyperplasia (of the sporadic type) with bilateral adrenal

phaeochromocytomas was found, and there was a third

phaeochromocytoma arising in paraganglionic tissue anterior to theabdominal aorta. This patient would not have been cured by aunilateral left flank approach.While computerised tomography and MIBG scanning are of

major assistance in the planning and performance of operations forphaeochromocytomas, they provide no justification for abandoningthe standard surgical approach which should includetransabdominal exploration of both adrenal glands and the

retroperitoneal locations of extra-adrenal phaeochromocytomas(paragangliomas).Department of Surgery,University of Michigan,Ann Arbor, Michigan 48109, USA

NORMAN W. THOMPSONIAN R. GOUGH

PROLIFERATIVE RETINOPATHY AND DIABETESMELLITUS

SIR,-We have read with interest the report by Dr Knight andcolleagues (March 24, p 681) of an optic nerve infarction andimprovement in diabetic control after the continuous subcutaneousinfusion of insulin (CSII) in a patient with insulin-dependentdiabetes. But, as Dr Kohner points out (May 5, p 1018), thispatient’s optic nerve infarction occurred when his diabetic control(though improved) was still far from adequate.We have recently seen a patient in whom rapidly progressive

proliferative retinopathy developed within 8 weeks of theinstitution of tight diabetic control. This 31-year-old woman withinsulin-dependent diabetes was admitted to hospital with diabeticketoacidosis and possible subarachnoid haemorrhage (excludedlater by normal CT scan and CSF), having neglected her diabetes forthe previous 9 years. She had had intermittent treatment with oralhypoglycaemic agents and insulin during this period, but wasessentially symptom-free until an influenza-like illness precipitatedketoacidosis. After treatment of the ketoacidosis, she was started ontwice daily injections of a combination of insulins. Blood glucosewas maintained at 4-7 mmol/1 and her HbAI had fallen from 1407o to7 5% after 8 weeks. At this stage, she complained of blurred visionand was found to have advanced proliferative retinopathy,exudates, haemorrhage, and macular oedema bilaterally. Afterfluorescein angiography, laser treatment was started and themacular oedema subsided and her vision stabilised.The rapid development of proliferative retinopathy within 8

weeks of the institution of tight diabetic control and the absence ofthe condition despite 9 years of badly controlled diabetes suggests acausal relation between tight diabetic control and proliferativeretinopathy. In view of the previously reported, though less

striking, deterioration of retinopathy after tight diabetic controlwith CSII, the possibility that rapid, sustained falls in blood

glucose may aggravate retinopathy has to be considered.

Metabolic Unit,Department of Chemical Pathology,

and Department of Ophthalmology,Royal Free Hospital and School of Medicine,London NW3 2QG

P. DANDONA

J. P. BOLGERF. BOAGV. FONSECA

J. D. ABRAMS

OPTIC DISC SWELLING IN DIABETES MELLITUS

SIR,-Dr Lavin and Dr Goran’s restricted definition of

papilloedema (March 17, p 629), is not universally accepted byclinicians. Only on etymological grounds would it seem reasonableto use the word to describe oedematous swelling of the optic discarising from a variety of causes.2 We do, however, agree that suchswelling results from an interruption of axoplasmic flow in acuteischaemic optic neuropathy (AION) and other conditions.Whether ischaemic damage in AION involves the optic nerve

proximal or distal to the lamina cribrosa is uncertain. Althoughlongitudinal capillary anastomoses are present in the optic nerve,there is no evidence that the pial vessels can maintain an adequate

1. Lauritzen P, Frost-Larsen K, Larsen HW, Deckert T. Effect of one year of near normalblood glucose levels on retinopathy in insulin-dependent diabetes. Lancet 1982; i:200-04

2. Dorland’s Illustrated Medical Dictionary. Philadelphia: WB Saunders, 1981 960