334 SEX DIFFERENCES IN INFANTILE DIARRHŒA

SIR,-Boys defalcated more frequently and passed liquid stools on a higher percentage of days than did girls in a population of Colombian children studied by Newell et al.’ Inherent, sex-associated differences may not have been responsible, however, since the findings might have reflected dietary factors, such, as a possible earlier weaning of males. This variable was controlled in a prospective study of infant feeding practices and morbidity in Salvador, Bahia, Brazil. The study population had low economic and educational levels, limited potable water, and poor sanitary conditions. From Nov. 1, 1974 to Oct. 31, 1975, within a geographically defined neighbourhood of about 26 000, we tried to identify all women in their sixth month of pregnancy. The cohort of infants born to these 1026 women was followed up until twelve months old. The babies were visited biweekly at home during the first three months of life to measure growth and to record detailed information of what the children ate and the illnesses they had had during the interval. Diarrhoea was defined as the passage of three or more liquid stools in a 12 h period or the passage of one or more liquid stools with gross blood, pus, or mucus. Cooperation was excellent, but some families moved from the study area and other children died or were temporarily absent at the time of scheduled visits. Consequently, there are diminishing numbers and a slight fluctuation in the table. Diarrhoea was the principal cause of infant death. 13 boys and 6 girls died from it before completing the third month. During this time, 69.2% of the boys and 60.9% of the girls had at least one episode. Boys had diarrhoea, on the average, 9-8% of the days and girls 7.7%. The percentage of days with diarrhoea was greater for males for every two-week interval. The percentage of diarrhceal days increased up to the latter half of the second month of life, probably because of the progressive introduction of bottle feeding and juices. These were started earlier for boys than for girls, but on all eleven regimens with sufficient numbers to permit evaluation, excepting that of "switched from breast alone to breast plus bottle plus juice during the two-week period", there was more diarrhoea among boys than

girls. To exclude, as far as possible, all but the differences due to factors inherent to the sexes, a further comparison was limited to the first two weeks of life among the exclusively breast-fed. These boys had diarrhoea 144 of the 1920 days of observation (7.5%) and the girls 77 of 2295 (3.4%). Our findings, corroborating those of Newell et al.,suggest that there is a masculine diathesis for diarrhoea in early infancy. Further investigations are needed to explain how susceptibility to diarrhoea-the major cause of infant death in developing regions of the Americas—is increased by the presence of a Y chromosome.

This work M. L. M.

supported by

Ford Foundation grant 739-0820

Department of Preventive Medicine, Universidade Federal da Bahia, Salvador, Bahia, Brazil

to

S. J. PLANK* M. L. MILANESI

*Present address: Foundation for International Technological Cooperation, New Executive Office Building, Washington, D.C. 20500, U.S.A.

SUBMUCOSAL ŒSOPHAGEAL VARICES

SIR,-Mr Johnson and Dr Murray-Lyon (Jan. 20, p. 155) suggest that the "capricious results of injection sclerotherapy" can be explained by the site of injection in relation to the lower oesophageal sphincter. Macbeth in Oxford many years ago pointed out the advisability of injecting the varix at three sites -at about 30, 35, and 38 cm-to ensure as far as possible thrombosis of the full length of the varix. Adherence to this technique may explain his superior results, in part. St. James’ Hospital, London SW12 8HW

JOHN S. KIRKHAM

H.D.L. CHOLESTEROL AND CORONARY RISK FACTORS

SiR,-Dr Williams and his colleagues (Jan. 13, p. 72) have demonstrated once again the value of high-density lipoprotein (H.D.L.) cholesterol measurements in epidemiological studies. They have failed to point out that, however significant their data were statistically, the significance of H.D.L. measurements in individual patients is less certain. They compare the H.D.L.-cholesteroVtotal-cholesterol ratio in groups of individuals with different cumulative risk-factor scores for coronary-artery disease. We have calculated the range of results they obtained in the groups with no risk factors and the highest number of risk factors. This was done by adding and subtracting 2 standard deviations from the mean of each group, which slightly understates the spread of results. There is considerable overlap between the two groups for H.D.L./total cholesterol ratios, and an even greater overlap for absolute H.D.L.-cholesterol concentrations. It is this large overlap which invalidates the test in an individual:

Clinicians would be well advised to carry on asking traditionally relevant questions about smoking and exercise, and using simple measurements of weight and blood-pressure, rather than to try and base decisions on inevitably confusing H.D.L.

Newell, K. W., Dover, A. S., Clemmer, D. I., D’Alessandro, A., Dueñas, A., Gracian, M., Le Blanc, D. R. Bull. PanAm. Hlth Org. 1976, 10, 143. 2. Puffer, R. R., Serrano, C. V. Patterns of Mortality in Childhood. Pan American Health Organisation, Washington, D.C., 1975.

was

results.

1.

Radcliffe Oxford

Infirmary,

PERCENTAGE OF DAYS OF DIARRHOEA BY SEX DURING FIRST THREE MONTHS OF LIFE

R. A. MOORE R. W. SIMPSON J. I. MANN

Sex differences in infantile diarrhoea.

334 SEX DIFFERENCES IN INFANTILE DIARRHŒA SIR,-Boys defalcated more frequently and passed liquid stools on a higher percentage of days than did...
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