The use of nutritional status as a second outcome measure in case-control studies of environmental risk factors for diarrhoeal diseases

Case-control studies are typically used to study the effect of several factors on the risk/incidence rate of a single disease. This paper describes a particular situation in which it is of interest to study the effect of a factor--improved sanitation facilities--on the risk/incidence rate of two 'diseases'--the incidence rate of diarrhoea and the risk of undernutrition. The conditions under which it is valid to perform an analysis of the association between the risk factor (unimproved sanitation) and a second outcome variable (undernutrition) are examined. If the effect of exposure status (improved/unimproved sanitation facilities) on the propensity to report an episode of diarrhoea is independent of the effect of nutritional status it appears that such an analysis may be valid. There must also be no interaction between the risk factor (unimproved sanitation) and the second outcome (undernutrition) with respect to their effects as risk factors for the first outcome variable (diarrhoea incidence rate).

Fertility and fetal salvage among women with uterine leiomyomas in a Nigerian Teaching Hospital

Fertility and pregnancy outcome among 141 Nigerian women with uterine leiomyomas and 270 married gynaecological subjects matched for age and parity were studied. The preoperative spontaneous abortion incidence and fetal salvage among the 68 women in the study group who had previously been pregnant were 61.8% and 78.8%, respectively. Corresponding figures among women in the comparison group were 5.3% and 95.6%. Macroscopic evidence of pelvic sepsis was found at operation in 36.2% of all the women in the study group, and in 57.7% of those who complained additionally of infertility. The overall pregnancy rate following myomectomy was 37.9%, and 9.6% in those women whose presenting complaints included infertility. The mean operation-to-conception interval in the study group was 15.7 months. The fetal salvage increased to 93.5% in the women who conceived after myomectomy, and their incidence of abortion fell markedly, to 11%. Most of the deliveries (79%) in the women after myomectomy were by cesarean section. A reappearance of uterine leiomyomas occurred in 13.7% of the women. The relatively low incidence of pelvic sepsis in this series may partly be responsible for the finding of menorrhagia, rather than abdominal pain, as the commonest complaint of the women with leiomyoma.

Breast cancer and breastfeeding: results from an Australian case-control study

A case-control study of breast cancer, diet, and lactational history was carried out in Brisbane, Australia, between 1981 and 1985. Cases were recruited from both the private and the public health care sectors. The breastfeeding histories of 459 cases and 1,091 controls selected from the electoral roll were analyzed. An odds ratio of 0.85 (95% confidence interval 0.55-1.30) for any lactation versus no lactation was observed, with no suggestion of a monotonic trend with increasing duration. This estimate was only slightly altered by multiple logistic regression analysis. A statistically significant nonlinear association was noted for breastfeeding of the first liveborn child (chi 2 = 14.8, df = 6; p less than 0.05), with a slightly elevated odds ratio for lactations of less than one month, a lowered odds ratio for lactations of one month to three months, and a weakly elevated odds ratio in women breastfeeding for more than nine months. Results for premenopausal women were very similar to those for postmenopausal women. Taken together with other recent studies, these results suggest that lactation may play a modest direct or indirect part in reducing the risk of breast cancer.

Faecal mycobacteria and their relationship to HIV-related enteritis in Lusaka, Zambia

The prevalence of infection with mycobacteria, both typical and atypical, is increasing along with prevalence of infection with HIV. Patients with pulmonary tuberculosis (PTB) and patients with chronic diarrhoea are forming a growing proportion of the patient population in hospitals in central Africa. To investigate the possibility that mycobacteria may be responsible for some of the HIV-related enteropathy seen in Lusaka, we studied 89 patients in four different diagnostic groups, clinically, by Mantoux test and by microscopy and culture of stool specimens for mycobacteria. In the HIV-positive group with chronic diarrhoea (n = 31), two patients were found to have mycobacteria on faecal smear and three were culture positive while of the 15 HIV-negative controls, three were smear positive and three were culture positive. Of the 15 patients with proven PTB, three had positive faecal smears but none were culture positive. In the fourth group of 24 patients with suspected PTB, seven were smear positive and five, culture positive. Only in this last group was there some correlation between smear results and culture results. Although this last finding is difficult to explain, it appears that there is no correlation between the symptom of chronic diarrhoea and the presence of mycobacteria in the stool. We conclude that mycobacteria do not play a significant role in the pathogenesis of HIV-related enteropathy in Lusaka.

Enteroaggregative Escherichia coli and Salmonella associated with nondysenteric persistent diarrhea

A hospital-based case-control study including 92 children with diarrhea for longer than 14 days and 92 controls without gastrointestinal symptoms was performed to describe the association between the excretion of enteric pathogens and persistent diarrhea. In patients the most frequently isolated stool pathogens were enteroaggregative Escherichia coli (19.6%), nontyphoidal Salmonella spp. (17.4%), E. coli with diffuse adherence pattern (7.6%), G. lamblia (7.6%) and enterotoxigenic E. coli (5.4%). The excretion rates in patients were significantly greater than in controls only for nontyphoidal Salmonella spp. (P = 0.0006) and enteroaggregative E. coli (P = 0.016).

Menstrual pattern change 1 year after sterilization: results of a controlled, prospective study

To determine if female sterilization is associated with adverse menstrual change, we compared prospectively collected menstrual data from women who underwent sterilization via bipolar cauterization, banding, and Pomeroy ligation with data from women whose husbands obtained a vasectomy and from women who were not planning sterilization. At first-year follow-up, sterilization via banding with Falope rings was not associated with adverse change. After excluding initially abnormal cases: (1) cauterization women were bleeding more heavily than all other groups excepting Pomeroy; (2) cauterization and Pomeroy women experienced more dysmenorrhea than women not planning sterilization; and (3) more cauterization and Pomeroy women (collapsed samples) developed abnormal length cycles than did the two control groups. There were no group differences regarding development of beneficial/neutral change (e.g., decreased dysmenorrhea). However, cauterization and Pomeroy groups experienced a significantly higher average number of adverse changes than did the other groups and were at significantly greater risk of developing one or more adverse changes than were women not planning sterilization. The only pattern of association among adverse menstrual changes occurred significantly more often in the cauterization and next in the Pomeroy groups.

Haemorheological consequences of oestrogen and progestogen therapy

A clinical investigation was undertaken of the haemorheological effects of short-term administration of synthetic sex hormones. In a randomised controlled investigative trial, groups of 20 women taking ethynyloestradiol, norethisterone, combined norgestrel and ethynyloestradiol or no therapy had their blood viscosity and its major determinants measured before and after 3 months of treatment. Oestrogens and progestogens, singly or in combination, were found to cause a rise in blood viscosity. Oestrogens did so by raising haematocrit and plasma fibrinogen, parameters that are similarly raised in other conditions such as pregnancy and following surgery when venous thromboembolism is common. The synthetic progestogen, on the other hand, raised the blood viscosity by increasing the haematocrit and decreasing erythrocyte deformability, parameters that are similarly altered in occlusive arterial disease. The combined preparation raised blood viscosity by altering all three parameters. These observations indicate the pathways whereby various synthetic oestrogens and progestogens in oral contraceptives or replacement therapy may be associated with different types of cardiovascular pathology.

Early oral contraceptive use and breast cancer among premenopausal women: final report from a study in southern Sweden

In southern Sweden during the 1960s, women began to use oral contraceptives (OCs) extensively at a young age. This case-control study investigates the relationship between the use of OCs and breast cancer development in women in southern Sweden diagnosed in the early 1980s. The risk for breast cancer after OC use among premenopausal women was modeled, after adjustment was made for age, age at menarche, and age at first full-term pregnancy or parity. Both the duration of OC use before 25 years of age and commencement of OC use at a young age were associated with a significant increase in the risk of breast cancer as well as a significant trend. The duration of OC use before the first full-term pregnancy was associated with an increased risk of breast cancer, but it did not show a significant trend. The total duration of OC use was weakly, but not significantly, associated with breast cancer development. The odds ratio for women starting OC use before 20 years of age was 5.8 [95% confidence interval (CI), 2.6-12.8]; for women using OCs for greater than 5 years before age 25, it was 5.3 (95% CI, 2.1-13.2); and for women using OCs for greater than or equal to 8 years before first full-term pregnancy, it was 2.0 (95% CI, 0.8-4.7). In multivariate analyses including the different measurements of OC use, only starting age of OC use was significantly associated with breast cancer. The exposure-response relationship between duration of OC use and risk of breast cancer depended on the age at first use of OCs. Given a fixed duration of OC use, the risk increased with younger starting age of OC use. The findings point to the importance of the early reproductive years as risk determinants for breast cancer after OC use.

Serum IgG and IgA antibodies to Chlamydia in ectopic pregnancies

The possible association of Chlamydia trachomatis with ectopic pregnancies was evaluated in a case-control study, comprising 35 women with ectopic pregnancy and 294 apparently healthy women who served as controls. Chlamydia-specific IgG and IgA antibodies were determined by single serovar (L2) inclusion immunoperoxidase assay (IPA). Socio-demographic characteristics, gynecological history and contraceptive methods were also evaluated. An inverse relationship was found between the educational levels and the prevalence of IgG and IgA antibodies to chlamydia. The prevalence rate of elevated IPA IgG (titer greater than or equal to 128) and IPA IgA (titer greater than or equal to 16) specific to chlamydia was significantly higher in women with ectopic pregnancy versus controls (32% vs 8%, respectively, for IgG: odds ratio = 4.9; and 26% vs 4% for IgA: odds ratio = 7.5). Chlamydia trachomatis was not isolated in cell cultures in 10 specimens available from fallopian tubes of women with ectopic pregnancy. Only 9% of the women recall having pelvic inflammatory disease (PID) indicating that most of the infections were asymptomatic. Women who did not use IUD had a higher proportion of chlamydia-specific IgG and IgA seropositives, though not statistically significant, as compared to IUD users. This study further supports the hypothesis that subclinical infection of the tube with C. trachomatis may underlie ectopic pregnancies.

Population-based case-control study of ovarian cancer in Shanghai

A case-control study of 229 ovarian cancer cases (including 172 epithelial tumors) and an equal number of population-based controls was conducted during 1984 to 1986 in Shanghai, China, a low-risk area for ovarian cancer. Similar to studies in high-risk areas, the risk of epithelial tumors was high for nulliparous women (odds ratio, 1.6; 95% confidence interval, 0.8 to 3.2) and decreased with increasing number of livebirths (P less than 0.01). Early menarche and late menopause were associated with increased risk, with the trend in risk for age at menarche being statistically significant. In contrast to other studies, oral contraceptive use was not associated with reduced risk, although there was some reduction in risk for those with a prior tubosterilization or intrauterine device use. Risk was also elevated among those reporting a prior ovarian cyst, medroxyprogesterone use, a first degree family history of cancer, and occupational exposure to paint. Risk factors for the nonepithelial tumors were similar to the other cancers, although the power to detect differences was limited.

Pharmacodynamics of a contraceptive vaginal ring releasing 3-keto-desogestrel

The pharmacodynamic effects of a new type of 3-keto-Desogestrel [3kDOG] releasing vaginal ring was studied in a group of 20 normally ovulating women during a period of 21 days continuous use. Peripheral blood samples were taken for the estimation of progesterone and oestradiol levels, ultrasound tracking for follicular growth and cervical mucus sampling for scoring [modified Insler] and sperm penetration testing during a control, treatment and recovery period. Additional blood samples were taken for the estimation of 3kDOG levels during the treatment period. After a control cycle, twenty normally ovulating women were selected and randomly divided into two groups. Group A were given a vaginal ring on day 5 of the menstrual cycle releasing 30 ug/24 hours of 3kDOG and group B a similar ring releasing 15 ug/24 hours of kDOG. Of the treatment cycles, none showed an ovulatory pattern in group A and there was only one in group B, the respective mean plasma levels of 3kDOG were 0.38 and 0.25 pmol/ml. The formation of "cysts" or persistent follicles was common to both groups, 6 out of 10 subjects in group A and 8 out of 10 subjects in group B had "cysts" greater than 25mm in diameter in the treatment cycle, this had become 5 out of 10 and 8 out of 10, respectively, in the recovery cycle. A comparison of the cervical mucus scores and sperm penetration of cervical mucus showed a significant reduction between the control and treatment groups but no significant difference between the two groups. The bleeding profiles showed an increase in percentage of bleeding days in both treatment groups to 25% in group A and 21.7% in group B [cf, 17.1%, 15.9%, respectively, in control month]; there being no statistical difference between groups. In conclusion, it is believed that given the efficacy demonstrated and the low level of menstrual disturbances found, this system warrants further investigation as a means of contraception as it appears to offer a better compromise than previous vaginal ring systems.

Programmed oocyte retrieval: clinical and biological effects of oral contraceptives administered before in vitro fertilization

We have prospectively compared two regimens of suppression of the hypothalamic-pituitary-ovarian axis by oral contraceptives (OCs) for 15 or 30 days and two ovarian stimulation protocols. The latent phase, which represents a period of ovarian insensitivity, was prolonged and directly correlated to the duration of suppression. Thirty days' suppression, compared with 15 days', resulted in the cancellation of more cycles and a lower fertilization and pregnancy percentage. No significant increase in either serum progesterone or luteinizing hormone was noted in suppressed cycles. It is concluded that if programming is desired, OCs should be used for the shortest period possible. The variation in the length of the follicular phase indicates that there is a different 'fixed' day for retrieval for each suppression-stimulation protocol and this day should be established prospectively.

Association of antecedent malnutrition with persistent diarrhoea: a case-control study

To determine the effect of nutritional state on persistent diarrhoea a case-control study was carried out on 756 children followed up prospectively for 18 months. Children who developed persistent diarrhoea were compared with population controls and controls with acute diarrhoea. The mean weight for age in the children with persistent diarrhoea (69.9%) was significantly lower than that in the population controls (77.0%) and the diarrhoeal controls (76.2%). Weight for age of less than or equal to 70% was associated with persistent diarrhoea in both case-control analyses (population controls, matched odds ratio 3.25; diarrhoeal controls, matched odds ratio 2.46). The corrected odds (multiple logistic regression) in the two analyses were 3.2 (95% confidence interval 1.3 to 8.1) and 3.4 (1.2 to 9.1). Weight for age of less than or equal to 70% increases the risk of persistent diarrhoea. In an underweight child there is a higher risk of diarrhoea becoming persistent. Prevention of malnutrition and intensive management of acute diarrhoea in malnourished children should help reduce the risk of the diarrhoea persisting.

Infant feeding and deaths due to diarrhea. A case-control study

The association between infant feeding habits and infant mortality from diarrhea was investigated in a population-based case-control study in two urban areas in southern Brazil during 1985. Each of 170 infants who died due to diarrhea was compared with two neighborhood controls. After allowance was made for confounding variables, infants who received powdered milk or cow's milk, in addition to breast milk, were at 4.2 times (95% confidence interval (CI) 1.7-10.1) the risk of death from diarrhea compared with infants who did not receive artificial milk, while the risk for infants who did not receive any breast milk was 14.2 times higher (95% CI 5.9-34.1). Similar results were obtained when infants who died from diarrhea were compared with infants who died from diseases that were presumed to be due to noninfectious causes. Each additional daily breast feed reduced the risk of diarrhea death by 20% (95% CI 2-34%), but the increase in risk associated with each bottle feed was not significant after allowance was made for the number of breast feeds. The only other consumption variable associated with diarrhea mortality was the frequency with which tea, water, or juice were drunk with each feed (increase in risk, 42% (95% CI 4-93%]. The odds ratios associated with nonbreast milk were highest in the first two months of life. Possible biases were investigated, including the interruption of breast-feeding as an early consequence of the terminal illness, but the strong protective effect of breast-feeding persisted after these adjustments.

Oral contraceptives and breast cancer

A population-based case-control study of oral contraceptive use and breast cancer was carried out among young women (less than 43 years of age) at Group Health Cooperative of Puget Sound, Seattle, Washington. Use of oral contraceptives before first pregnancy did not materially differ between cases or controls. The rate ratio estimate of breast cancer incidence in women who had used oral contraceptives before first pregnancy compared to those who had not was 0.9 (95% CI = 0.4, 2.1). There were no meaningful patterns of association between breast cancer and duration of use or formulation of oral contraceptive used before first pregnancy.

Doxylamine and diphenhydramine pharmacokinetics in women on low-dose estrogen oral contraceptives

Thirteen women chronically using low-dose estrogen-containing oral contraceptives (50 micrograms or less of ethinyl estradiol or its equivalent for a minimum of 3 months) and 12 age-matched drug-free control women received a single 25 mg oral dose of doxylamine succinate in the fasting state. Ten women taking oral contraceptives and ten controls received a single 50 mg oral dose of diphenhydramine hydrochloride. Multiple plasma samples drawn during 30 hours following the dose of doxylamine, and 12 hours after diphenhydramine dosage, were analyzed by gas chromatography using nitrogen-phosphorus detection. Mean pharmacokinetic variables for doxylamine in control and oral contraceptive groups were: peak plasma concentration, 103 vs 100 ng/ml; time of peak, 2.40 vs 1.87 hours after dosage, elimination half-life, 10.1 vs 10.2 hours; and total clearance, 3.70 vs 3.88 ml/min/kg. Mean pharmacokinetic variables for diphenhydramine in control and oral contraceptive groups were: peak plasma concentration, 63.7 vs 73.8 ng/ml; time of peak, 2.7 vs 2.2 hours after dosage; elimination half-life, 6.0 vs 5.1 hours; and total clearance, 21.8 vs 25.5 ml/min/kg. None of these differences were statistically significant. Thus, low-dose estrogen-containing oral contraceptives do not significantly influence the pharmacokinetics of the antihistamines doxylamine or diphenhydramine.

Impact of oral rehydration therapy on maternal beliefs and practices related to acute diarrhea

Maternal beliefs and practices related to acute diarrhea were evaluated in 69 villages of a district in Haryana. Oral rehydration therapy (ORT) programme was introduced in 47 villages; in 25 by health workers and in 22 by health volunteers. Twenty two villages served as control. Impact was assessed by interviewing 200 mothers initially and 210 each, one and two year after initiating the programme. Dehydration as a complication of diarrhea was perceived by 67.2% mothers in health worker and 71.4% in volunteer villages of Intervention area as compared to only 32.8% in control area (P less than 0.01). In Intervention area, 88.6% mothers had tried ORT as compared to 22.8% in control area and 85% of the mothers found it to be useful. The restriction of breast feeding during acute diarrheal episode was favoured by only 15.7% mothers in intervention area and by 47.1% in control area (P less than 0.01). The knowledge regarding use of home available fluids in increased amounts did not show an impressive change. There was no change as regards understanding of cause of diarrhea. Favourable change in beliefs and practices is possible by instituting ORT with culturally relevant health education.

Lamicel does not promote induction of labour. A randomized controlled study

Lamicel is a synthetic tent, which, when inserted in the cervical canal, dilates the cervix by osmosis. Lamicel as an adjunct to induction of labour with intravenous oxytocin or vaginal prostaglandin E2 has been examined in a randomized controlled trial. Ninety-one pregnant women with an unripe cervix participated in the study. No improvement in efficacy was observed in the Lamicel groups compared to the control groups, neither when induction of labour was performed with oxytocin nor with vaginal prostaglandin.

Asymptomatic salpingitis in intrauterine contraceptive device users

Serial histological sections of the fallopian tubes of 50 asymptomatic subjects undergoing voluntary tubal ligation were evaluated for morphological evidence of inflammation. Twenty-five subjects had history of IUD use (the study group) and the rest 25 had never used a device (the control group). Evidence of inflammation was found in 11 out of 25 subjects in the IUD users compared to only 2 out of 25 subjects in the non-users (p less than 0.001). The relative risk was 5.5 times. Both acute and chronic inflammation of the oviducts were observed more often in the IUD users, though clinically and at surgery there was no apparent evidence of pelvic inflammatory disease.

Mothers' personal and domestic hygiene and diarrhoea incidence in young children in rural Bangladesh

This study examines the effect of maternal personal and domestic hygiene on the incidence of diarrhoea in children aged 6-23 months from rural areas around Teknaf, Bangladesh. The intervention area received augmented water supply through handpumps and health education while the control area received no project inputs. From July 1980 to June 1983, diarrhoea incidence was recorded weekly while mothers' personal and domestic hygiene was observed yearly. Annual incidence of diarrhoea in 314 children from the intervention area and 309 children from the control area was analysed in relation to maternal personal and domestic hygiene, controlling for education and occupation of household head and household size. Results show that, in both areas, use of handpump water for drinking and washing, removal of child's faeces from the yard, and maternal handwashing before handling food and after defaecation of self and child, observed together, decreased yearly diarrhoea incidence in children by more than 40% compared to children living in households where none or only one of these practices was observed.

Prevalence of Escherichia coli strains with localized, diffuse, and aggregative adherence to HeLa cells in infants with diarrhea and matched controls

To determine the possible role of Escherichia coli strains with three different patterns of adherence to HeLa cells in causing diarrhea in infants in São Paulo, Brazil, we studied stool specimens from 100 infants up to 1 year of age with acute diarrheal illnesses and 100 age-matched control infants without recent diarrhea. E. coli with localized adherence to HeLa cells was much more common in patients (23%) than in controls (2%) (P less than 0.0001) and was detected more frequently than rotavirus (19%) was in patients, even though the study was conducted during the coldest months of the year. Most (80%) of the E. coli colonies with localized adherence were of traditional enteropathogenic E. coli serotypes. Little difference was found between patients and controls in the rate of isolation of E. coli with diffuse adherence (31 and 32%, respectively) or aggregative adherence (10 and 8%, respectively). A genetic probe used to detect a plasmid-mediated adhesin which confers expression of localized adherence proved to be 100% sensitive and 99.9% specific in detecting E. coli with localized adherence to HeLa cells. Although E. coli strains with localized adherence have now been shown to be enteric pathogens in several parts of the world, the role of strains showing diffuse adherence and aggregative adherence is still uncertain.