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Biomedical subjects

T M Farley

Publications and source records attributed to T M Farley.

At least 19 recordsLinked to original sources
PubMed2001

Collection of standardized information on infant feeding in the context of mother-to-child transmission of HIV.

Complete avoidance of breast-feeding is the surest way to avoid mother-to-child transmission (MTCT) of HIV through breast-feeding, but replacement feeding exposes infants, especially those born in developing countries, to the risk of other infectious diseases with consequent increase in morbidity and mortality. One study has suggested that exclusive breast-feeding during the first months of life carries a lower risk of HIV transmission than when other foods are given in addition to breast milk. Other studies have provided limited data on the risks of HIV transmission according to different patterns of breast-feeding, but studies have used different definitions of breast-feeding patterns and have analysed their data with adjustment on different risk factors. This hampers our ability to understand the mechanisms underlying HIV transmission through breast milk and the risks associated with different infant feeding practices. Consequently it is difficult to determine the best interventions to reduce the risk of transmission and the development of optimal policies. In collaboration with research teams involved with infant feeding research, the World Health Organization has developed a tool to assist studies on MTCTto collect information in a standardized manner, using common definitions and terms. The purpose is to facilitate comparisons between studies and the quantification of the risks of transmission according to various feeding patterns, after adjusting for potential confounding variables. The tool includes a core questionnaire to record infant feeding practices and other key information on the mother's and the infant's health. It also provides guidance on methods of analysis and presentation of the complex data on infant feeding. The tool can be used in prospective research studies on MTCT prevention, as well as providing the framework to assess infant feeding patterns in intervention programmes, such as those providing intensive counselling to mothers on infant feeding. The tool will facilitate the compilation of information from these studies which will ultimately provide scientific basis for updating guidelines and policies on infant feeding by mothers infected with HIV.

Africa South of the Sahara↗
PubMed2001

Competing approaches to analysis of failure times with competing risks.

For the analysis of time to event data in contraceptive studies when individuals are subject to competing causes for discontinuation, some authors have recently advocated the use of the cumulative incidence rate as a more appropriate measure to summarize data than the complement of the Kaplan-Meier estimate of discontinuation. The former method estimates the rate of discontinuation in the presence of competing causes, while the latter is a hypothetical rate that would be observed if discontinuations for the other reasons could not occur. The difference between the two methods of analysis is the continuous time equivalent of a debate that took place in the contraceptive literature in the 1960s, when several authors advocated the use of net (adjusted or single decrement life table rates) rates in preference to crude rates (multiple decrement life table rates). A small simulation study illustrates the interpretation of the two types of estimate - the complement of the Kaplan-Meier estimate corresponds to a hypothetical rate where discontinuations for other reasons did not occur, while the cumulative incidence gives systematically lower estimates. The Kaplan-Meier estimates are more appropriate when estimating the effectiveness of a contraceptive method, but the cumulative incidence estimates are more appropriate when making programmatic decisions regarding contraceptive methods. Other areas of application, such as cancer studies, may prefer to use the cumulative incidence estimates, but their use should be determined according to the application.

Computer Simulation↗
PubMed2001

Assessing the acceptability, service delivery requirements, and use-effectiveness of the diaphragm in Colombia, Philippines, and Turkey.

The diaphragm is not available in many countries, despite the recommendations of numerous authors that it has important advantages as a woman-controlled method that offers some protection against sexually transmitted diseases, and one that is safe and free of side effects. An interagency team collaborated to introduce the diaphragm in Colombia, the Philippines, and Turkey, using the same protocol to assess the acceptability, service delivery requirements and use-effectiveness of the method. Eighteen public and private sector service delivery sites were involved and a total of 550 women were enrolled in the study. Provider training aimed to improve the quality of care with which all methods were delivered and included counseling about sexuality and reproductive health risks. The cumulative 12-month pregnancy rate of 10.1 (SE 1.7) per 100 woman-years is on the low end of previous studies of the diaphragm, and the 12-month continuation rate (57.2 [SE 2.4] per 100) compares favorably with that for oral contraceptives and the intrauterine device. Focus group discussions conducted with clients and providers indicated that the method was an important alternative for some women, particularly those who had experienced health problems with other methods or were unable to negotiate condom use with their partners. Provider biases diminished as they observed the strategic niche that the diaphragm filled for their clients. While providing the diaphragm requires training and good client-provider interaction, the requirements are consistent with those called for in the Programme of Action of the International Conference on Population and Development (ICPD, 1994). With proper attention to quality of care, the diaphragm can be successfully offered in resource-poor settings.

Adolescent↗
PubMed2001

Safety and efficacy of levonorgestrel implant, intrauterine device, and sterilization.

OBJECTIVE: To evaluate safety and efficacy of levonorgestrel-releasing contraceptive implants (Norplant; Leiras Oy, Turku, Finland) in developing countries. METHODS: We used controlled cohort methodology. Women attending family planning clinics in eight developing countries selecting Norplant were enrolled, together with women of similar age choosing intrauterine devices (IUDs) or surgical sterilization. Participants were interviewed and examined at semi-annual visits and followed-up for 5 years regardless of change of contraceptive methods. Incidence rate ratios of health events were estimated for initial and current method use. RESULTS: Altogether, 7977 women initiated Norplant, 6625 IUD, and 1419 sterilization. The overall follow-up rate was 94.6% and 78,323 woman-years of observation were accumulated. Pregnancy rates for Norplant, copper IUDs, and sterilization each averaged less than 1 per 100 woman-years. With two exceptions, no significant excess risk of serious morbidity was detected for Norplant users compared with controls. The incidence of gallbladder disease was higher in women who initiated Norplant use than in controls (rate ratio 1.52, 95% confidence interval [CI] 1.02, 2.27), as was the incidence of hypertension and borderline hypertension in current implant users (rate ratio 1.81; CI 1.12, 2.92). Other new findings were increased risks of respiratory diseases and decreased risks of inflammatory disease of the genital tract in Norplant users compared with IUD users and sterilized women. CONCLUSION: The study confirms the safety with respect to serious disease and the high contraceptive efficacy of Norplant, copper IUDs, and sterilization.

Adult↗
PubMed2001

Feasibility of surveillance of changes in human fertility and semen quality.

There is concern that male fertility is declining, but this is difficult to study because few men volunteer for studies of semen quality, and recruitment bias may over-represent the subfertile. The Human Reproduction Programme of the World Health Organization developed a protocol for multicentre studies of fertility involving a questionnaire for pregnant women to obtain time to pregnancy (TTP): the number of menstrual cycles taken to conceive. Male characteristics and semen quality will be determined in a subset of the partners. Our aim was to validate the TTP questionnaire, and to examine potential recruitment bias and feasibility of conducting large-scale surveillance of fertility. The questionnaire was administered to 120 pregnant women (16-32 weeks). Validation included internal reliability by consistency of responses, test-re-test reliability by repeat administration (20 women) and accuracy by comparison of gestational age from first antenatal ultrasound and menstrual dates. Internal reliability was high. Agreement between categorical responses on re-testing was very good (k > 0.8). In both the re-test and gestational age analysis, differences in TTP of 1 cycle were found (standard deviation <0.25 cycles). In this small pilot study there was no evidence of recruitment bias. Response rates indicate the feasibility of surveillance of fertility in large maternity centres.

Adult↗
PubMed2000

Feasibility of surveillance of changes in human fertility and semen quality.

To show that male fertility is declining is not simple. Few men volunteer and recruitment bias may lead to over-representation of the subfertile. Semen analysis has errors arising from counting and poorly standardized criteria, which may be overcome by automation. Time to pregnancy (TTP)-the number of menstrual cycles taken to conceive-measures fertility and allows male recruitment bias to be estimated. We review automated measurement of sperm concentration, motility and morphology and present a preliminary report on a study to assess a retrospective TTP questionnaire, recruitment bias and feasibility for large-scale surveillance of fertility.

Feasibility Studies↗
PubMed1999

Effect on stroke of different progestagens in low oestrogen dose oral contraceptives. WHO Collaborative Study of Cardiovascular Disease and Steroid Hormone Contraception.

The multicentre WHO collaborative case-control study had limited power to differentiate stroke risks by progestagen component in low dose combined oral contraceptives. Given this caveat, odds ratios for ischaemic, haemorrhagic, and all strokes combined associated with use of oral contraceptives containing desogestrel or gestodene ("third generation") were found to be similar to those containing levonorgestrel in this study.

Adult↗
PubMed1998

Hormonal contraception and risk of cardiovascular disease. An international perspective.

The most frequent major adverse effect of hormonal contraception is an increased risk of cardiovascular disease. The effect on the risk of venous thromboembolism (VTE), ischemic and hemorrhagic stroke, and myocardial infarction (MI) differs and is strongly influenced by smoking and the presence of other cardiovascular risks factors, such as hypertension and diabetes mellitus. The incidence of each disease rises with age and there are differences in risk among hormonal contraceptive preparations. This article provides a framework within which to assess the balance of risks among types of hormonal contraceptives according to individual circumstances. Data on cardiovascular disease mortality rates in women of reproductive age in different countries of the world were compiled from nationally reported statistics and supplemented where possible with reported disease incidence rates. Risks associated with current use of hormonal contraception were compiled from the most recent publications on the cardiovascular effects of steroid hormone contraception. These were combined to estimate the total cardiovascular incidence and mortality according to baseline cardiovascular risk and individual characteristics. Mortality rates for cardiovascular diseases are very low in women of reproductive age. Myocardial infarction mortality rates rise from < 0.4 per 100,000 woman-years at age 15-24 years to the range 2 to 7 per 100,000 woman-years at age 35-44 years. Stroke mortality rates similarly rise steeply with age and are between 3 and 5 times higher than those for MI. VTE mortality rates rise less steeply with age and are approximately one-tenth the MI mortality rates at age 35-44 years. The adverse effect of oral contraceptives (OC) on the risk of VTE is the most important contributor to the total number of cardiovascular cases attributable to OC use. The increased risk of stroke and MI dominate the patterns of mortality in OC users and smokers. The additional risks attributable to smoking are greater than the additional risks attributable to OC use. The risk attributable to OC use in women < 35 years of age is small, even if they smoke, but there are substantially increased risks in older women who both smoke and use OC. The additional mortality attributable to OC use can be reduced by screening users, as this results in lower relative risks of ischemic stroke and MI. Differences between OC types in the relative risk of VTE contribute little to the total cardiovascular mortality associated with OC use, even though the total number of cardiovascular events is increased. A potential reduction in the risk of MI with desogestrel and gestodene compared with levonorgestrel-containing OC would have little difference on overall mortality rates in women in their 20s and 30s, but may result in a net reduction in OC-attributable mortality in women aged 40-44 years who smoke. An overall quantification of the risks for different types of oral contraceptive users is necessary for an informed choice of contraceptive method, and any assessment of the balance of cardiovascular risks is complex. The model provides a tool to assess, at the level of the individual, the risks associated with use of different OC according to personal circumstances. It is important to consider the user's age and smoking status when determining OC attributable risks.

Cardiovascular Diseases↗
PubMed1998

Breech labor on the WHO partograph.

OBJECTIVES: To assess the impact of breech labor management using the WHO partograph on fetal and maternal outcomes of labor. METHOD: All 1,740 breech presentations in a larger multicenter hospital-based study in South East Asia of the use of the WHO partograph in labor management were studied. The partograph was introduced into each hospital during the study and a before and after analysis of various labor outcomes was conducted. RESULTS: There were 923 breech presentations prior to implementation of the partograph and 817 after. The overall Cesarean section rate was 29.7% (21.6% emergency and 7.6% elective). Introducing the partograph reduced Cesarean sections for multigravida from 27.1% to 19.3% (non-significant) but had no impact on the rate for primigravida (38.5% to 38.7%). Prolonged labor (> 18 hours) was reduced significantly among multigravida and primigravida (p < 0.05), despite a reduced use of oxytocin. Intrapartum stillbirths fell (non-significantly) from 1.9% to 1.1% (all parities combined). Fetal outcome, as measured by intrapartum deaths and Apgar scores < 7 at 1 minute, was significantly better (P < 0.05) when delivery was by Cesarean section rather than vaginally, regardless of use of the partograph. CONCLUSION: The use of the WHO partograph in the management of breech labor reduces prolonged labor and (among multigravida) Cesarean sections and improves fetal outcome. In this study, however, Cesarean section was a safer method of delivery for the baby, regardless of use of the partograph.

Apgar Score↗
PubMed1998

Combined oral contraceptives, smoking, and cardiovascular risk.

STUDY OBJECTIVE: To assess age specific incidence and mortality of stroke, acute myocardial infarction (AMI), and idiopathic venous thromboembolism (VTE) associated with use of modern low dose combined oral contraceptives (OCs) and the interaction with smoking. DESIGN: Hospital-based case-control study. SETTING: Hospitals in Oxford region in the United Kingdom, which covered a defined population, during the period 1989-1993. METHODS: Relative risk estimates from the WHO Collaborative Study and observed incidence rates from the Oxford region were used to estimate age specific incidence of each disease among women without cardiovascular risk factors and model total cardiovascular incidence and mortality. RESULTS: Among women who did not use OCs, smoke nor had any other cardiovascular risk factors, total incidence of stroke and AMI were less than 2 events per 100,000 woman years in those aged 20-24 years and rose exponentially with age to 8 events per 100,000 among women aged 40-44 years. Incidence of idiopathic VTE among women who did not use OCs rose linearly with age (from 3.3 per 100,000 at ages 20-24 years to 5.8 per 100,000 at ages 40-44 years). The increased risk of idiopathic VTE associated with OC use among non-smokers constituted over 90% of all cardiovascular events for women aged 20-24 years and more than 60% in those aged 40-44 years. Fatal cardiovascular events were dominated by haemorrhagic stroke and AMI, and among OC users who smoked these two diseases accounted for 80% of cardiovascular deaths among women aged 20-24 years, rising to 97% among those aged 40-44 years. Cardiovascular mortality associated with smoking was greater than that associated with OC use at all ages. Attributable risk associated with OC use was 1 death per 370,000 users annually among women aged 20-24 years, 1 per 170,000 at ages 30-34 years, and 1 per 37,000 at ages 40-44 years. Among smokers, the cardiovascular mortality attributable to OC use was estimated to be about 1 per 100,000 users annually among women aged less than 35 years, and about 1 per 10,000 users annually among those above the age of 35 years. CONCLUSION: The incidence of fatal cardiovascular events among women aged less than 35 years is low. The VTE risk associated with OC use is the largest contributor to OC induced adverse effects. The potentially avoidable excess VTE risk associated with the newer progestogens desogestrel and gestodene would account for a substantial proportion of total cardiovascular morbidity in this age group. For women over age 35 years the absolute risks associated with OC use and smoking are greater because of the steeply rising incidence of arterial diseases. The combination of smoking and OC use among such women is associated with particularly increased risks. Any potential reduction in AMI or stroke risk with use of third generation OCs would be a more important consideration among older compared with younger women, particularly if they smoke. However, the mortality associated with smoking is far greater than that associated with OC use (of any type) at all ages.

Adult↗
PubMed1998

Ageing, nutritional status and immune response.

The effects of vitamin supplementation on the age-related decline in immune function was studied in a population of elderly subjects with a high prevalence of low and deficient serum values of vitamin C, vitamin E, riboflavin and pyridoxin, as well as iron and zinc. The immune function was examined by measuring delayed cutaneous hypersensitivity (DCH) after intradermal application of a set of 7 antigens in 72 subjects aged 60-89 years living in two homes for the elderly. The results showed an almost linear statistically significant decline in the DCH test with age (p < 0.01). Vitamin supplementation for a period of 10 weeks significantly improved the biochemical parameters for those vitamins and the age related decline in the DCH test was no longer statistically significant (P > 0.05). No statistically significant changes in DCH were observed in the placebo group. The results of this study suggest that nutrition may be an important determinant of immunocompetence in the elderly.

Aged↗
PubMed1996

Prostitution, condom use, and invasive squamous cell cervical cancer in Thailand.

Cervical cancer is probably caused by a sexually transmitted agent. A case-control study was conducted in three hospitals in Thailand to investigate further the role of male sexual behavior, particularly regarding sexual contacts with prostitutes, in the development of this disease. Data were obtained from interviews with 225 married women with invasive squamous cell cervical carcinoma and 791 hospitalized controls, all of whom reported having only one sexual partner, and from interviews with their husbands. Risk of cervical cancer was strongly related to the women's husbands having visited prostitutes without using a condom when the husbands were less than 30 years old. A strong increasing trend in risk in relation to decreasing frequency of the husbands' condom use with prostitutes was observed, and a weaker increasing trend in risk with husbands' estimated lifetime total number of visits to prostitutes was found. The average latent period between the women's likely initial exposure to a sexually transmitted oncogenic agent and her diagnosis of invasive cervical cancer was about a quarter of a century. Regular use of condoms by customers of prostitutes could reduce the number of invasive cervical cancer cases in the general population of Thailand by at least one fourth.

Adult↗
PubMed1996

Reliability of data from proxy respondents in an international case-control study of cardiovascular disease and oral contraceptives. World Health Organization Collaborative Study of Cardiovascular Disease and Steroid Hormone Contraception.

STUDY OBJECTIVES: To evaluate the reliability of data supplied in a case-control study by proxy respondents for cases who were too ill to do so themselves. DESIGN: A hospital based, case-control study of the current use of oral contraceptives (OC) and cardiovascular diseases. Data from "true" controls matched to a subset of cases were compared with those supplied by proxy respondents about the true controls. SETTING: Hospitals in 21 centres from Africa, Asia, Europe, and Latin America. PATIENTS AND PARTICIPANTS: For a subset of cases, 403 pairs of controls-one "true" and one proxy-were interviewed. "True" controls were matched by age, place, and time of admission and were admitted with 1 of 27 permissible diagnoses not associated with OC use. Proxy controls were either relatives or friends of true controls. MAIN RESULTS: Levels of concordance between data from proxy and true controls were high for most variables regarding recent events, including current OC use, but were greatly diminished when detailed information, particularly from the past, was required. Husbands were usually the best proxy, although this was question-specific. The sensitivity and specificity of proxy responses were 93% (95% confidence intervals: 77%, 99%) and 100% (98%, 100%) respectively, for current use of OC. Assuming the misclassification of current OC use by proxy cases is similar to that produced by proxy controls, the estimated impact of using proxy data on risk estimates associated with current OC use was to bias the overall estimate of risk of stroke by less than 3% and the risks of both acute myocardial infarction and venous thromboembolism by less than 1%. CONCLUSIONS: Friends or relatives, and particularly husbands, provided reliable information when used as proxy respondents for young women. The estimated impact of misclassification by proxy respondents on overall risk estimates in the WHO collaborative study was less than that which would have arisen if information from proxy respondents had not been used.

Adult↗