Your search found 15 Results
Child mortality estimation: Methods used to adjust for bias due to AIDS in estimating trends in under-five mortality.
PLOS Medicine. 2012 Aug; 9(8):e1001298.In most low- and middle-income countries, child mortality is estimated from data provided by mothers concerning the survival of their children using methods that assume no correlation between the mortality risks of the mothers and those of their children. This assumption is not valid for populations with generalized HIV epidemics, however, and in this review, we show how the United Nations Inter-agency Group for Child Mortality Estimation (UN IGME) uses a cohort component projection model to correct for AIDS-related biases in the data used to estimate trends in under-five mortality. In this model, births in a given year are identified as occurring to HIV-positive or HIV-negative mothers, the lives of the infants and mothers are projected forward using survivorship probabilities to estimate survivors at the time of a given survey, and the extent to which excess mortality of children goes unreported because of the deaths of HIV-infected mothers prior to the survey is calculated. Estimates from the survey for past periods can then be adjusted for the estimated bias. The extent of the AIDS-related bias depends crucially on the dynamics of the HIV epidemic, on the length of time before the survey that the estimates are made for, and on the underlying non-AIDS child mortality. This simple methodology (which does not take into account the use of effective antiretroviral interventions) gives results qualitatively similar to those of other studies.
Cadernos de Saude Publica. 2005; 21 Suppl:S89-S99.This paper describes the sample design used in the Brazilian application of the World Health Survey. The sample was selected in three stages. First, the census tracts were allocated in six strata defined by their urban/rural situation and population groups of the municipalities (counties). The tracts were selected using probabilities proportional to the respective number of households. In the second stage, households were selected with equiprobability using an inverse sample design to ensure 20 households interviewed per tract. In the last stage, one adult (18 years or older) per household was selected with equiprobability to answer the majority of the questionnaire. Sample weights were based on the inverse of the inclusion probabilities in the sample. To reduce bias in regional estimates, a household weighting calibration procedure was used to reduce sample bias in relation to income, sex, and age group. (author's)
Global AIDSLink. 2003 Apr-May; (79):12-13.The media plays a unique role within society either to denounce or to perpetuate the bias and moral judgments against people with HIV/AIDS. Sometimes journalists can underestimate how influential their portrayal of HIV/AIDS is in shaping people's attitudes, especially when society fails to distinguish between people and the disease they suffer from; when denial is so pervasive that the infected are ostracized by their families. In addition, reporters, editors and producers constantly grapple with ways to find fresh angles to discuss HIV, and ensure their viewers and readers remain engaged by a topic that never appears to grow old. To address these and other key topics concerning the media and its treatment of HIV/AIDS, the World Bank organized a distance-learning course from June to November 2002 that simultaneously brought together journalists and HIV/AIDS project managers from Tanzania, Uganda, Zambia, Nigeria and Malawi. The course, entitled Fighting the HIV/AIDS Pandemic through Information and Strategic Communication, recognizes the role that successful communication campaigns can play in increasing understanding of the disease and promoting life-saving behaviors. Each program stream consisted of eight video-conferenced modules, which were followed up through in-country work. (excerpt)
BULLETIN OF THE WORLD HEALTH ORGANIZATION. 1997; 75(5):417-26.Diarrhea is one of the major causes of morbidity and mortality among children in developing countries, and more than 12,000 people are estimated to die per day from diarrheal disease in such countries. Diarrhea has also been shown to affect child growth and is an important cause of malnutrition which can adversely affect child mortality. The infectious nature of diarrhea suggests that fecal contamination of water and food contributes to its transmission. That is, a contaminated source of water, if serving several families, can cause a cluster of illness. Simple random sampling and cluster sampling are discussed as examples of strategies which can be used to measure the prevalence of diarrhea and dysentery in a community. The authors investigated the cost of conducting World Health Organization (WHO) Expanded Program on Immunization (EPI) cluster sample surveys, expressed as the distance travelled to visit the sample subjects, and the bias and variance of the estimates derived with that design. The efficiency of EPI cluster sampling was specifically evaluated with regard to the assessment of the prevalence of diarrhea and dysentery. A computer was used to simulate fieldwork conducted by a survey taker. The bias and variance of prevalence estimates obtained using EPI cluster sampling were compared with those obtained using simple random sampling and cluster sampling. EPI cluster sampling was determined to be an appropriate low-cost tool with which to monitor trends in the prevalence of diarrhea and dysentery over time. It should, however, be used with caution when estimating the prevalence of diarrhea at a single point in time because of bias.
Drs. Thomas and Noonan reply re "Comparison of Recalled and Validated Oral Contraceptive Histories" [letter]
AMERICAN JOURNAL OF EPIDEMIOLOGY. 1995 Apr 15; 141(8):791.Dr. Realini asserts in his letter that the results of the WHO Collaborative Study of Neoplasia and Steroid Contraceptives concerning oral contraceptives and breast cancer could have been biased as a result of better recall of prior oral contraceptive use by cases in comparison to controls. Although this is a possibility in any case-control study based on data collected by interviews, being able to validate positive oral contraceptive histories of more cases than controls does not necessarily mean more cases than controls who were users of oral contraceptives gave a history of such use. The issue of bias due to recall was discussed in the original paper. The medical records of women who claimed contraceptive use were checked for brand names and duration of use; the medical records of women who did not were not checked. This procedure did not alter their classification as users or nonusers. Since few combined oral contraceptives were available, and erroneous reports of use of combined or noncombined preparations were corrected, the estimated values of the relative risk of breast cancer in women who ever used combined oral contraceptives could not be appreciably influenced by any differences in the proportion of cases or controls whose oral contraceptive histories were supplemented by information from medical records. However, such differences could alter estimated values of the relative risk in relation to duration, latency, or recency. Information was obtained from the medical records of users in 27% of cases and 18% of controls. These percentages varied with center (0-94% of cases, 0-89% of controls). Information was most frequently obtained from the medical records of long-term and current or recent users in both groups. Similar results were obtained separately from countries in which information from medical records was obtained for relatively high and low proportions of users, and in individuals whose use was ascertained solely from interviews and from both interviews and medical records.
Washington, D.C., World Bank, 1994. x, 31 p. (World Bank Discussion Paper 258; Africa Technical Department Series)The Botswana 1984 Family Health Survey and the Zimbabwe 1984 Reproductive Health Survey (both contraceptive prevalence surveys), the 1988 Botswana Family Health Survey-II (a Demographic and Health Survey), and the 1988 Zimbabwe Demographic and Health Survey were performed to assess the extent of fertility and contraceptive use. Comparisons between surveys for both countries revealed that the fertility decline was not as dramatic as reported. Sample selection and questionnaire construction between surveys had changed sufficiently to account for some of the fertility decline. The sample in 1988 included more educated women even in the same cohort who had lower fertility. Also, the second DHS type survey asked for a complete birth history, which substantiated the actual number of children. In Zimbabwe, fertility was estimated at 6.5 in 1984 and 5.5 in 1988. The average was 3.4 children per woman in 1984 and 2.95 in 1988. The number of children ever born for women 45-49 years old declined from 7.5 to 6.9. During this period, improvements had been made in contraceptive usage, educational attainment, and health services. A comparison with census data showed that fertility was closer between 1984 and 1988 and significantly improved over fertility in 1969. In Botswana, total fertility declined from 6.5 to 5.0, and the number of children ever born decline from 6.9 to 5.8. The average number of children per woman declined from 3.1 to 2.6. Social development had occurred in Botswana also. There is some evidence that the age range of study participants, 15-49 years, may have excluded women at the extreme ends. About 20-50% of the fertility decline reported in Zimbabwe could be attributed to educational differences among women 25-34 years old. Similarly, in Botswana, among women 35-44 years old, 20-30% of the fertility decline could be attributed to educational changes.
AMERICAN JOURNAL OF EPIDEMIOLOGY. 1994 Nov 15; 140(10):956.A paper by Nischan and colleagues, "Comparison of Recalled and Validated Oral Contraceptive Histories," which examines the accuracy of the histories of oral contraceptive use (defined as agreement with gynecologists' records concerning duration of use, times since first and last use, and individual preparations used) in a WHO case-control study of breast cancer, "WHO Collaborative Study of Neoplasia and Steroid Contraceptives," fails to comment on the more frequent validity of the histories among those persons with breast cancer. Of 253 contraceptive histories from persons with breast cancer, for whom responses from at least 1 gynecologist were available, 234 (92.4%) were confirmed; of those from 621 controls, 524 were. The difference is statistically significant (chi-square test, p < 0.01). This better recall of ever-use of oral contraceptives among breast cancer patients creates a bias that makes an association between breast cancer and ever-use of oral contraceptives stronger than it is. The slight elevation in breast cancer risk associated with ever-use of oral contraceptives found in the WHO study may be due to this. There is no information about the accuracy of negative oral contraceptive histories.
New York, New York, AVSC, 1993 Sep. 8 p.Neither the US Food and Drug Administration nor WHO have yet endorsed intrauterine insertion of quinacrine for tubal occlusion in women. Quinacrine is very inexpensive and easy to produce and insert, which make it open to abuse. Free and informed choice and safety must be upheld as well as quality of care in family planning services. The few studies of quinacrine use for nonsurgical sterilization have small sample sizes and very short-term follow-up. They have largely occurred in Chile, Egypt, and Indonesia. One study suggests that quinacrine increases the risk of cancer. Recently a field trial of 31,781 women undergoing nonsurgical sterilization with quinacrine pellets was conducted in Viet Nam. The pregnancy rate at 1 year was 2.63. At 2 years it was 4.31 for cases with 2 insertions. At 5 years, for women with just 1 insertion, it was 5.15. There were 19 ectopic pregnancies. Major complications included 2 cases of severe bleeding, 2 hysterectomies (severe pain and amenorrhea, adhesions in the cervical canal), 1 case of premenstrual pain and dysmenorrhea, 1 case of pelvic inflammatory disease, and 1 allergic reaction. Only minor side effects occurred. The study methodology was flawed, however. For example, the researchers did not bide by the inclusion criteria they claim to have used. They also extrapolated failure rates and side effects based on subsets to the whole group. Thus, this study cannot be used to conclude that quinacrine pellets are safe and effective. Further, well-designed studies addressing short and long-term safety are warranted. If studies find quinacrine pellets to be safe and effective, their low cost and ease of insertion make it a promising method in areas of high maternal mortality, with low access and availability of family planning services, and great unmet need for permanent methods.
AIDS. 1993 Dec; 7(12):1613-5.In 1990, Belgium, physicians enrolled 415 consecutive patients attending HIV reference centers in Antwerp, Brussels, and Ghent in a cross-sectional study designed to evaluate the clinical axis of the WHO staging system with and without the lymphocyte stratification proposed by Montaner el al. (that is, modified WHO staging system) (>1500, 1500- 1000, and <1000 cells x 1 million/l). They filled in a standardized questionnaire with all criteria of the WHO staging system. Laboratory personnel used standard hematology and flow cytometry techniques to determine absolute and CD4 lymphocyte counts. 80% of the patients were Caucasians. 46% of all patients were homosexual and 42% were heterosexual; 79.2% were men. Median CD4 lymphocyte counts fell in both staging systems as the stage of HIV infection increased. There were significant differences in median CD4 counts between stages of each staging system (p < .001). The modified WHO staging system's stage I was more sensitive at identifying patients with CD4 lymphocyte counts of more than 500 cells x 1 million/l than the WHO clinical stage 1 (83% sensitivity vs. 48% sensitivity). The positive predictive value of WHO clinical stage 4 and of the modified WHO staging system's stage IV for identifying people with CD4 lymphocyte counts of less than 200 cells x 1 million/l was quite high (79% and 80%, respectively). The researchers suggested that clinicians use stages 4 and IV as end-points is clinical trials in developing countries. Clinicians completing the questionnaire knew the patients' earlier CD4 lymphocyte count, which may have introduced a bias in the study. For example, they may have more thoroughly examined patients with low CD4 lymphocyte counts than those with normal counts. Nevertheless, the study's results indicated that either one of these systems may be a good alternative in developing countries to the technical equipment-dependent CD4 lymphocyte count-based HIV staging system used in developed countries. Cohort studies in developing countries would evaluate their prognostic value.
In: Issues in reproductive technology I: an anthology, edited by Helen Bequaert Holmes. New York, New York, Garland Publishing, 1992. 11-30. (Garland Reference Library of Social Science Vol. 729)The progestin, levonorgestrel, suppresses ovulation and thickens the cervical mucus. The 1-year pregnancy rate is 0.2/100 users and the 5-year rate is 3.9/100 users. Contraindications of Norplant include abnormal bleeding, cardiovascular conditions, liver tumors, and breast cancer. The most frequent side effect is changes in bleeding patterns. A main concern of women's health advocates is that women are dependent on the medical establishment for insertion and removal of Norplant which affects the provider-client relationship. Family planning programs that do not recognize a woman's right to free choice of existing contraceptives and her right to have Norplant removed at any time may abuse Norplant. Health workers still do not know the long term effects of Norplant and Norplant's effect on the fetus in case of method failure or insertion while pregnant. Most acceptability studies occurred at university-based health clinics or at clinics in urban areas. The clinic environment may affect women's answers. These studies should occur in the community and home of users and nonusers. Another bias of these studies was clinic staff chose women who would tend to continue using Norplant. Thus subjects were not representative of the population. Researchers did not attempt to understand the women's perception of reproduction physiology and mode of action, the women's cost benefit analysis used to determine what method to use, or the consequences of menstruation changes. They also did not report on the information women received about contraceptive choices. The issue of abuse has arisen in Kansas where a state legislator proposed paying any mother on welfare US$500 if she uses Norplant. In California, a judge ordered a woman convicted of child abuse to use Norplant after release from jail and throughout her probation period.
AMERICAN JOURNAL OF OBSTETRICS AND GYNECOLOGY. 1992 Oct; 167(4 Pt 2):1171-6.The largest case control study on the association between oral contraceptive (OC) use and cancer is the US Cancer and Steroid Hormone (CASH) study. Since it did not use hospital-based patients as controls, it eliminated some biases. Since OCs suppress ovulation and suppressed ovulation is linked with reduced risk of ovarian cancer, scientists believe OCs may reduce this cancer risk. The CASH study shows that OC use indeed decreases the risk of ovarian cancer 40% (relative risk [RR]=.6 and this protection lasts for more than 10 years after OC discontinuation. Protection increases with duration of OC use (<1 year RR=.6 and >10 years RR=.2). Estrogenic stimulation of the endometrium without ample progestational protection causes endometrial cancer. Thus combined OCs which have estrogen and progestin components should reduce the risk of endometrial cancer. The CASH study reveals OC use for at least 12 months reduces this risk 50%. OCs have a protective effect for at least 15 years after stopping OC use. In addition, UK national mortality data show OC use caused the decline in ovarian cancer mortality and a 40% decrease in endometrial cancer mortality over the last 20 years. A WHO 7-county case control study indicates that OC users in developing countries have the same protective effect against ovarian and endometrial cancer as those in developed countries. Studies of OC use and cervical cancer have had conflicting results due to 3 biases: cervical cancer is associated with sexual behavior and is therefore a sexually transmitted disease; detection bias. A study in Costa Rica conducted by CDC study has addressed the 1st and 3rd biases. It found no increased risk of invasive cervical cancer or carcinoma in situ with OC use. Studies of OC use and breast cancer have also had conflicting results, but the data clearly indicate that OC use does not increase the overall risk of breast cancer. In fact, OC benefits surpass breast cancer risks.
HEALTH POLICY AND PLANNING. 1992 Sep; 7(3):251-9.Policymakers and program managers rely on the oral rehydration solution (ORS) use rate as an indicator of program performance. The ORS use rate has several limitations, e.g., it disregards other program objectives. Other diarrheal disease control program objectives may include reducing the source of infection, promotion of effective home-based treatment, and training of health workers in appropriate diarrhea case management. WHO and the Demographic and Health Surveys (DHS) try to standardize the methodology for estimating ORS use rates, but they have not looked at them as cross-country indicators. Error sources lie in the terms used for diarrhea, the reference period, and the sequence of questions referring to treatment. In Bangladesh, the people recognize different types of diarrhea and treat each type differently. In 1 instance, health workers informed mothers to prepare and give a homemade sugar salt solution. Later they learned that mothers did not use ORS very much because they only used ORS for the type of diarrhea the health workers described. There has been considerable variation of ORS use rates in Bangladesh, perhaps because of the differences in meanings of the words used for diarrhea. The DHS uses a 2-week reference period, yet a Bangladesh survey finds underreporting of diarrheal episodes which occur early in the week of the survey. Other surveys do not use a specific reference period and mothers tend to remember only serious diarrheal episodes. A direct question about ORS use in surveys is too leading as indicated by higher ORS use rates when interviewers prompt respondents. ORS use rates do not give a true picture of a program and can even be counterproductive. No consensus exists as to what is high ORS use rate and what is low ORS use rate. Managers should not use ORS use rates as the only program indicator.
Development. 1989; (4):77-82.Contemporary multilateral loan agreements to developing nations, unlike previous project and program aid, have often been contingent upon the effective implementation of structural adjustment programs of market liberalization and macroeconomic policy redirection. These programs herald such reform as necessary steps on the road to economic growth and development. Price decontrol and policy change may also, however, generate the more immediate and undesirable effects of exacerbated urban sector bias and plummeting income and quality of life in the general population. This paper considers the resultant changes expected in the political arena, product and input pricing, small business promotion and formation, export crop production, interest rate policy reform and financial market deregulation, exchange rate and public sector expenditure, and the labor market, and their effect upon women's economic position. The author notes, however, that women are not affected uniformly by these changes and sectoral disruptions, but that some women will suffer more than others. To develop policy to effectively meet the needs of these target groups, more subpopulation specificity is required. Approaches useful in identifying vulnerable women in particular societies are explored. Once identified, these women, especially those who head poor households, should be afforded protection against the turbulence and short- to medium-term economic decline associated with adjustment.
BRITISH JOURNAL OF CANCER. 1990 Sep; 62(3):468.The slightly elevated risk of breast cancer in combined oral contraceptive (OC) users--1.07 in developed countries and 1.24 in developing countries--recorded in the World Health Organization's (WHO's) Collaborative Study of Neoplasia and Steroid Contraceptives may result from bias in the selection of controls. In this study, the control group was comprised of non-breast cancer patients hospitalized for conditions unrelated to steroid complications. However, there are at least 2 confounding factors responsible for the lower level of OC use in the control group: 1) these women may be less sexually active and do not use contraception regularly, or 2) controls may have medical conditions that make their health providers reluctant to prescribe OCs. In the developing country series, it seems probable that hospitalized controls had many chronic medical conditions, such as tuberculosis, fungal infections, malaria, parasitic diseases, and nutritional disorders. It is especially important to consider possible bias when dealing with relative risk of 1.1 or 1.2, as found in this study. When hospital controls are used, researchers should provide complete information on admission and underlying diagnosis, as well as previous hospital admissions.
BRITISH JOURNAL OF CANCER. 1990 Sep; 62(3):469-70.J D Shelton of the US Agency for International Development has suggested that the findings of a 1989 World Health Organization study of a 1.07 relative risk in developed countries and a 1.24 relative risk in developing countries of breast cancer in users of combined oral contraceptives (OCs) may reflect sources of bias inherent in the selection of hospitalized controls. The authors of the article reporting these findings acknowledge that the study results may reflect chance or confounding, yet reject the explanations suggested by Dr Shelton. Shelton maintains that chronic health conditions in hospitalized controls, especially in developing countries, may lead to lower levels of sexual activity (and thus less of a need for regular contraception) and contraindicate the prescription of steroidal contraception. Such a scenario would produce spuriously inflated risks for breast cancer among OC users. It is argued, however, that the similar proportions of OC users across diagnostic categories of controls rules out the possibility that controls offer an underestimate of the expected amount of use in cases. If the controls' current disease status precluded recent use of OCs, OC use should have varied across diagnostic categories. The validity of the results is further suggested by the consistent association in developing countries between breast cancer and features of OCs such as duration of use, recency of use, and latency periods. Although the findings of this study warrant further investigation, the sources of bias identified by Dr Shelton are unlikely.