Age-specific hysterectomy and oophorectomy prevalence rates and the risks for cancer of the reproductive system.

A sample survey was conducted in 1982 to determine the prevalence of hysterectomy and oophorectomy among upstate New York women, ages 25-74. The effects of this surgery on age-specific estimates of the risk for cancer of the uterus, cervix, and ovary were calculated. Overall, 16.9 per cent of the women reported having had a hysterectomy and 9.9 per cent reported a bilateral oophorectomy. The adjustment for age-specific hysterectomy increased the 1977-1979 average annual incidence rate of cervical and uterine cancer by 21 per cent. In several five-year age categories, the increase reached 54 per cent. The 1977-1979 average annual incidence rate of ovarian cancer increased by 12 per cent after adjusting for age-specific bilateral oophorectomy. The increase reached 29 per cent in one five-year age group. The sample results show a lower prevalence of hysterectomy among women 25 to 40 years old and among women 70 to 74 than estimates based on the application of mathematical models to data on surgical incidence.     

An age- and sex-structured HIV epidemiological model: features and applications.

An important challenge in modelling the human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) epidemic is to use the increasing quantity of disease surveillance data to validate estimates and forecasts. Presented is a novel model for forecasting HIV incidence by age and sex and among sentinel groups for which data are available. This approach permits a closer relationship between forecasting and surveillance activities, and more accurate estimates validated to data. As inputs the model uses an estimate of the HIV prevalence, country demographic data, and a profile of the sexual risk of HIV infection by age, to project HIV incidence, prevalence, number of AIDS cases and population. The following examples of the use of the model are given: forecasting HIV incidence in East Africa, by age, sex, and among pregnant women; 3-5-year forecasts of HIV incidence; modelling mixed risk behaviour HIV epidemics in South-east Asia; demographic indicators; and targeting a preventive vaccine by age group.     

Antenatal screening for HIV; are those who refuse testing at higher risk than those who accept testing?

BACKGROUND: The UK Department of Health recommends that all pregnant women are offered screening for infection with human immunodeficiency virus (HIV) and had encouraged maternity units to achieve uptake targets of 90 per cent by the end of 2002. Many maternity units fail to meet this target and there is concern that those women who are still refusing testing may include a higher proportion of women at high risk of infection. In consequence, those infected with HIV are not being identified and are not receiving the antiviral treatment, which would be of benefit to them and reduce the risk of transmission of HIV to their babies. METHODS: A retrospective audit of HIV screening uptake in women who were found to be infected with hepatitis B virus (HBV) and in those who were not infected with HBV was carried out in order to explore further the characteristics of 'acceptors' and 'refusers' of HIV screening. RESULTS: The overall uptake rate of HIV screening in the West Midlands population served by the National Blood Service was 60 per cent in 2001 and 74 per cent in 2002. The prevalence of HBV infection was found to be twice as high (0.39 per cent) in those who had refused an HIV test compared with those who had accepted a test (0.21 per cent) (p = 0.022). CONCLUSION: There is good evidence that women refusing HIV antenatal screening have a higher prevalence of another blood-borne virus, indicating clearly that further effort must be made to increase the screening uptake and fully integrate HIV screening with other antenatal tests.     

Women who decline antenatal screening for HIV infection in the era of universal testing: results of an audit of uptake in three London hospitals

Universal screening for HIV in early pregnancy is strongly promoted policy in the United Kingdom with a target of 90 per cent uptake. We identified characteristics of women declining screening by conducting an audit at three hospitals in inner north London. In early 2002 midwives were asked to complete an audit form following first antenatal appointment. Of 2,710 women attending 401 (15 per cent) declined an HIV test. Of women who declined 38 per cent reported they had been tested for HIV in the past; 65 per cent accepted every other antenatal test. In multivariable analysis parity (OR: 1.19; 95 per cent CI 1.10-1.29 per additional child), declining other tests (OR: 3.10; 95 per cent CI 2.44-3.93 per test declined) and previous HIV testing (OR: 1.70; 95 per cent CI 1.30-2.23) were predictors of declining an HIV test. Women declining screening were not obviously from high-risk demographic groups: women from sub-Saharan Africa were not at greater risk of declining an HIV test than women from other regions.     

Mean square error of estimates of HIV prevalence and short-term AIDS projections derived by backcalculation

We simulated multinomial AIDS incidence counts from 27 'representative' AIDS epidemics that spanned a period corresponding to previous applications of backcalculation (1 January 1977 to 1 July 1987) and assessed mean square error for several back-calculated estimators of HIV prevalence and short-term AIDS projections. Estimators were based on flexible model selection procedures that chose the best-fitting non-negatively constrained model of the infection curve from a family of possible step-function models. Selection of the best-fitting model from a family of four-step models each with a long last step of width of 4 or 4.5 years offered a favourable tradeoff between bias and variance when compared with selection from families of models with three steps or from families with a short last step. Five-step models performed as well as four-step models. Three-step models had substantially larger mean square error in some epidemic situations. Percentage root mean square error (PRMSE) for estimates of cumulative HIV prevalence as of 1 January 1985 was less than 14 per cent over a range of hypothetical epidemics of N = 50,000 infected individuals. PRMSE for short-term projections was less than 18 per cent. Estimates of cumulative HIV prevalence as of 1 July 1987 were substantially more uncertain and had a PRMSE of 33 per cent in the unfavourable case of a rapidly rising HIV epidemic. Estimates of cumulative HIV prevalence as of 1 July 1987 were positively biased in HIV epidemics with a rapidly decreasing recent HIV incidence rate and negatively biased in rapidly increasing HIV epidemics. Despite these uncertainties, we obtained useful estimates even for HIV epidemics with as few as 5000 infected individuals.     

Impaired fertility in women infected with HIV-1. Implications for sentinel serosurveillance]

BACKGROUND: Given the relationship between HIV infection and fertility, antenatal clinic-based HIV prevalence may not provide a good estimate of the community HIV prevalence. The objective of this work was to evaluate the impact of HIV infection on fertility among women attending antenatal clinics in Bobo-Dioulasso (Burkina Faso), and to discuss possible implications on HIV sentinel surveillance. METHODS: In the context of a phase II/III clinical trial of a short course of Zidovudine during pregnancy (DITRAME - ANRS 049 trial) we consecutively proposed voluntary counselling and HIV testing (VCT) to 1349 women aged at least 18 years, carrying a pregnancy of 7 months or less and living in Bobo-Dioulasso. During pre-test counselling session, a standardised questionnaire was administered to collect detailed information regarding socio-demographic characteristics and obstetrical history. Blood samples were then taken and tested for HIV after written informed consent. RESULTS: Mean age (+/- standard deviation) at first sexual intercourse was similar among HIV-infected (HIV+) (16.7+/- 2; n=83) and HIV-negative (HIV-) women (16.9+/- 2; n=1336). However, HIV+ women aged 25 years and above had, on the average fewer pregnancies (3.8+/- 1.5; n=37) than HIV- women (5.0+/- 2.3; n=567), p<0.01. Similarly, these HIV+ women had, on average, less live births (2.8+/- 1.3; n=35) than HIV- ones (3.7+/- 2.1; n=555), p=0.02. Other sexual and obstetrical characteristics such as maternal age, proportion of primigravidae, stillbirths or spontaneous abortions were comparable between HIV+ and HIV- women. CONCLUSIONS: Our data suggest that the level of fertility of HIV+ women aged 25 years and above is significantly lower than for HIV- women. Therefore, HIV+ women in this age group are likely to be under-represented among antenatal clinic attendees. These findings suggest adjusting antenatal clinic-based HIV sentinel surveillance data for age and fertility in order to derive a good estimate of the community HIV prevalence.     

Incidence of herpes simplex virus type 2 infection in the United States

Between the time that two large, national surveys were conducted, the Second National Health and Nutrition Examination Survey (1976-1980) and the Third National Health and Nutrition Examination Survey (1988-1994), prevalence of herpes simplex virus type 2 (HSV-2) infection in the United States increased by 30%. From these survey data, the authors estimated the incidence of HSV-2 infection in the civilian, noninstitutionalized population aged > or = 12 years by means of a mathematical model that allowed overall incidence to increase linearly with time but required the shape of the age-specific incidence curve to remain constant. From 1970 to 1985, annual incidence of HSV-2 infection in HSV-2-seronegative persons increased by 82%, from 4.6 per 1,000 (95% confidence interval: 4.2, 5.0) to 8.4 per 1,000 (95% confidence interval: 7.7, 9.1). Incidence in 1985 was higher in women than in men (9.9 vs. 6.9 per 1,000), higher in Blacks than in Whites (20.4 vs. 6.3 per 1,000), and highest in the group aged 20-29 years (14.6 and 22.5 per 1,000 in men and women, respectively). Thus, by 1985, approximately 1,640,000+/-150,000 persons (730,000 men and 910,000 women) were being infected annually with HSV-2.     

Bootstrap confidence intervals and bias correction in the estimation of HIV incidence from surveillance data with testing for recent infection

The incidence of new infections is a key measure of the status of the HIV epidemic, but accurate measurement of incidence is often constrained by limited data. Karon et al. (Statist. Med. 2008; 27:4617–4633) developed a model to estimate the incidence of HIV infection from surveillance data with biologic testing for recent infection for newly diagnosed cases. This method has been implemented by public health departments across the United States and is behind the new national incidence estimates, which are about 40 per cent higher than previous estimates. We show that the delta method approximation given for the variance of the estimator is incomplete, leading to an inflated variance estimate. This contributes to the generation of overly conservative confidence intervals, potentially obscuring important differences between populations. We demonstrate via simulation that an innovative model-based bootstrap method using the specified model for the infection and surveillance process improves confidence interval coverage and adjusts for the bias in the point estimate. Confidence interval coverage is about 94–97 per cent after correction, compared with 96–99 per cent before. The simulated bias in the estimate of incidence ranges from ?6.3 to +14.6 per cent under the original model but is consistently under 1 per cent after correction by the model-based bootstrap. In an application to data from King County, Washington in 2007 we observe correction of 7.2 per cent relative bias in the incidence estimate and a 66 per cent reduction in the width of the 95 per cent confidence interval using this method. We provide open-source software to implement the method that can also be extended for alternate models.     

Declining HIV prevalence among women attending antenatal care in Pune, India

A declining prevalence of HIV among young women has been reported by the public sector implementing prevention of mother-to-child transmission (PMTCT) programmes, sentinel surveillance sites and research institutions in India. However, there are no reports evaluating such trends from the private healthcare sector. This study is a retrospective analysis of data collected by PRAYAS as a part of the PMTCT programme at Sane Guruji Hospital (SGH), a secondary care hospital in Pune, India. Women attending the antenatal clinic at SGH were screened for HIV following a group counselling session, with an option to opt out. Between January 2003 and March 2008, the overall HIV prevalence was 111/17 578 (0.6%, 95% CI 0.5-0.7%). The HIV prevalence among antenatal women was 1.1% in 2003 and 0.2% in 2008 (i.e. 82% decline in HIV prevalence over the 5-year period) and the odds ratio (OR) of HIV prevalence declined by 0.24 per year from 2003 to March 2008 (OR = 0.76, 95% CI 0.69-0.87; P < 0.001). The risk of having HIV infection was significantly higher in women aged ≥24 years and those who were uneducated. To our knowledge, this is the first report from any private sector health system in India documenting a declining HIV prevalence among antenatal women. Characterising the risk profile of this small percentage of at-risk women will help in planning prevention strategies.     

Human immunodeficiency virus infection in heterosexual intravenous drug users in San Francisco.

To investigate the risk of infection with the human immunodeficiency virus (HIV) in San Francisco, the prevalence of antibodies to HIV was determined in 281 heterosexual intravenous drug users recruited from community-based settings. Ten per cent of subjects had ELISA and Western blot confirmed seropositivity for antibodies (95 per cent CI 6.8-14.2 per cent). Analysis of behavioral factors revealed an increased risk of seropositivity in addicts who reported regularly sharing needles when injecting, particularly those sharing with two or more persons (odds ratio = 5.43; 95 per cent CI 1.08-52.5). Blacks and Latinos also had a greater prevalence of seropositivity than Whites, and this finding persisted after adjustment for needle sharing (adjusted odds ratio = 2.8; 95 per cent CI .84-8.59). Seropositivity was not associated with age, sex, duration of drug use, or history of prostitution. These data indicate that a new epidemic of AIDS (acquired immunodeficiency syndrome) in intravenous drug users, similar to that which has occurred among homosexuals in San Francisco, is possible. The relatively low seroprevalence in 1985 provides health officials an important opportunity to intervene and attempt to prevent widespread infection of drug users with HIV.     

HIV testing in national population-based surveys: experience from the Demographic and Health Surveys

OBJECTIVES: To describe the methods used in the Demographic and Health Surveys (DHS) to collect nationally representative data on the prevalence of human immunodeficiency virus (HIV) and assess the value of such data to country HIV surveillance systems. METHODS: During 2001-04, national samples of adult women and men in Burkina Faso, Cameroon, Dominican Republic, Ghana, Mali, Kenya, United Republic of Tanzania and Zambia were tested for HIV. Dried blood spot samples were collected for HIV testing, following internationally accepted ethical standards. The results for each country are presented by age, sex, and urban versus rural residence. To estimate the effects of non-response, HIV prevalence among non-responding males and females was predicted using multivariate statistical models for those who were tested, with a common set of predictor variables. RESULTS: Rates of HIV testing varied from 70% among Kenyan men to 92% among women in Burkina Faso and Cameroon. Despite large differences in HIV prevalence between the surveys (1-16%), fairly consistent patterns of HIV infection were observed by age, sex and urban versus rural residence, with considerably higher rates in urban areas and in women, especially at younger ages. Analysis of non-response bias indicates that although predicted HIV prevalence tended to be higher in non-tested males and females than in those tested, the overall effects of non-response on the observed national estimates of HIV prevalence are insignificant. CONCLUSIONS: Population-based surveys can provide reliable, direct estimates of national and regional HIV seroprevalence among men and women irrespective of pregnancy status. Survey data greatly enhance surveillance systems and the accuracy of national estimates in generalized epidemics.     

A composite likelihood approach for estimating HIV prevalence in the presence of spatial variation

Since 1990, the World Health Organization has recommended HIV surveillance among pregnant women as an essential surveillance activity for countries with generalized HIV epidemics. Despite the widespread availability and potential usefulness of antenatal HIV surveillance, analyses of such data present important challenges. Within an individual clinic, the HIV status of its attendees may be correlated because of similarities in HIV risk among women close in age. Between‐clinic correlation may also arise as women often seek antenatal care at clinics located close to their home, and individuals living in nearby communities may share important characteristics or behaviours related to susceptibility. A general estimating equation‐based approach for spatially‐correlated, binary data such as that antenatal HIV surveillance based on a pairwise composite likelihood has been described. We present an extended version of this model that can accommodate penalized spline estimators and apply it to antenatal HIV surveillance data collected in 2011 in Botswana to estimate the effects of proximity to the ‘hotspot’ of the country's HIV epidemic and age on HIV prevalence. Finally, we compare the results with a logistic regression analysis, which ignores potential correlation of responses. Copyright © 2015 John Wiley & Sons, Ltd.     

The San Francisco Men''s Health Study: continued decline in HIV seroconversion rates among homosexual/bisexual men.

The incidence of infection by the human immunodeficiency virus (HIV) has been monitored since 1984 in an area probability sample of homosexual/bisexual men drawn from a six-kilometer square area of San Francisco where the epidemic of acquired immunodeficiency syndrome (AIDS) has been most severe. Annualized HIV seroconversion rates in previously uninfected cohort members have declined by 88 per cent from 5.9 per cent during the first six months of 1985 to 0.7 per cent during the last six months of 1987. Concurrent declines of approximately 80 per cent in the prevalence of sexual behaviors associated with HIV transmission were also observed in the sample.     

How well do antenatal clinic (ANC) attendees represent the general population? A comparison of HIV prevalence from ANC sentinel surveillance sites with a population-based survey of women aged 15-49 in Cambodia

BACKGROUND: The purpose of this study was to evaluate whether HIV-1 prevalence among antenatal clinic (ANC) attendees in Cambodia provided a reasonable estimate of HIV-1 prevalence among all women 15-49 years. METHODS Antenatal clinic attendees in five HIV sentinel surveillance sites (five provinces) were selected by consecutive sampling (n = 1695). The population survey of females by household was carried out in the same five areas. Household females aged 15-49 years were selected using a three-stage cluster sampling design (n = 3066). Serum-based HIV ELISA testing was done for both ANC attendees and household females. The HIV prevalence for ANC attendees and household females were compared by age group and urban versus rural location. RESULTS: The overall prevalence of HIV-1 infection among ANC attendees (1.62%, 95% CI : 1.26-1.98) was similar to the overall prevalence obtained from the general population of household females (1.24%, 95% CI : 0.92-1.55) in the same catchment areas in Cambodia. In the rural areas, the overall HIV prevalence among ANC attendees (2.18%, 95% CI : 1.59-2.77) was significantly higher than among the household females (0.86%, 95% CI : 0.49-1.23) after adjustment for age distribution and education level. In the 15-24 age group in rural areas, the HIV prevalence of ANC women was 2.71% (95% CI : 0.96-4.46) compared with 0.77% (95% CI : 0.02-1.53) in household females. CONCLUSIONS: Although ANC data can be used to estimate trends over time, it should be realized that ANC data may overestimate the actual prevalence in the younger age group in rural areas in Cambodia.     

云南省德宏州2005-2010年未婚孕产妇艾滋病病毒感染及其影响因素分析

目的:了解云南省德宏州未婚孕产妇艾滋病流行趋势,探讨影响未婚孕产妇感染艾滋病病毒(HIV)的危险因素。方法:收集2005-2010年间进入德宏州各级医院和计划生育服务站就诊的未婚孕产妇的社会人口学、行为学和HIV感染信息,对HIV阳性者血清进行BED-捕获酶联免疫试验(BED-CEIA)以检测其是否系新近感染者。结果:德宏州2005-2010年间共调查12 742例未婚孕产妇,HIV感染率和新近感染率分别为0.71%和0.25%。2007年HIV感染率和新近感染率最高,分别为1.13%和0.86%。多因素logistic回归分析结果显示,缅甸籍(AOR:2.57;95%CI:1.13～5.84)未婚孕产妇HIV感染率较高,而高中/中专文化程度(AOR:0.19;95%CI:0.06～0.58)、"丈夫"/男朋友无吸毒史(AOR:0.18;95%CI:0.04～0.75)未婚孕产妇HIV感染率较低。结论:德宏州未婚孕产妇HIV感染率及新近感染率较高。缅甸籍、"丈夫"/男朋友吸毒史、文化水平低是导致未婚孕产妇感染HIV的高危因素。有必要加强未婚孕产妇人群艾滋病防控工作。     

The changing prevalence of neural tube defects: a population-based study in the north of England, 1984-96. Northern Congenital Abnormality Survey Steering Group

Using data from the Northern Congenital Abnormality Survey, we describe trends in the prevalence of neural tube defects (NTDs), maternal age-specific prevalence, outcome of pregnancy and the sensitivity of antenatal diagnosis of NTD-affected pregnancies in the Northern Region during 1984-96. This population-based sample consisted of 934 NTDs: there were 403 (43.1%) with anencephaly, 472 (50.5%) with spina bifida and 59 (6.3%) with encephalocele. The total prevalence at birth was 17.9 per 10,000 births and terminations (95% confidence interval [CI] = 16.7, 19.0) with a significant reduction over time (chi(2) for trend = 7.2; P = 0.007). The overall birth prevalence was 5.6 per 10,000 births [95% CI = 5.0, 6.3]; there was also a significant reduction in birth prevalence with time (chi(2) for trend = 68.3; P < 0.0001). Maternal age-specific prevalence rates decreased with increasing age. The proportion of NTD pregnancies terminated increased from 60.3% (325 cases) during 1984-90 to 78.6% (293 cases) during 1991-96, whereas the proportion of livebirths declined from 31.7% (171 cases) to 15.0% (56 cases) (P < 0.001). The sensitivity of antenatal diagnosis was consistently high for anencephaly (98%) and increased significantly for spina bifida from 60% during 1984-90 to 85% during 1991-96 (P < 0.05). Ascertainment of all cases of NTD in the Northern Region revealed a twofold reduction in birth prevalence between 1984-90 and 1991-96. This has resulted from improvements in the accuracy of antenatal detection of NTD-affected pregnancies with an increase in terminations of pregnancy.     

Screening prospective blood donors for AIDS risk factors: will sufficient donors be found?

Using data from various sources--we estimate that 14 to 19 per cent of American males 17-75 have personal histories that place them at high risk of transmitting the HIV infection while an additional 2 per cent of adult females may be similarly affected. Because roughly one fourth of either group may already be unsuited to give blood, we estimate that 10-14 per cent of adult males, and 1 per cent of females would be specifically deferred from giving blood because of personal histories of high-risk behavior. Local adjustments in the assumptions underlying these estimates are needed to apply them to given communities.     

Temporal and regional variation in hysterectomy rates in the United States, 1970--1975.

Regional hysterectomy rates in the United States for 1970 and 1975 have been estimated from a one per cent sample of hospital discharges. All rates have been corrected for the number of women truly at risk, that is, with uteri intact, and regional and age-specific estimates of uterine prevalence in 1975 are provided. The rates rose by one-third in 1970-1975, with the increase taking place nearly uniformly over all ages below 65 years. Rates were greatest for 40--44-year-old women, but in 1970 there was a secondary peak for women between the ages of 65 and 69 years. That peak disappeared with rising rates for younger women in 1975. For women under age 35 years, the hysterectomy rate in the South was three times higher than that in the Northeast.     

Age-specific back-projection of HIV diagnosis data

A method for reconstructing the HIV infection curve from data on both HIV and AIDS diagnoses is enhanced by using age as a covariate and by using the diagnosis data to estimate parameters that were previously assumed known. Maximum likelihood estimation is used for parameters of the induction distribution. Each of the set of parameters that specify the baseline rate of infection over time and the set of parameters giving the relative susceptibility over age are estimated by maximizing the likelihood subject to a smoothness requirement. We find that estimating the extra parameters is feasible, producing estimates with good precision. Including age as a covariate gives 90 per cent confidence intervals for the HIV incidence curve that are about 20 per cent narrower than those obtained when age data are not used.     

Estimating long-term trends in the incidence and prevalence of opiate use/injecting drug use and the number of former users: back-calculation methods and opiate overdose deaths

The authors explored an age-specific back-calculation approach to estimating long-term trends in the incidence and prevalence of opiate use/injecting drug use (IDU) in England for 1968-2000. The incidence of opiate use/IDU was estimated by combining information on the observed opiate overdose deaths of persons aged 15-44 years with knowledge on the distribution of the time between starting opiate use/IDU and death by overdose (incubation time distribution). The resulting incidence, together with the incubation time distribution, other drug-related mortality, and the general age-specific mortality rate, was then used to estimate the prevalence of current and former users. Provisional estimates suggested two major increases in incidence in the late 1970s and early 1990s, with models including information on age at death suggesting a recent decline since 1997 and that prevalence of opiate use/IDU increased substantially in the 1990s. Results were crucially dependent on assumptions about key parameters of the back-calculation framework. In theory, the approach is a valuable addition to the portfolio of indirect methods for estimating incidence and prevalence of dependent opiate use/IDU. In practice, its full potential will be realized only once better information on the process of stopping opiate use/IDU becomes available and more precise estimates of current and historical overdose mortality are obtained.