Showing papers in "International Journal of Epidemiology in 2010"

Cohort Profile: The China Health and Nutrition Survey—monitoring and understanding socio-economic and health change in China, 1989–2011

Abstract: This research journal article presents a detailed overview of a cohort profile of the China Health and Nutrition Survey (CHNS) which allows for the monitoring and understanding of socio-economic and health change in China from 1989-2011. The author discusses the history and development of the CHNS as a result of the countrys transformations since Chinas reform and open policy. The CHNS was established with the goal to develop a multipurpose longitudinal survey that would allow the research group to examine a series of economic sociological demographic and health questions. The article describes the design of the survey to include in-depth coverage at the individual household and community levels though it was not designed to be representative of China but to be randomly selected and capture a range of economic and demographic circumstances. It provides data randomly from eight different provinces and rounds have been completed nearly every three years since 1989. Though they are very complex to determine with the survey response rates and attrition are assessed along with descriptions of changes in lost-to-follow-up rates. The article describes key finds and publications to be numerous including links to obesity from occupation and transportation; nutrition and chronic disease; and important policy results for agriculture and poverty reduction programs. Lastly the author provides a summary of the CHNSs strengths and weaknesses and recommendations for accessing the data and further information.

Illustrating bias due to conditioning on a collider

Abstract: That conditioning on a common effect of exposure and outcome may cause selection, or collider-stratification, bias is not intuitive. We provide two hypothetical examples to convey concepts underlying bias due to conditioning on a collider. In the first example, fever is a common effect of influenza and consumption of a tainted egg-salad sandwich. In the second example, case-status is a common effect of a genotype and an environmental factor. In both examples, conditioning on the common effect imparts an association between two otherwise independent variables; we call this selection bias.

HIV transmission risk through anal intercourse: systematic review, meta-analysis and implications for HIV prevention

Abstract: Background The human immunodeficiency virus (HIV) infectiousness of anal intercourse (AI) has not been systematically reviewed, despite its role driving HIV epidemics among men who have sex with men (MSM) and its potential contribution to heterosexual spread. We assessed the per-act and per-partner HIV transmission risk from AI exposure for heterosexuals and MSM and its implications for HIV prevention. Methods Systematic review and meta-analysis of the literature on HIV-1 infectiousness through AI was conducted. PubMed was searched to September 2008. A binomial model explored the individual risk of HIV infection with and without highly active antiretroviral therapy (HAART). Results A total of 62 643 titles were searched; four publications reporting per-act and 12 reporting per-partner transmission estimates were included. Overall, random effects model summary estimates were 1.4% [95% confidence interval (CI) 0.2–2.5)] and 40.4% (95% CI 6.0–74.9) for per-act and per-partner unprotected receptive AI (URAI), respectively. There was no significant difference between per-act risks of URAI for heterosexuals and MSM. Per-partner unprotected insertive AI (UIAI) and combined URAI–UIAI risk were 21.7% (95% CI 0.2–43.3) and 39.9% (95% CI 22.5–57.4), respectively, with no available per-act estimates. Per-partner combined URAI–UIAI summary estimates, which adjusted for additional exposures other than AI with a ‘main’ partner [7.9% (95% CI 1.2–14.5)], were lower than crude (unadjusted) estimates [48.1% (95% CI 35.3–60.8)]. Our modelling demonstrated that it would require unreasonably low numbers of AI HIV exposures per partnership to reconcile the summary per-act and per-partner estimates, suggesting considerable variability in AI infectiousness between and within partnerships over time. AI may substantially increase HIV transmission risk even if the infected partner is receiving HAART; however, predictions are highly sensitive to infectiousness assumptions based on viral load. Conclusions Unprotected AI is a high-risk practice for HIV transmission, probably with substantial variation in infectiousness. The significant heterogeneity between infectiousness estimates means that pooled AI HIV transmission probabilities should be used with caution. Recent reported rises in AI among heterosexuals suggest a greater understanding of the role AI plays in heterosexual sex lives may be increasingly important for HIV prevention.

Water, sanitation and hygiene for the prevention of diarrhoea.

Abstract: Background Ever since John Snow’s intervention on the Broad St pump, the effect of water quality, hygiene and sanitation in preventing diarrhoea deaths has always been debated. The evidence identified in previous reviews is of variable quality, and mostly relates to morbidity rather than mortality. Methods We drew on three systematic reviews, two of them for the Cochrane Collaboration, focussed on the effect of handwashing with soap on diarrhoea, of water quality improvement and of excreta disposal, respectively. The estimated effect on diarrhoea mortality was determined by applying the rules adopted for this supplement, where appropriate. Results The striking effect of handwashing with soap is consistent across various study designs and pathogens, though it depends on access to water. The effect of water treatment appears similarly large, but is not found in few blinded studies, suggesting that it may be partly due to the placebo effect. There is very little rigorous evidence for the health benefit of sanitation; four intervention studies were eventually identified, though they were all quasi-randomized, had morbidity as the outcome, and were in Chinese. Conclusion We propose diarrhoea risk reductions of 48, 17 and 36%, associated respectively, with handwashing with soap, improved water quality and excreta disposal as the estimates of effect for the LiST model. Most of the evidence is of poor quality. More trials are needed, but the evidence is nonetheless strong enough to support the provision of water supply, sanitation and hygiene for all.

Brain tumour risk in relation to mobile telephone use: results of the INTERPHONE international case-control study

Abstract: Conclusions Overall, no increase in risk of glioma or meningioma was observed with use of mobile phones. There were suggestions of an increased risk of glioma at the highest exposure levels, but biases and error prevent a causal interpretation. The possible effects of long-term heavy use of mobile phones require further investigation.

The effects of waterpipe tobacco smoking on health outcomes: a systematic review

Abstract: Background There is a need for a comprehensive and critical review of the literature to inform scientific debates about the public health effects of waterpipe smoking. The objective of this study was therefore to systematically review the medical literature for the effects of waterpipe tobacco smoking on health outcomes. Methods We conducted a systematic review using the Cochrane Collaboration methodology for conducting systematic reviews. We rated the quality of evidence for each outcome using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology. Results Twenty-four studies were eligible for this review. Based on the available evidence, waterpipe tobacco smoking was significantly associated with lung cancer [odds ratio (OR) = 2.12; 95% confidence interval (CI) 1.32-3.42], respiratory illness (OR = 2.3; 95% CI 1.1-5.1), low birth-weight (OR = 2.12; 95% CI 1.08-4.18) and periodontal disease (OR = 3-5). It was not significantly associated with bladder cancer (OR = 0.8; 95% CI 0.2-4.0), nasopharyngeal cancer (OR = 0.49; 95% CI 0.20-1.23), oesophageal cancer (OR = 1.85; 95% CI 0.95-3.58), oral dysplasia (OR = 8.33; 95% CI 0.78-9.47) or infertility (OR = 2.5; 95% CI 1.0-6.3) but the CIs did not exclude important associations. Smoking waterpipe in groups was not significantly associated with hepatitis C infection (OR = 0.98; 95% CI 0.80-1.21). The quality of evidence for the different outcomes varied from very low to low. Conclusion Waterpipe tobacco smoking is possibly associated with a number of deleterious health outcomes. There is a need for high-quality studies to identify and quantify with confidence all the health effects of this form of smoking.

Thirty-five-year trends in cardiovascular risk factors in Finland

Abstract: Background In the late 1960s, coronary heart disease (CHD) mortality among Finnish men was the highest in the world. From 1972 to 2007, risk factor surveys have been carried out to monitor risk factor trends and assess their contribution to declining mortality in Finland. Methods The first risk factor survey was carried out in the North Karelia and Kuopio provinces in 1972 as the basis for the evaluation of the North Karelia Project. Since then, up to five geographical areas have been included in the surveys. The target population has been persons aged 25-74 years, except in the first two surveys where the sample was drawn from a population aged 30-59 years. Risk factor contribution on mortality change was assessed by a logistic regression model. Results A remarkable decline in serum cholesterol levels was observed between 1972 and 2007. Blood pressure declined among both men and women until 2002 but levelled off during the last 5 years. Prevalence of smoking decreased among men. Among women, smoking increased throughout the survey years until 2002 but did not increase between 2002 and 2007. Body mass index (BMI) has continuously increased among men. Among women, BMI decreased until 1982, but since then an increasing trend has been observed. Risk factor changes explained a 60% reduction in coronary mortality in middle-aged men while the observed reduction was 80%. Conclusions The 80% decline in coronary mortality in Finland mainly reflects a great reduction of the risk factor levels; these in turn have been associated with long-term comprehensive chronic disease prevention and health promotion interventions.

‘Kangaroo mother care’ to prevent neonatal deaths due to preterm birth complications

Abstract: Background ‘Kangaroo mother care’ (KMC) includes thermal care through continuous skin-to-skin contact, support for exclusive breastfeeding or other appropriate feeding, and early recognition/response to illness. Whilst increasingly accepted in both high- and low-income countries, a Cochrane review (2003) did not find evidence of KMC’s mortality benefit, and did not report neonatal-specific data. Objectives The objectives of this study were to review the evidence, and estimate the effect of KMC on neonatal mortality due to complications of preterm birth. Methods We conducted systematic reviews. Standardized abstraction tables were used and study quality assessed by adapted GRADE methodology. Meta-analyses were undertaken. Results We identified 15 studies reporting mortality and/or morbidity outcomes including nine randomized controlled trials (RCTs) and six observational studies all from low- or middle-income settings. Except one, all were hospital-based and included only babies of birth-weight <2000 g (assumed preterm). The one community-based trial had missing birthweight data, as well as other limitations and was excluded. Neonatal-specific data were supplied by two authors. Meta-analysis of three RCTs commencing KMC in the first week of life showed a significant reduction in neonatal mortality [relative risk (RR) 0.49, 95% confidence interval (CI) 0.29–0.82] compared with standard care. A meta-analysis of three observational studies also suggested significant mortality benefit (RR 0.68, 95% CI 0.58–0.79). Five RCTs suggested significant reductions in serious morbidity for babies <2000 g (RR 0.34, 95% CI 0.17–0.65). Conclusion This is the first published meta-analysis showing that KMC substantially reduces neonatal mortality amongst preterm babies (birth weight <2000 g) in hospital, and is highly effective in reducing severe morbidity, particularly from infection. However, KMC remains unavailable at-scale in most low-income countries.

Folic acid to reduce neonatal mortality from neural tube disorders

Abstract: Background Neural tube defects (NTDs) remain an important, preventable cause of mortality and morbidity. High-income countries have reported large reductions in NTDs associated with folic acid supplementation or fortification. The burden of NTDs in low-income countries and the effectiveness of folic acid fortification/supplementation are unclear. Objective To review the evidence for, and estimate the effect of, folic acid fortification/supplementation on neonatal mortality due to NTDs, especially in low-income countries. Methods We conducted systematic reviews, abstracted data meeting inclusion criteria and evaluated evidence quality using adapted Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology. Where appropriate, meta-analyses were performed. Results Meta-analysis of three randomized controlled trials (RCTs) of folic acid supplementation for women with a previous pregnancy with NTD indicates a 70% [95% confidence interval (CI): 35–86] reduction in recurrence (secondary prevention). For NTD primary prevention through folic acid supplementation, combining one RCT with three cohort studies which adjusted for confounding, suggested a reduction of 62% (95% CI: 49–71). A meta-analysis of eight population-based observational studies examining folic acid food fortification gave an estimated reduction in NTD incidence of 46% (95% CI: 37–54). In low-income countries an estimated 29% of neonatal deaths related to visible congenital abnormalities are attributed to NTD. Assuming that fortification reduces the incidence of NTDs, but does not alter severity or case-fatality rates, we estimate that folic acid fortification could prevent 13% of neonatal deaths currently attributed to congenital abnormalities in low-income countries. Discussion Scale-up of periconceptional supplementation programmes is challenging. Our final effect estimate was therefore based on folic acid fortification data. If folic acid food fortification achieved 100% population coverage the number of NTDs in low-income countries could be approximately halved. Conclusion The evidence supports both folic acid supplementation and fortification as effective in reducing neonatal mortality from NTDs.

Causal thinking and complex system approaches in epidemiology

Abstract: Identifying biological and behavioural causes of diseases has been one of the central concerns of epidemiology for the past half century. This has led to the development of increasingly sophisticated conceptual and analytical approaches focused on the isolation of single causes of disease states. However, the growing recognition that (i) factors at multiple levels, including biological, behavioural and group levels may influence health and disease, and (ii) that the interrelation among these factors often includes dynamic feedback and changes over time challenges this dominant epidemiological paradigm. Using obesity as an example, we discuss how the adoption of complex systems dynamic models allows us to take into account the causes of disease at multiple levels, reciprocal relations and interrelation between causes that characterize the causation of obesity. We also discuss some of the key difficulties that the discipline faces in incorporating these methods into non-infectious disease epidemiology. We conclude with a discussion of a potential way forward.

Sexual behaviours and the risk of head and neck cancers: a pooled analysis in the International Head and Neck Cancer Epidemiology (INHANCE) consortium

Abstract: Author(s): Heck, Julia E; Berthiller, Julien; Vaccarella, Salvatore; Winn, Deborah M; Smith, Elaine M; Shan'gina, Oxana; Schwartz, Stephen M; Purdue, Mark P; Pilarska, Agnieszka; Eluf-Neto, Jose; Menezes, Ana; McClean, Michael D; Matos, Elena; Koifman, Sergio; Kelsey, Karl T; Herrero, Rolando; Hayes, Richard B; Franceschi, Silvia; Wunsch-Filho, Victor; Fernandez, Leticia; Daudt, Alexander W; Curado, Maria Paula; Chen, Chu; Castellsague, Xavier; Ferro, Gilles; Brennan, Paul; Boffetta, Paolo; Hashibe, Mia | Abstract: BackgroundSexual contact may be the means by which head and neck cancer patients are exposed to human papillomavirus (HPV).MethodsWe undertook a pooled analysis of four population-based and four hospital-based case-control studies from the International Head and Neck Cancer Epidemiology (INHANCE) consortium, with participants from Argentina, Australia, Brazil, Canada, Cuba, India, Italy, Spain, Poland, Puerto Rico, Russia and the USA. The study included 5642 head and neck cancer cases and 6069 controls. We calculated odds ratios (ORs) of associations between cancer and specific sexual behaviours, including practice of oral sex, number of lifetime sexual partners and oral sex partners, age at sexual debut, a history of same-sex contact and a history of oral-anal contact. Findings were stratified by sex and disease subsite.ResultsCancer of the oropharynx was associated with having a history of six or more lifetime sexual partners [OR = 1.25, 95% confidence interval (CI) 1.01, 1.54] and four or more lifetime oral sex partners (OR = 2.25, 95% CI 1.42, 3.58). Cancer of the tonsil was associated with four or more lifetime oral sex partners (OR = 3.36, 95 % CI 1.32, 8.53), and, among men, with ever having oral sex (OR = 1.59, 95% CI 1.09, 2.33) and with an earlier age at sexual debut (OR = 2.36, 95% CI 1.37, 5.05). Cancer of the base of the tongue was associated with ever having oral sex among women (OR = 4.32, 95% CI 1.06, 17.6), having two sexual partners in comparison with only one (OR = 2.02, 95% CI 1.19, 3.46) and, among men, with a history of same-sex sexual contact (OR = 8.89, 95% CI 2.14, 36.8).ConclusionsSexual behaviours are associated with cancer risk at the head and neck cancer subsites that have previously been associated with HPV infection.

A consistent log-linear relationship between tuberculosis incidence and body mass index

Abstract: Background Low weight for height is an established risk factor for tuberculosis (TB), and recent studies suggest that overweight is a protective factor. No previous systematic review has been done to explore the consistency and establish the gradient of this apparent 'dose-response' relationship. Methods A systematic literature review was carried out to identify cohort studies that collected data on weight and height at baseline and that used a diagnosis of active TB as the study outcome. Weight-for-height measures used in the original studies were transformed into body mass index (BMI). Exponential trend lines were fitted to each data set. Results Six studies were included. In all of them, there was a log-linear inverse relationship between TB incidence and BMI, within the BMI range 18.5-30 kg/m(2). The average slope gave a reduction in TB incidence of 13.8% [95% confidence interval 13.4-14.2] per unit increase in BMI. The dose-response relationship was less certain at BMI 30 kg/m(2). Conclusion There is a strong and consistent log-linear relationship between TB incidence and BMI across a variety of settings with different levels of TB burden. More research is required to test the relationship at very low and very high BMI levels, to establish the biological mechanism linking BMI with risk of TB and to establish the potential impact on the global TB epidemic of changing nutritional status of populations.

The effect of oral rehydration solution and recommended home fluids on diarrhoea mortality

Abstract: Background Most diarrhoeal deaths can be prevented through the prevention and treatment of dehydration. Oral rehydration solution (ORS) and recommended home fluids (RHFs) have been recommended since 1970s and 1980s to prevent and treat diarrhoeal dehydration. We sought to estimate the effects of these interventions on diarrhoea mortality in children aged <5 years. Methods We conducted a systematic review to identify studies evaluating the efficacy and effectiveness of ORS and RHFs and abstracted study characteristics and outcome measures into standardized tables. We categorized the evidence by intervention and outcome, conducted meta-analyses for all outcomes with two or more data points and graded the quality of the evidence supporting each outcome. The CHERG Rules for Evidence Review were used to estimate the effectiveness of ORS and RHFs against diarrhoea mortality. Results We identified 205 papers for abstraction, of which 157 were included in the meta-analyses of ORS outcomes and 12 were included in the meta-analyses of RHF outcomes. We estimated that ORS may prevent 93% of diarrhoea deaths. Conclusions ORS is effective against diarrhoea mortality in home, community and facility settings; however, there is insufficient evidence to estimate the effectiveness of RHFs against diarrhoea mortality.

Rose's population strategy of prevention need not increase social inequalities in health

Abstract: Geoffrey Rose's 1985 paper, Sick individuals and sick populations, continues to spark debate and discussion. Since this original publication, there have been two notable challenges to Rose's population strategy of prevention. First, identification of high-risk individuals has improved considerably in accuracy, which some believe obviates the need for population-wide prevention strategies. Secondly, and more recently, it has been suggested that population strategies of prevention may inadvertently worsen social inequalities in health. We argue that population prevention will not necessarily worsen social inequalities in health, and the likelihood of it doing so will depend on whether the prevention strategy is more structural (targets conditions in which behaviours occur) or agentic (targets behaviour change among individuals) in nature. Also, there are potential drawbacks of approaches that focus on discrete populations (i.e. high risk or vulnerable) that need to be considered when selecting a strategy. Although Rose's ideas need to be continually scrutinized, his population strategy of prevention still holds considerable merit for improving population health and narrowing social inequalities in health.

Intelligence and education: causal perceptions drive analytic processes and therefore conclusions

Abstract: Background Educational attainment is associated with many life outcomes, including income, occupation and many health and lifestyle variables. Many researchers use it as a control variable in epidemiological and other social scientific studies, often without specifying exactly what environmental effects or set of personal characteristics is being controlled. Other researchers assume that genetically influenced intelligence drives educational attainment, and think that intelligence is the appropriate control variable. Researchers' different and often unstated causal assumptions can lead to very different analytical approaches and thus to very different results and interpretations. Methods, results and conclusions We document several examples of this important variation in the treatment of education and intelligence and their association. We recommend greater clarity in stating underlying assumptions and developing analytical approaches and greater objectivity in interpreting results. We discuss implications for study designs.

SITAR—a useful instrument for growth curve analysis

Abstract: Background Growth curve analysis is a statistical issue in life course epidemiology. Height in puberty involves a growth spurt, the timing and intensity of which varies between individuals. Such data can be summarized with individual Preece–Baines (PB) curves, and their five parameters then related to earlier exposures or later outcomes. But it involves fitting many curves. Methods We present an alternative SuperImposition by Translation And Rotation (SITAR) model, a shape invariant model with a single fitted curve. Curves for individuals are matched to the mean curve by shifting their curve up–down (representing differences in mean size) and left–right (for differences in growth tempo), and the age scale is also shrunk or stretched to indicate how fast time passes in the individual (i.e. velocity). These three parameters per individual are estimated as random effects while fitting the curve. The outcome is a mean curve plus triplets of parameters per individual (size, tempo and velocity) that summarize the individual growth patterns. The data are heights for Christ’s Hospital School (CHS) boys aged 9–19 years (N = 3245, n = 129 508), and girls with Turner syndrome (TS) aged 9–18 years from the UK Turner Study (N = 105, n = 1321). Results The SITAR model explained 99% of the variance in both datasets [residual standard deviation (RSD) 6–7 mm], matching the fit of individually-fitted PB curves. In CHS, growth tempo was associated with insulin-like growth factor-1 measured 50 years later (P = 0.01, N = 1009). For the girls with TS randomized to receive oxandrolone from 9 years, velocity was substantially increased compared with placebo (P = 10−8). Conclusions The SITAR growth curve model is a useful epidemiological instrument for the analysis of height in puberty.

Cessation of alcohol drinking, tobacco smoking and the reversal of head and neck cancer risk

Abstract: Background Quitting tobacco or alcohol use has been reported to reduce the head and neck cancer risk in previous studies. However, it is unclear how many years must pass following cessation of these habits before the risk is reduced, and whether the risk ultimately declines to the level of never smokers or never drinkers. Methods We pooled individual-level data from case–control studies in the International Head and Neck Cancer Epidemiology Consortium. Data were available from 13 studies on drinking cessation (9167 cases and 12 593 controls), and from 17 studies on smoking cessation (12 040 cases and 16 884 controls). We estimated the effect of quitting smoking and drinking on the risk of head and neck cancer and its subsites, by calculating odds ratios (ORs) using logistic regression models. Results Quitting tobacco smoking for 1–4 years resulted in a head and neck cancer risk reduction [OR 0.70, confidence interval (CI) 0.61–0.81 compared with current smoking], with the risk reduction due to smoking cessation after ≥20 years (OR 0.23, CI 0.18–0.31), reaching the level of never smokers. For alcohol use, a beneficial effect on the risk of head and neck cancer was only observed after ≥20 years of quitting (OR 0.60, CI 0.40–0.89 compared with current drinking), reaching the level of never drinkers. Conclusions Our results support that cessation of tobacco smoking and cessation of alcohol drinking protect against the development of head and neck cancer.

Socio-economic inequalities in breast and cervical cancer screening practices in Europe: influence of the type of screening program

Abstract: Background The aim of this study was to describe inequalities in the use of breast and cervical cancer screening services according to educational level in European countries in 2002, and to determine the influence of the type of screening program on the extent of inequality. Methods A cross-sectional study was performed using individual-level data from the WHO World Health Survey (2002) and data regarding the implementation of cancer screening programmes. The study population consisted of women from 22 European countries, aged 25-69 years for cervical cancer screening (n =11 770) and 50-69 years for breast cancer screening (n = 4784). Dependent variables were having had a PAP smear and having had a mammography during the previous 3 years. The main independent variables were socio-economic position (SEP) and the type of screening program in the country. For each country the prevalence of screening was calculated, overall and for each level of education, and indices of relative (RII) and absolute (SII) inequality were computed by educational level. Multilevel logistic regression models were fitted. Results SEP inequalities in screening were found in countries with opportunistic screening [comparing highest with lowest educational level: RII = 1.28, 95% confidence interval (CI) 1.12-1.48 for cervical cancer; and RII = 3.11, 95% CI 1.78-5.42 for breast cancer] but not in countries with nationwide population-based programmes. Inequalities were also observed in countries with regional screening programs (RII = 1.35, 95% CI 1.10-1.65 for cervical cancer; and RII = 1.58, 95% CI 1.26-1.98 for breast cancer). Conclusions Inequalities in the use of cancer screening according to SEP are higher in countries without population-based cancer screening programmes. These results highlight the potential benefits of population-based screening programmes.

Cohort Profile: The Golestan Cohort Study—a prospective study of oesophageal cancer in northern Iran

Abstract: The earliest reports of high incidence of oesophageal cancer (OC) in the northern parts of Iran date back to the early 1970s. A population-based cancer registry was established in 1969 as a joint effort between Tehran University and the International Agency for Research on Cancer (IARC). This registry confirmed the high incidence of OC in the eastern portion of the Caspian Sea littoral, in the area that is now known as Golestan Province. The highest incidence rates were reported from the semi-desert plain settled mainly by people of Turkmen ethnicity in Gonbad and Kalaleh counties, with estimated incidence rates of 109/10 among men and 174/10 among women (adjusted to the 1970 World Standard Population). The registry also showed low incidence of OC in the nearby Gilan province, 300 km to the west of Golestan, with incidence rates of 15/10 and 5.5/10 among men and women, respectively. A series of studies were conducted in the region in the 1970s, but they were not conclusive in explaining the

Tetanus toxoid immunization to reduce mortality from neonatal tetanus

Abstract: BACKGROUND: Neonatal tetanus remains an important and preventable cause of neonatal mortality globally. Large reductions in neonatal tetanus deaths have been reported following major increases in the coverage of tetanus toxoid immunization, yet the level of evidence for the mortality effect of tetanus toxoid immunization is surprisingly weak with only two trials considered in a Cochrane review. OBJECTIVE: To review the evidence for and estimate the effect on neonatal tetanus mortality of immunization with tetanus toxoid of pregnant women, or women of childbearing age. METHODS: We conducted a systematic review of multiple databases. Standardized abstraction forms were used. Individual study quality and the overall quality of evidence were assessed using an adaptation of the GRADE approach. Meta-analyses were performed. RESULTS: Only one randomised controlled trial (RCT) and one well-controlled cohort study were identified, which met inclusion criteria for meta-analysis. Immunization of pregnant women or women of childbearing age with at least two doses of tetanus toxoid is estimated to reduce mortality from neonatal tetanus by 94% [95% confidence interval (CI) 80-98%]. Additionally, another RCT with a case definition based on day of death, 3 case-control studies and 1 before-and-after study gave consistent results. Based on the consistency of the mortality data, the very large effect size and that the data are all from low/middle-income countries, the overall quality of the evidence was judged to be moderate. CONCLUSION: This review uses a standard approach to provide a transparent estimate of the high impact of tetanus toxoid immunization on neonatal tetanus.

Cohort Profile: Research on Osteoarthritis/Osteoporosis Against Disability study

Abstract: Since the proportion of the ageing population in Japan is increasing, a comprehensive and evidencebased strategy is urgently required for the prevention of musculoskeletal diseases, including osteoarthritis (OA) and osteoporosis (OP), both of which affect the activities of daily living (ADL) and quality of life (QOL) and increase morbidity and mortality. However, few prospective, longitudinal studies for the purpose of developing such a strategy have been conducted, and little information is available regarding the prevalence and incidence of musculoskeletal disorders, including OA and OP, as well as pain and disability in the Japanese population. It is difficult to design rational clinical and public health approaches for the diagnosis, evaluation and prevention of OA and OP without such epidemiological data. The Research on Osteoarthritis/osteoporosis Against Disability (ROAD) study was established in 2005 by N.Y., T.A., H.O., S.M., H.K. and K.N. (principal investigators). The principal investigators are affiliated with the 22nd Century Medical and Research Center, University of Tokyo.

Measuring cancer survival in populations: relative survival vs cancer-specific survival

Abstract: Background Two main methods of quantifying cancer patient survival are generally used: cancer-specific survival and relative survival. Both techniques are used to estimate survival in a single population, or to estimate differences in survival between populations. Arguments have been made that the relative survival approach is the only valid choice for population-based cancer survival studies because cancer-specific survival estimates may be invalid if there is misclassification of the cause of death. However, there has been little discussion, or evidence, as to how strong such biases may be, or of the potential biases that may result using relative survival techniques, particularly bias arising from the requirement for an external comparison group. Methods In this article we investigate the assumptions underlying both methods of survival analysis. We provide simulations relating to the impact of misclassification of death and non-comparability of expected survival for cause-specific and relative survival approaches, respectively. Results For cause-specific analyses, bias through misclassification of cause of death resulted in error in descriptive analyses particularly of cancers with moderate or poor survival, but had smaller impact in analyses involving group comparisons. Relative survival ratio (RSR) estimations were robust in relation to non-comparability of comparison populations for single RSR but were less so in group comparisons where there was large variation in survival. Conclusions Both cause-specific survival and relative survival are potentially valid epidemiological methods in population-based cancer survival studies, and the choice of method is dependent on the likely magnitude and direction of the biases in the specific analyses to be conducted.

Zinc for the treatment of diarrhoea: effect on diarrhoea morbidity, mortality and incidence of future episodes

Abstract: Background Zinc supplementation for the treatment of diarrhoea has been shown to decrease the duration and severity of the diarrhoeal episode, diarrhoea hospitalization rates and, in some studies, all-cause mortality. Using multiple outcome measures, we sought to estimate the effect of zinc for the treatment of diarrhoea on diarrhoea mortality and subsequent pneumonia mortality. Methods We conducted a systematic review of efficacy and effectiveness studies. We used a standardized abstraction and grading format and performed meta-analyses for all outcomes with ≥2 data points. The estimated effect on diarrhoea mortality was determined by applying the standard Child Health Epidemiology Reference Group rules for multiple outcomes. Results We identified 13 studies for abstraction. Zinc supplementation decreased the proportion of diarrhoeal episodes which lasted beyond 7 days, risk of hospitalization, all-cause mortality and diarrhoea mortality. Using diarrhoea hospitalizations as the closest and most conservative possible proxy for diarrhoea mortality, zinc for the treatment of diarrhoea is estimated to decrease diarrhoea mortality by 23%. Conclusion Zinc is an effective therapy for diarrhoea and will decrease diarrhoea morbidity and mortality when introduced and scaled-up in low-income countries.

Standards for CHERG reviews of intervention effects on child survival.

Abstract: BACKGROUND: The Lives Saved Tool (LiST) uses estimates of the effects of interventions on cause-specific child mortality as a basis for generating projections of child lives that could be saved by increasing coverage of effective interventions. Estimates of intervention effects are an essential element of LiST, and need to reflect the best available scientific evidence. This article describes the guidelines developed by the Child Health Epidemiology Reference Group (CHERG) that are applied by scientists conducting reviews of intervention effects for use in LiST. METHODS: The guidelines build on and extend those developed by the Cochrane Collaboration and the Working Group for Grading of Recommendations Assessment, Development and Evaluation (GRADE). They reflect the experience gained by the CHERG intervention review groups in conducting the reviews published in this volume, and will continue to be refined through future reviews. Presentation of the guidelines Expected products and guidelines are described for six steps in the CHERG intervention review process: (i) defining the scope of the review; (ii) conducting the literature search; (iii) extracting information from individual studies; (iv) assessing and summarizing the evidence; (v) translating the evidence into estimates of intervention effects and (vi) presenting the results. CONCLUSIONS: The CHERG intervention reviews represent an ambitious effort to summarize existing evidence and use it as the basis for supporting sound public health decision making through LiST. These efforts will continue, and a similar process is now under way to assess intervention effects for reducing maternal mortality.

Comparative appraisal of educational inequalities in overweight and obesity among adults in 19 European countries

Abstract: Background In Western societies, a lower educational level is often associated with a higher prevalence of overweight and obesity. However, there may be important international differences in the strength and direction of this relationship, perhaps in respect of differing levels of socio-economic development. We aimed to describe educational inequalities in overweight and obesity across Europe, and to explore the contribution of level of socio-economic development to cross-national differences in educational inequalities in overweight and obese adults in Europe. Methods Cross-sectional data, based on self-reports, were derived from national health interview surveys from 19 European countries (N = 127 018; age range = 25–44 years). Height and weight data were used to calculate the body mass index (BMI). Multivariate regression analysis was employed to measure educational inequalities in overweight and obesity, based on BMI. Gross domestic product (GDP) per capita was used as a measure of level of socio-economic development. Results Inverse educational gradients in overweight and obesity (i.e. higher education, less overweight and obesity) are a generalized phenomenon among European men and even more so among women. Baltic and eastern European men were the exceptions, with weak positive associations between education and overweight and obesity. Educational inequalities in overweight and obesity were largest in Mediterranean women. A 10 000-euro increase in GDP was related to a 3% increase in overweight and obesity for low-educated men, but a 4% decrease for high-educated men. No associations with GDP were observed for women. Conclusion In most European countries, people of lower educational attainment are now most likely to be overweight or obese. An increasing level of socio-economic development was associated with an emergence of inequalities among men, and a persistence of these inequalities among women.

How to assess the external validity of therapeutic trials: a conceptual approach

Abstract: Background External validity of study results is an important issue from a clinical point of view. From a methodological point of view, however, the concept of external validity is more complex than it seems to be at first glance. Methods Methodological review to address the concept of external validity. Results External validity refers to the question whether results are generalizable to persons other than the population in the original study. The only formal way to establish the external validity would be to repeat the study for that specific target population. We propose a three-way approach for assessing the external validity for specified target populations. (i) The study population might not be representative for the eligibility criteria that were intended. It should be addressed whether the study population differs from the intended source population with respect to characteristics that influence outcome. (ii) The target population will, by definition, differ from the study population with respect to geographical, temporal and ethnical conditions. Pondering external validity means asking the question whether these differences may influence study results. (iii) It should be assessed whether the study's conclusions can be generalized to target populations that do not meet all the eligibility criteria. Conclusion Judging the external validity of study results cannot be done by applying given eligibility criteria to a single target population. Rather, it is a complex reflection in which prior knowledge, statistical considerations, biological plausibility and eligibility criteria all have place.

Protective efficacy of interventions for preventing malaria mortality in children in Plasmodium falciparum endemic areas

Abstract: Background Insecticide-treated mosquito nets (ITNs) and indoor-residual spraying (IRS) are recommended strategies for preventing malaria in children. While their impact on all-cause child mortality is well documented, their impact on reducing malaria-attributable mortality has not been quantified. While the impact of intermittent preventive therapy in pregnant women (IPTp) and ITNs in pregnancy for improving birth outcomes is also well established, their impact on preventing neonatal or child mortality has not been quantified. Methods We performed two systematic literature reviews in Plasmodium falciparum endemic settings; one to estimate the effect of ITNs and IRS on preventing malaria-attributable mortality in children 1–59 months, and another to estimate the effect of ITNs and IPTp on preventing neonatal and child mortality through improvements in birth outcomes. Results We estimate the protective efficacy (PE) of ITNs and IRS on reducing malaria-attributable mortality 1–59 months to be 55%, with a range of 49–61%, in P. falciparum settings. We estimate malaria prevention interventions in pregnancy (IPTp and ITNs) to have a pooled PE of 35% (95% confidence interval: 23–45%) on reducing the prevalence of low birth weight (LBW) in the first or second pregnancy in areas of stable P. falciparum transmission. Conclusion This systematic review quantifies the PE of ITNs for reducing malaria-attributable mortality in children, and the PE of IPTp and ITNs during pregnancy for reducing LBW. It is assumed the impact of IRS is equal to that of ITNs on reducing malaria-attributable mortality in children. These data will be used in the Lives Saved Tool (LiST) model for estimating the impact of malaria prevention interventions. These data support the continued scale-up of these malaria prevention interventions in endemic settings that will prevent a considerable number of child deaths due directly and indirectly to malaria.

Cohort Profile: The EPIC-NL study

Abstract: A major scientific challenge for the next few decades is to understand the interaction between genetic susceptibility and environmental factors in the aetiology of chronic diseases. The most promising approach to discover these interactions requires a combined effort of epidemiology and molecular genetics and large sample sizes for sufficient power. Already in the early 90s, the European Prospective Investigation Into Cancer and Nutrition (EPIC) was initiated in 10 European countries to create a large cohort to study the aetiology of chronic diseases. The Netherlands has contributed two cohort studies to EPIC: the Prospect cohort of 17 357 women of the Julius Center in Utrecht, and the Monitoring Project on Risk Factors for Chronic Diseases (MORGEN) cohort of 22 654 men and women of the National Institute for Public Health and the Environment (RIVM) in Bilthoven. In the design phase, both cohorts collaborated closely to obtain maximal synergy in the design of the questionnaires and to follow identical protocols in the collection of biological samples. Because of the efficiency gain in maintaining the cohort infrastructure and in conducting scientific analyses, the Julius Center and the RIVM decided to combine efforts to maintain and expand the cohorts and biobanks by merging them into one EPICNetherlands (EPIC-NL) study.

Male circumcision for preventing heterosexual acquisition of HIV in men

Abstract: BACKGROUND The findings from observational studies, reviews and meta-analyses, supported by biological theories, that circumcised men appear less likely to acquire human immunodeficiency virus (HIV) has contributed to the recent ground swell of support for considering male circumcision as a strategy for preventing sexually acquired infection. We sought to elucidate and appraise the global evidence from published and unpublished studies that circumcision can be used as an intervention to prevent HIV infection. OBJECTIVES 1) To assess the evidence of an interventional effect of male circumcision for preventing acquisition of HIV-1 and HIV-2 by men through heterosexual intercourse 2) To examine the feasibility and value of performing individual person data (IPD) meta-analysis SEARCH STRATEGY We searched online for published and unpublished studies in The Cochrane Library (issue 2, 2002), MEDLINE (April 2002), EMBASE (February 2002) and AIDSLINE (August 2001). We also searched databases listing conference abstracts, scanned reference lists of articles and contacted authors of included studies. SELECTION CRITERIA We searched for randomized and quasi-randomized controlled trials of male circumcision or, in their absence, observational studies that compare acquisition rates of HIV-1 and HIV-2 infection in circumcised and uncircumcised heterosexual men. DATA COLLECTION AND ANALYSIS Independent reviewers selected studies, assessed study quality and extracted data. We stratified studies based on study design and on whether they included participants from the general population or high-risk groups (such as patients treated for sexually transmitted infections). We expressed findings as crude and adjusted odds ratios (OR) together with their 95% confidence intervals (CI) and conducted a sensitivity analysis to explore the effect of adjustment on study results. We investigated whether the method of circumcision ascertainment influenced study outcomes. MAIN RESULTS We identified no completed randomized controlled trials. Three randomized controlled trials are currently underway or commencing shortly. We found 34 observational studies: 16 conducted in the general population and 18 in high-risk populations. It seems unlikely that potential confounding factors were completely accounted for in any of the included studies. In particular, important risk factors, such as religion and sexual practices, were not adequately accounted for in many of the included studies. General population study results:The single cohort study (N = 5516) showed a significant difference in HIV transmission rates between circumcised and uncircumcised men [OR = 0.58; 95% CI: 0.36 to 0.96]. Results for the 14 cross-sectional studies were inconsistent, with point estimates for unadjusted odds ratios varying between 0.28 and 1.73. Six studies had statistically significant results, four in the direction of benefit and two in the direction of harm. The test for heterogeneity between the cross-sectional studies was highly significant (chi-square = 77.59; df = 13; P-value < 0.00001). Nine studies reported adjusted odds ratios with eight in the direction of benefit, ranging from 0.26 to 0.80. Use of adjusted results tended to show stronger evidence of an association although they remained heterogenous (chi-square = 75.2; df = 13; P-value < 0.00001). Only one case-control study was found (N = 51) which had a non-significant result [OR = 1.90; 95% CI: 0.50 to 7.20]. High-risk group study results:The four cohort studies identified found a protective effect from circumcision with point estimates for unadjusted odds ratios varying from 0.10 to 0.39. Two of these studies had statistically significant results. Two studies reported adjusted odds ratios, both protective with one being significant. The chi-square test for between-study heterogeneity was not significant (chi-square = 5.21; df = 3; P-value = 0.16). All eleven cross-sectional studies reporting unadjusted results found benefit from circumcision, eight of which had statistically significant results. Estimates of effnal studies reporting unadjusted results found benefit from circumcision, eight of which had statistically significant results. Estimates of effect varied from an unadjusted odds ratio of 0.10 to 0.66. Between-study heterogeneity was significant with the chi-square = 29.77; df = 10; P-value = 0.0009. Four of these studies reported adjusted odds ratios ranging from 0.20 to 0.59 and all were significant. One additional cross-sectional study only reported an adjusted odds ratio in the direction of benefit which was statistically significant. All three case-control studies found a protective effect of circumcision on HIV status, two being statistically significant. Point estimates varied from unadjusted odds ratios of 0.37 to 0.88. One reported an adjusted odds ratio showing a significant protective effect. Adverse effects:No studies reported on the adverse effects of circumcision. In most studies, circumcision had taken place during childhood or adolescence before the studies commenced. REVIEWER'S CONCLUSIONS We found insufficient evidence to support an interventional effect of male circumcision on HIV acquisition in heterosexual men. The results from existing observational studies show a strong epidemiological association between male circumcision and prevention of HIV, especially among high-risk groups. However, observational studies are inherently limited by confounding which is unlikely to be fully adjusted for. In the light of forthcoming results from RCTs, the value of IPD analysis of the included studies is doubtful. The results of these trials will need to be carefully considered before circumcision is implemented as a public health intervention for prevention of sexually transmitted HIV.