Alternatives for logistic regression in cross-sectional studies: an empirical comparison of models that directly estimate the prevalence ratio

BACKGROUND: Cross-sectional studies with binary outcomes analyzed by logistic regression are frequent in the epidemiological literature. However, the odds ratio can importantly overestimate the prevalence ratio, the measure of choice in these studies. Also, controlling for confounding is not equivalent for the two measures. In this paper we explore alternatives for modeling data of such studies with techniques that directly estimate the prevalence ratio. METHODS: We compared Cox regression with constant time at risk, Poisson regression and log-binomial regression against the standard Mantel-Haenszel estimators. Models with robust variance estimators in Cox and Poisson regressions and variance corrected by the scale parameter in Poisson regression were also evaluated. RESULTS: Three outcomes, from a cross-sectional study carried out in Pelotas, Brazil, with different levels of prevalence were explored: weight-for-age deficit (4%), asthma (31%) and mother in a paid job (52%). Unadjusted Cox/Poisson regression and Poisson regression with scale parameter adjusted by deviance performed worst in terms of interval estimates. Poisson regression with scale parameter adjusted by χ(2 )showed variable performance depending on the outcome prevalence. Cox/Poisson regression with robust variance, and log-binomial regression performed equally well when the model was correctly specified. CONCLUSIONS: Cox or Poisson regression with robust variance and log-binomial regression provide correct estimates and are a better alternative for the analysis of cross-sectional studies with binary outcomes than logistic regression, since the prevalence ratio is more interpretable and easier to communicate to non-specialists than the odds ratio. However, precautions are needed to avoid estimation problems in specific situations

Deaths and years of life lost due to suboptimal breast-feeding among children in the developing world: a global ecological risk assessment

Abstract Objective We estimate attributable fractions, deaths and years of life lost among infants and children ≤2 years of age due to suboptimal breast-feeding in developing countries. Design We compare actual practices to a minimum exposure pattern consisting of exclusive breast-feeding for infants ≤6 months of age and continued breast-feeding for older infants and children ≤2 years of age. For infants, we consider deaths due to diarrhoeal disease and lower respiratory tract infections, and deaths due to all causes are considered in the second year of life. Outcome measures are attributable fractions, deaths, years of life lost and offsetting deaths potentially caused by mother-to-child transmission of HIV through breast-feeding. Setting Developing countries. Subjects Infants and children ≤2 years of age. Results Attributable fractions for deaths due to diarrhoeal disease and lower respiratory tract infections are 55% and 53%, respectively, for the first six months of infancy, 20% and 18% for the second six months, and are 20% for all-cause deaths in the second year of life. Globally, as many as 1.45 million lives (117 million years of life) are lost due to suboptimal breast-feeding in developing countries. Offsetting deaths caused by mother-to-child transmission of HIV through breast-feeding could be as high as 242 000 (18.8 million years of life lost) if relevant World Health Organization recommendations are not followed. Conclusions The size of the gap between current practice and recommendations is striking when one considers breast-feeding involves no out-of-pocket costs, that there exists universal consensus on best practices, and that implementing current international recommendations could potentially save 1.45 million children's lives each yea

Socioeconomic inequalities in skilled birth attendance and child stunting in selected low and middle income countries: Wealth quintiles or deciles?

BACKGROUND: Wealth quintiles derived from household asset indices are routinely used for measuring socioeconomic inequalities in the health of women and children in low and middle-income countries. We explore whether the use of wealth deciles rather than quintiles may be advantageous. METHODS: We selected 46 countries with available national surveys carried out between 2003 and 2013 and with a sample size of at least 3000 children. The outcomes were prevalence of under-five stunting and delivery by a skilled birth attendant (SBA). Differences and ratios between extreme groups for deciles (D1 and D10) and quintiles (Q1 and Q5) were calculated, as well as two summary measures: the slope index of inequality (SII) and concentration index (CIX). RESULTS: In virtually all countries, stunting prevalence was highest among the poor, and there were larger differences between D1 and D10 than between Q1 and Q5. SBA coverage showed pro-rich patterns in all countries; in four countries the gap was greater than 80 pct points. With one exception, differences between extreme deciles were larger than between quintiles. Similar patterns emerged when using ratios instead of differences. The two summary measures provide very similar results for quintiles and deciles. Patterns of top or bottom inequality varied with national coverage levels. CONCLUSION: Researchers and policymakers should consider breakdowns by wealth deciles, when sample sizes allow. Use of deciles may contribute to advocacy efforts, monitoring inequalities over time, and targeting health interventions. Summary indices of inequalities were unaffected by the use of quintiles or deciles in their calculation

A Descriptive Review of the Methodologies Used in Household Surveys on Medicine Utilization

Background: Studies carried out in the community enable researchers to understand access to medicines, affordability, and barriers to use from the consumer's point of view, and may stimulate the development of adequate medicines policies. The aim of the present article was to describe methodological and analytical aspects of quantitative studies on medicine utilization carried out at the household level. Methods: Systematic review of original papers with data collected in studies in which the household was a sampling unit, published between 1995 and 2008. The electronic review was carried out in Medline/Pubmed, Scielo and Lilacs. The reference lists of the papers identified were examined, as well as other publications by their authors. Studies on the utilization of specific pharmacological groups, or those including only respondents with a given disease were excluded. Results: Out of 4852 papers initially identified in the literature search, 61 fulfilled our inclusion criteria. Most studies were carried out in Europe and North America and used a cross-sectional approach. More than 80% used face-to-face interviews for data collection, and the most frequently used recall period for assessing medicine utilization was 14–15 days. In 59% of the studies, interviewers were trained to request the packaging of the medicines reported by the subjects; medical prescriptions were requested less frequently (15% of the studies). Conclusion: These data will be useful for updating researchers on what methods their peers are currently using. Such information may help overcome challenges in the planning and analyses of future studies. Moreover, this publication may contribute to the improvement of the quality of medicine use data obtained in household surveys

Experiências de discriminação entre universitários do Rio de Janeiro

OBJECTIVE: To understand experiences of discrimination lived by undergraduate students and to analyze their applicability to the construction of a Brazilian discrimination scale. METHODOLOGICAL PROCEDURES: In a qualitative study five focus groups were conducted with 43 university students from the city of Rio de Janeiro, Southeastern Brazil, in 2008. Students from undergraduate courses with different candidate/place ratios; of both sexes; self-identified as white, mixed or black; and belonging to two public higher education institutions were selected. An interview guide focusing on issues related to "prejudice" and "discrimination" and asking participants about their experiences of discrimination was used. The method of interpretation of meanings was adopted, seeking to understand the context, reasons and logics of participants' speech. ANALYSIS OF RESULTS: Prejudice was interpreted as something belonging to the field of ideas, probably equivocated, and which could be either positive or negative. Discrimination was attributed to the field of observable behaviors and with an invariably negative connotation. The interpretation of a discriminatory event as such was influenced by subjective factors, such as personal interests and the level of affectivity established between individuals. However, the limit between what was interpreted as discriminatory or not depended strongly on the specific context in which the interaction among individuals occurred. Different situations and, at times, more than one motivation were simultaneously indicated as regards discriminatory experiences. Participants saw themselves as both victims and perpetrators of discrimination. CONCLUSIONS: The interpretation of an event as discriminatory involves great complexity and the experiences of discrimination can hardly be generalized. When evident, the reasons for which individuals suppose they have been discriminated against may be multiple and associated with each other. Such aspects must be considered when constructing items for the discrimination scale.OBJETIVO: Comprender las experiencias de discriminación vividas por jóvenes estudiantes y analizar su aplicación para construcción de una escala brasilera de discriminación. PROCEDIMIENTOS METODOLÓGICOS: Estudio cualitativo realizado con cinco grupos focales con 43 universitarios de Rio de Janeiro, Sureste de Brasil, en 2008. Fueron seleccionados estudiantes de cursos con distintas relaciones candidato/cupo, de ambos sexos y autoclasificados en las categorías de color/raza blanca, parda y negra de dos instituciones de enseñanza pública superior. Fue utilizado la guía que abarcaba los términos preconcepto y discriminación y cuestionaba los participantes acerca de sus experiencias discriminatorias. Se adoptó el método de interpretación de sentidos, buscándose aprender el contexto, las razones y las lógicas de las conversas de los sujetos. ANÁLISIS DE LOS RESULTADOS: El preconcepto fue interpretado como algo perteneciente al campo de las ideas y posiblemente equivocado, pudiendo ser tanto positivo como negativo. La discriminación fue atribuida al plano de los comportamientos observables y con connotación invariablemente negativa. La interpretación de un evento como discriminatorio fue influenciada por factores subjetivos, tales como los intereses particulares y el grado de afectividad establecido entre los individuos. Sin embargo, los limites entre lo que fue interpretado como discriminatorio o no dependió fuertemente del contexto específico en que ocurrió la interacción entre los sujetos. Diferentes escenarios y, eventualmente, más que una motivación fueron simultáneamente apuntadas para las experiencias discriminatorias. Los participantes se reconocieron tanto como víctimas como perpetradores de discriminación. CONCLUSIONES: La interpretación de un evento como discriminatorio posee gran complejidad y las experiencias de discriminación son difícilmente generalizables. Al ser evidentes, los motivos por los cuales los sujetos suponen que fueron discriminados pueden ser múltiples y estar asociados. Tales aspectos deben ser considerados en la construcción de escalas de discriminación.OBJETIVO: Compreender experiências de discriminação vividas por jovens universitários e analisar sua aplicação à construção de escala brasileira de discriminação. PROCEDIMENTOS METODOLÓGICOS: Estudo qualitativo realizado com cinco grupos focais com 43 universitários do Rio de Janeiro, RJ, em 2008. Foram selecionados estudantes de cursos com distintas relações candidato/vaga, de ambos os sexos e autoclassificados nas categorias de cor/raça branca, parda e preta de duas instituições de ensino público superior. Foi utilizado o roteiro que abrangia os termos preconceito e discriminação e questionava os participantes acerca de suas experiências discriminatórias. Adotou-se o método de interpretação de sentidos, buscando-se apreender o contexto, as razões e as lógicas das falas dos sujeitos. ANÁLISE DOS RESULTADOS: O preconceito foi interpretado como algo pertencente ao campo das idéias e possivelmente equivocado, podendo ser tanto positivo quanto negativo. A discriminação foi atribuída ao plano dos comportamentos observáveis e com conotação invariavelmente negativa. A interpretação de um evento como discriminatório foi influenciada por fatores subjetivos, tais como os interesses particulares e o grau de afetividade estabelecido entre os indivíduos. Porém, os limites entre o que foi interpretado como discriminatório ou não dependeu fortemente do contexto específico em que ocorreu a interação entre os sujeitos. Diferentes cenários e, eventualmente, mais do que uma motivação foram simultaneamente apontados nas experiências discriminatórias. Os participantes se reconheceram tanto como vítimas quanto perpetradores de discriminação. CONCLUSÕES: A interpretação de um evento como discriminatório é complexa e as experiências de discriminação são dificilmente generalizáveis. Quando evidentes, os motivos pelos quais os sujeitos supõem que foram discriminados podem ser múltiplos e estar associados. Tais aspectos devem ser considerados na construção de escalas de discriminação

Can mothers rely on the Brazilian health system for their deliveries? An assessment of use of the public system and out-of-pocket expenditure in the 2004 Pelotas Birth Cohort Study, Brazil

<p>Abstract</p> <p>Background</p> <p>In a country where comprehensive free health care is provided via a public health system (SUS), an unexpected high frequency of catastrophic out-of-pocket expenditure has been described. We studied how deliveries were financed among mothers of a birth cohort and whether they were an important source of household out-of-pocket expenditure.</p> <p>Methods</p> <p>All deliveries occurring in the city of Pelotas, Brazil, during 2004, were recruited for a birth cohort study. All mothers were interviewed just after birth and three months later. Comprehensive data on the pregnancy, delivery, birth conditions and newborn health were collected, along with detailed information on expenses related to the delivery.</p> <p>Results</p> <p>The majority of the deliveries (81%) were financed by the public health system, a proportion that increased to more than 95% among the 40% poorest mothers. Less than 1% of these mothers reported some out-of-pocket expenditure. Even among those mothers covered by a private health plan, nearly 50% of births were financed by the SUS. Among the 20% richest, a third of the deliveries were paid by the SUS, 50% by private health plans and 17% by direct payment.</p> <p>Conclusion</p> <p>The public health system offered services in quantity and quality enough to attract even beneficiaries of private health plans and spared mothers from the poorest strata of the population of practically any expense.</p

The double task of preventing malnutrition and overweight: a quasi-experimental community-based trial

Background: The Maternal-Child Pastoral is a volunteer-based community organization of the Dominican Republic that works with families to improve child survival and development. A program that promotes key practices of maternal and child care through meetings with pregnant women and home visits to promote child growth and development was designed and implemented. This study aims to evaluate the impact of the program on nutritional status indicators of children in the first two years of age. Methods: A quasi-experimental design was used, with groups paired according to a socioeconomic index, comparing eight geographical areas of intervention with eight control areas. The intervention was carried out by lay health volunteers. Mothers in the intervention areas received home visits each month and participated in a group activity held biweekly during pregnancy and monthly after birth. The primary outcomes were length and body mass index for age. Statistical analyses were based on linear and logistic regression models. Results: 196 children in the intervention group and 263 in the control group were evaluated. The intervention did not show statistically significant effects on length, but point estimates found were in the desired direction: mean difference 0.21 (95%CI −0.02; 0.44) for length-for-age Z-score and OR 0.50 (95%CI 0.22; 1.10) for stunting. Significant reductions of BMI-for-age Z-score (−0.31, 95%CI −0.49; -0.12) and of BMI-for-age > 85th percentile (0.43, 95%CI 0.23; 0.77) were observed. The intervention showed positive effects in some indicators of intermediary factors such as growth monitoring, health promotion activities, micronutrient supplementation, exclusive breastfeeding and complementary feeding. Conclusions: Despite finding effect measures pointing to effects in the desired direction related to malnutrition, we could only detect a reduction in the risk of overweight attributable to the intervention. The findings related to obesity prevention may be of interest in the context of the nutritional transition. Given the size of this study, the results are encouraging and we believe a larger study is warranted.The intervention and the impact assessment were carried out with financial support from the United Nations Children’s Fund (UNICEF), the Ministry of Public Health of the Dominican Republic, private donors from the Netherlands, and the partnership Action for Family Health (Catholic Medical Mission Board, Pan-American Health Organization (PAHO/WHO), Brystol-Myers Squibb Foundation). We also thank the Child’s Pastoral of Brazil for the support to learn and adapt their methods of intervention, the Graduate Program in Nutrition -Federal University of São Paulo- for their assistance in designing the intervention and the Graduate Program in Epidemiology -Federal University of Pelotas- for his key contributions in methodological aspects of the impact assessment. Special thanks to the families participating in the study, volunteers and professional staff of the Maternal-Child Pastoral, and all persons and institutions who contributed to this work