Discover the most talked about and latest scientific content & concepts.

Concept: Statistical data types


Research on poverty in the United States has largely consisted of examining cross-sectional levels of absolute poverty. In this analysis, we focus on understanding relative poverty within a life course context. Specifically, we analyze the likelihood of individuals falling below the 20th percentile and the 10th percentile of the income distribution between the ages of 25 and 60. A series of life tables are constructed using the nationally representative Panel Study of Income Dynamics data set. This includes panel data from 1968 through 2011. Results indicate that the prevalence of relative poverty is quite high. Consequently, between the ages of 25 to 60, 61.8 percent of the population will experience a year below the 20th percentile, and 42.1 percent will experience a year below the 10th percentile. Characteristics associated with experiencing these levels of poverty include those who are younger, nonwhite, female, not married, with 12 years or less of education, or who have a work disability.

Concepts: United States, German Socio-Economic Panel, Econometrics, Statistical data types, Cross-sectional data, Poverty threshold, Panel data, Panel Study of Income Dynamics


Early initiation of anti-retroviral treatment (ART) decreases mortality as compared to deferred treatment, but whether it preserves immune cells from early loss or promotes their recovery remains undefined. Determination of complex immunological endpoints in infants is often marred by missing data due to missed visits and/or inadequate sampling. Specialized methods are required to address missingness and facilitate data analysis.

Concepts: Immunity, Missing values, Statistical data types, Antibody, Immunology, Data, Immune system, Data analysis


Controversial results of the association between coffee consumption and bladder cancer (BC) risk were reported among epidemiological studies. Therefore, we conducted this meta-analysis to clarify the association. Relevant studies were identified according to the inclusion criteria. Totally, 34 case-control studies and 6 cohort studies were included in our meta-analysis. The overall odds ratio (OR) with 95% confidence interval (CI) between coffee consumption and BC risk was 1.33 (95% CI 1.19 to 1.48). The summary ORs of BC for an increase of 1 cup of coffee per day were 1.05 (95% CI 1.03 to 1.06) for case-control studies and 1.03 (95% CI 0.99 to 1.06) for cohort studies. The overall ORs for male coffee drinkers, female coffee drinkers and coffee drinkers of both gender were 1.31 (95% CI: 1.08 to 1.59), 1.30 (95% CI: 0.87 to 1.96) and 1.35 (95% CI: 1.20 to 1.51). Compared with smokers (OR = 1.24, 95% CI: 0.91 to 1.70), non-smokers had a higher risk (OR = 1.72, 95% CI: 1.25 to 2.35) for BC. Results of this meta-analysis suggested that there was an increased risk between coffee consumption and BC. Male coffee drinkers and non-smoking coffee drinkers were more likely to develop BC.

Concepts: Statistical terminology, Statistical data types, Male, Gender, Relative risk, Study design, Experimental design, Epidemiology


Large-scale prospective cohort studies are invaluable in epidemiology, but they are increasingly difficult and costly to establish and follow-up. More efficient methods for recruitment, data collection and follow-up are essential if such studies are to remain feasible with limited public and research funds. Here, we discuss how these challenges were addressed in the UK COSMOS cohort study where fixed budget and limited time frame necessitated new approaches to consent and recruitment between 2009-2012. Web-based e-consent and data collection should be considered in large scale observational studies, as they offer a streamlined experience which benefits both participants and researchers and save costs. Commercial providers of register and marketing data, smartphones, apps, email, social media, and the internet offer innovative possibilities for identifying, recruiting and following up cohorts. Using examples from UK COSMOS, this article sets out the dos and don'ts for today’s cohort studies and provides a guide on how best to take advantage of new technologies and innovative methods to simplify logistics and minimise costs. Thus a more streamlined experience to the benefit of both research participants and researchers becomes achievable.

Concepts: Statistical data types, Cohort, Research methods, Epidemiology, Cohort study, Scientific method, 21st century, Experimental design


BACKGROUND: Research on the role of diet in the prevention of depression is scarce. Some evidence suggests that depression shares common mechanisms with cardiovascular disease. DISCUSSION: Before considering the role of diet in the prevention of depression, several points need to be considered. First, in general, evidence has been found for the effects of isolated nutrients or foods, and not for dietary patterns. Second, most previous studies have a cross-sectional design. Third, information is generally collected though questionnaires, increasing the risk of misclassification bias. Fourth, adequate control of confounding factors in observational studies is mandatory. SUMMARY: Only a few cohort studies have analyzed the relationship between overall dietary patterns, such as the Mediterranean diet, and primary prevention of depression. They have found similar results to those obtained for the role of this dietary pattern in cardiovascular disease. To confirm the findings obtained in these initial cohort studies, we need further observational longitudinal studies with improved methodology, as well as large randomized primary prevention trials, with interventions based on changes in the overall food pattern, that include participants at high risk of mental disorders.

Concepts: Nutrition, Statistical data types, Cross-sectional study, Cohort study, Research methods, Epidemiology, Experimental design, Longitudinal study


The availability of longitudinal data collected prospectively from 1998 to 2011 at federally funded United States hemophilia treatment centers (U.S. HTCs) provided an opportunity to construct a descriptive analysis of how outcomes of men with severe hemophilia have been altered by the incremental advances and setbacks in hemophilia care in the last 50 years in the U.S. This surveillance collaboration with the U.S. Centers for Disease Control and Prevention assembled the largest uniformly examined population with severe hemophilia (n = 4,899 men with severe factor VIII and IX deficiency). To address the heterogeneity of this population, four successive birth cohorts, differentially affected by “eras” of hemophilia care, were examined separately in regards to demographics, complications of hemophilia and its treatment, and mortality. Severely affected men in each birth cohort were compared also to the corresponding mild hemophilia birth cohorts (n = 2587 men total) to control for outcomes that might be attributable to aging and environment independent of severely defective hemostasis. The analysis demonstrates improving access to standard of care therapy, correlating the proportion of men on prophylactic factor replacement and reduced bleeding frequency for the youngest men. Frequent bleeding persisted in one third to one half of men across all ages, however, and the disability gap between severe and mild hemophilia did not narrow. The greatest cause of death was liver failure but attempted anti-hepatitis C virus therapy and cure were low. The study suggests a continued need for national surveillance to monitor and inform hemophilia interventions and outcomes.

Concepts: Statistical data types, Experimental design, Research methods, Epidemiology, Demography, United States, Longitudinal study, Cohort study


The goal of the International Journal of Behavioral Nutrition and Physical Activity (IJBNPA) is to be the leading diet and physical activity journal. To achieve this aim we embrace and publish a number of different research designs from small, but in depth, qualitative studies to large scale cohort studies. IJBNPA prioritises research based on randomised controlled trials (RCTs), systematic reviews (with or without meta-analyses, as appropriate), and well conducted observational studies that expand knowledge and understanding of the area. IJBNPA will also consider and publish other study designs that are of sufficient quality such as strong or ground-breaking methodological papers, rigorous qualitative studies, debate papers and commentaries. However, due to the demands on the journal, we publish pilot studies only in exceptional circumstances and we do not publish protocol papers or letters to the editors. The goal of this editorial is to highlight to our readers and authors the process by which we identify which papers to review and publish along with our editorial priorities.

Concepts: Psychology, Cohort study, Evaluation methods, Experimental design, Statistical data types, Study design, Randomized controlled trial, Scientific method


There is a growing body of evidence demonstrating that sexual activity is important to the quality of life of older adults, and that it can be influenced by physical, psychological, and social factors. However, older adults' experiences of sexual difficulties remain relatively unexplored. This article draws on qualitative data collected as part of the English Longitudinal Study of Ageing (ELSA). Participants answered a Sexual Relationships and Activities Questionnaire (SRA-Q), which included an open comment box for further details, 1,084 (1/7) of which were completed. These data were analyzed using Template Analysis, and findings on the experiences of sexual difficulties are presented in this article. Sexual difficulties were contextualized within the couple relationship and could be detrimental to the relationship, particularly if the partner would not seek professional help. Participants reported that sexual difficulties could also have a negative impact on psychological well-being, described mainly as frustration, depression, and sadness. For some participants the supportive nature of their relationship buffered these impacts. Few had sought professional help; those who had reported helpful and unhelpful experiences. These findings add to the limited evidence base and have implications for health care in the context of global aging and a growing recognition of older adults' sexual rights.

Concepts: Aging, Psychology, Gerontology, Sexual intercourse, Statistical data types, Ageing, Human sexual behavior, Sociology


Progress has recently been made in understanding the genetic basis of schizophrenia and other psychiatric disorders. Longitudinal studies are complicated by participant dropout, which could be related to the presence of psychiatric problems and associated genetic risk. We tested whether common genetic variants implicated in schizophrenia were associated with study nonparticipation among 7,867 children and 7,850 mothers from the Avon Longitudinal Study of Parents and Children (ALSPAC; 1991-2007), a longitudinal population cohort study. Higher polygenic risk scores for schizophrenia were consistently associated with noncompletion of questionnaires by study mothers and children and nonattendance at data collection throughout childhood and adolescence (ages 1-15 years). These associations persisted after adjustment for other potential correlates of nonparticipation. Results suggest that persons at higher genetic risk for schizophrenia are likely to be underrepresented in cohort studies, which will underestimate risk of this and related psychiatric, cognitive, and behavioral phenotypes in the population. Statistical power to detect associations with these phenotypes will be reduced, while analyses of schizophrenia-related phenotypes as outcomes may be biased by the nonrandom missingness of these phenotypes, even if multiple imputation is used. Similarly, in complete-case analyses, collider bias may affect associations between genetic risk and other factors associated with missingness.

Concepts: Mental disorder, Epidemiology, Experimental design, Statistical data types, Research methods, Sociology, Longitudinal study, Cohort study


BRIGHTLIGHT is a national evaluation of cancer services for teenagers and young adults in England. Following challenges with recruitment, our aim was to understand more fully healthcare professionals' perspectives of the challenges of recruiting young people to a low-risk observational study, and to provide guidance for future recruitment processes.

Concepts: Experimental design, Clinical trial, Educational psychology, Research methods, Statistical data types, Recruitment, Scientific method, Evaluation methods