The self-controlled case series method was developed to investigate associations between acute outcomes and transient exposures, using only data on cases, that is, on individuals who have experienced the outcome of interest. Inference is within individuals, and hence fixed covariates effects are implicitly controlled for within a proportional incidence framework. We describe the origins, assumptions, limitations, and uses of the method. The rationale for the model and the derivation of the likelihood are explained in detail using a worked example on vaccine safety. Code for fitting the model in the statistical package STATA is described. Two further vaccine safety data sets are used to illustrate a range of modelling issues and extensions of the basic model. Some brief pointers on the design of case series studies are provided. The data sets, STATA code, and further implementation details in SAS, GENSTAT and GLIM are available from an associated website.

TDF use did not attenuate renal function recovery or increase the mortality rate in patients with renal dysfunction. Further studies are needed to determine the role of routine renal function monitoring before and during ART use in Africa.

This study discusses the results of a cross-sectional survey of healthy college students in Poland. More specifically, it describes, explores, and explains the relationships between psychological variables/models such as health behaviors (HB), sense of coherence (SOC), level of optimism (LOO), and self-efficacy (SE) among college students. These separate constructs have also been used to operationalize a positive health attitude (PHA) as a novel construct. The social survey was carried out at three higher education institutions in Poland in January 2006. The random sample of 455 undergraduate students was taken from five different faculties: Physiotherapy, Physical Education, Tourism and Recreation, English Philology and Polish Philology. Four reliable and validated research tools were used to collect the data: Juczynsky's Health Behaviour Inventory (HBI); Antonovsky's Sense of Coherence Questionnaire (SOC-29); Schwarzer & Jerusalem's Generalized Self-Efficacy Scale (GSES); and Seligman's Scale (SS). The results indicate statistically significant differences (p < 0.001) between these four variables: for example, the healthier health behaviors the stronger the sense of coherence, level of optimism and self-efficacy. It was also demonstrated that LOO, SOC, SE, and HB correlate with one another. Finally, these variables create an explicit empirical-theoretical pattern. All the research results from REGWQ tests, Pearson's correlation coefficient and cluster analysis suggest the existence of conceptual similarities between these four variables and/or the existence of some broader scientific construct such as PHA. However, this needs to be examined further. These results could be a good indicator for future research among different faculties or age groups.

IntroductionIn spite of the extreme importance of an early antenatal care visit, more than 50% of Zambian pregnant women book for antenatal care late. We aimed to determine factors associated with late antenatal care booking in Zambia.MethodsData stem from the 2007 Zambia Demographic and Health Survey where information on socio-demographic, social-economic, obstetrical characteristics and timing of the first antenatal visit were extracted on all women aged 15 to 49 years. A weighted survey analysis using STATA version 12 was applied. Firstly, we explored proportions of ANC booking at 0-3 months, 4-5 month and 6-9 months. Secondly, we investigated the association between predictor variables and late antenatal care booking using univariate and multivariate logistic regression.ResultsOverall (n= 3979), the proportion of late ANC booking (booking between 4th to 9th month) was 81% disaggregated as 56% and 19% at 4 to 5 months and 6 to 9 months respectively. Women who wanted their last child later were more likely to book late than those with wanted pregnancies then (AOR: 1.35 95% CI 1.10-1.66). Women with higher education were 55% less likely to book for ANC late compared to women with no education (AOR: 0.45 95%CI: 0.27-0.74). Women aged 20-34 years were 30% more likely to book earlier than women younger than 20 years (AOR: 0.69 95% CI 0.50-0.97).ConclusionWe found high proportion of late ANC booking associated with presence of unplanned or unwanted pregnancies in this population. The concentration of this problem in lower or no education groups may be an illustration of existing inequalities which might further explain limitations in health promotion messages meant to mitigate this challenge. There is thus urgent need to re-pack health promotion message to specifically target this and related poor groups.

SUMMARYWe derive several formulae for the sample size required for a study designed using the self-controlled case series method without age effects. We investigate these formulae by simulation, and identify one based on the signed root likelihood ratio statistic which performs well. We extend this method to allow for age effects, which can have a big impact on the sample size needed. This more general sample size formula is also found to perform well in a broad range of situations.

BACKGROUND: This study aimed to show the longitudinal use of routinely collected clinical data from history and ultrasound evaluation of the endometrium in developing an algorithm to predict the risk of endometrial carcinoma for postmenopausal women presenting with vaginal bleeding. METHODS: This prospective study collected data from 3047 women presenting with postmenopausal bleeding. Data regarding the presence of risk factors for endometrial cancer was collected and univariate and multivariate analyses were performed. RESULTS: Age distribution ranged from 35 to 97 years with a median of 59 years. A total of 149 women (5% of total) were diagnosed with endometrial carcinoma. Women in the endometrial cancer group were significantly more likely to be older, have higher BMI, recurrent episodes of bleeding, diabetes, hypertension, or a previous history of breast cancer. An investigator best model selection approach was used to select the best predictors of cancer, and using logistic regression analysis we created a model, 'Norwich DEFAB', which is a clinical prediction rule for endometrial cancer. The calculated Norwich DEFAB score can vary from a value of 0 to 9. A Norwich DEFAB value equal to or greater than 3 has a positive predictive value (PPV) of 7.78% and negative predictive value (NPV) of 98.2%, whereas a score equal to or greater than 5 has a PPV of 11.9% and NPV of 97.8%. CONCLUSION: The combination of clinical information with our investigation tool for women with postmenopausal vaginal bleeding allows the clinician to calculate a predicted risk of endometrial malignancy and prioritise subsequent clinical investigations.

BackgroundAdolescent pregnancies pose a risk to the young mothers and their babies. In Zambia, 35% of young girls in rural areas have given birth by the age of 18 years. Pregnancy rates are particularly high among out-of-school girls. Poverty, low enrolment in secondary school, myths and community norms all contribute to early childbearing. This protocol describes a trial aiming to measure the effect on early childbearing rates in a rural Zambian context of (1) economic support to girls and their families, and (2) combining economic support with a community intervention to enhance knowledge about sexual and reproductive health and supportive community norms.Methods/designThis cluster randomized controlled trial (CRCT) will have three arms. The clusters are rural schools with surrounding communities. Approximately 4900 girls in grade 7 in 2016 will be recruited from 157 schools in 12 districts. In one intervention arm, participating girls and their guardians will be offered cash transfers and payment of school fees. In the second intervention arm, there will be both economic support and a community intervention. The interventions will be implemented for approximately 2 years. The final survey will be 4.5 years after recruitment. The primary outcomes will be “incidence of births within 8 months of the end of the intervention period”, “incidence of births before girls’ 18th birthday” and “proportion of girls who sit for the grade 9 exam”. Final survey interviewers will be unaware of the intervention status of respondents. Analysis will be by intention-to-treat and adjusted for cluster design and confounders. Qualitative process evaluation will be conducted.DiscussionThis is the first CRCT to measure the effect of combining economic support with a community intervention to prevent adolescent childbearing in a low- or middle-income country. We have designed a programme that will be sustainable and feasible to scale up. The findings will be relevant for programmes for adolescent reproductive health in Zambia and similar contexts.Trial registrationISRCTN registry: ISRCTN12727868, (4 March 2016).Electronic supplementary materialThe online version of this article (doi:10.1186/s13063-016-1682-9) contains supplementary material, which is available to authorized users.

Background:To synthesize and evaluate the impact of implementing post-2010 World Health Organization (WHO) prevention of mother-to-child transmission (PMTCT) guidelines on attainment of PMTCT targets.Methods:Retrospective and prospective cohort study designs that utilized routinely collected data with a focus on provision and utilization of the cascade of PMTCT services were included. The outcomes included the proportion of pregnant women who were tested during their antenatal clinic (ANC) visits; mother-to-child transmission (MTCT) rate; adherence; retention rate; and loss to follow-up (LTFU).Results:Of the 1210 references screened, 45 met the inclusion criteria. The studies originated from 14 countries in sub-Saharan Africa. The highest number of studies originated from Malawi (10) followed by Nigeria and South Africa with 7 studies each. More than half of the studies were on option A while the majority of option B+ studies were conducted in Malawi. These studies indicated a high uptake of human immunodeficiency virus (HIV) testing ranging from 75% in Nigeria to over 96% in Zimbabwe and South Africa. High proportions of CD4 count testing were reported in studies only from South Africa despite that in most of the countries CD4 testing was a prerequisite to access treatment. MTCT rate ranged from 1.1% to 15.1% and it was higher in studies where data were collected in the early days of the WHO 2010 PMTCT guidelines. During the postpartum period, adherence and retention rate decreased, and LTFU increased for both HIV-positive mothers and exposed infants.Conclusion:Irrespective of which option was followed, uptake of antenatal HIV testing was high but there was a large drop off along later points in the PMTCT cascade. More research is needed on how to improve later components of the PMTCT cascade, especially of option B+ which is now the norm throughout sub-Saharan Africa.