Bayesian rank likelihood-based estimation: An application to low birth weight in Ethiopia.

BACKGROUND: Low birth weight is a significant risk factor associated with high rates of neonatal and infant mortality, particularly in developing countries. However, most studies conducted on this topic in Ethiopia have small sample sizes, often focusing on specific areas and using standard models employing maximum likelihood estimation, leading to potential bias and inaccurate coverage probability. METHODS: This study used a novel approach, the Bayesian rank likelihood method, within a latent traits model, to estimate parameters and provide a nationwide estimate of low birth weight and its risk factors in Ethiopia. Data from the Ethiopian Demographic and Health Survey (EDHS) of 2016 were used as a data source for the study. Data stratified all regions into urban and rural areas. Among 15, 680 representative selected households, the analysis included complete cases from 10, 641 children (0-59 months). The evaluation of model performance considered metrics such as the root mean square error, the mean absolute error, and the probability coverage of the corresponding 95% confidence intervals of the estimates. RESULTS: Based on the values of root mean square error, mean absolute error, and probability coverage, the estimates obtained from the proposed model outperform the classical estimates. According to the result, 40.92% of the children were born with low birth weight. The study also found that low birth weight is unevenly distributed across different regions of the country with the highest amounts of variation observed in the Afar, Somali and Southern Nations, Nationalities, and Peoples regions as represented by the latent trait parameter of the model. In contrast, the lowest low birth weight variation was recorded in the Addis Ababa, Dire Dawa, and Amhara regions. Furthermore, there were significant associations between birth weight and several factors, including the age of the mother, number of antenatal care visits, order of birth and the body mass index as indicated by the average posterior beta values of (ß1= -0.269, CI=-0.320, -0.220), (ß2= -0.235, CI=-0.268, -0.202), (ß3= -0.120, CI=-0.162, -0.074) and (ß5= -0.257, CI=-0.291, -0.225). CONCLUSIONS: The study showed that the low birth weight estimates obtained from the latent trait model outperform the classical estimates. The study also revealed that the prevalence of low birth weight varies between different regions of the country, indicating the need for targeted interventions in areas with a higher prevalence. To effectively reduce the prevalence of low birth weight and improve maternal and child health outcomes, it is important to concentrate efforts on regions with a higher burden of low birth weight. This will help implement interventions that are tailored to the unique challenges and needs of each area. Health institutions should take measures to reduce low birth weight, with a special focus on the factors identified in this study.

Epidemiology of emergency and elective caesarean section and its association with early neonatal mortality in sub-Saharan African countries.

INTRODUCTION: Investigating elective and emergency caesarean section (CS) separately is important for a better understanding of birth delivery modes in the sub-Saharan Africa (SSA) region and identifying bottlenecks that prevent favourable childbirth outcomes in SSA. This study aimed at evaluating the prevalences of both CS types, determining their associated socioeconomic factors and their association with early neonatal mortality in SSA. METHODS: SSA countries Demographic and Health Surveys data that had collected information on the CS' timing were included in our study. A total of 21 countries were included in this study, with a total of 155 172 institutional live births. Prevalences of both CS types were estimated at the countries' level using household sampling weights. Multilevel models were fitted to identify associated socioeconomic factors of both CS types and their associations with early neonatal mortality. RESULTS: The emergency CS prevalence in SSA countries was estimated at 4.6% (95% CI 4.4-4.7) and was higher than the elective CS prevalence estimated at 3.4% (95% CI 3.3-3.6). Private health facilities' elective CS prevalence was estimated at 10.2% (95% CI 9.3-11.2) which was higher than the emergency CS prevalence estimated at 7.7% (95% CI 7.0-8.5). Conversely, in public health facilities, the emergency CS prevalence was estimated at 4.0% (95% CI 3.8-4.2) was higher than the elective CS prevalence estimated at 2.7% (95% CI 2.6-2.8). The richest women were more likely to have birth delivery by both CS types than normal vaginal delivery. Emergency CS was positively associated with early neonatal mortality (adjusted OR=2.37, 95% CI 1.64-3.41), while no association was found with elective CS. CONCLUSIONS: Findings suggest shortcomings in pregnancy monitoring, delivery preparation and postnatal care. Beyond antenatal care (ANC) coverage, more attention should be put on quality of ANC, postnatal care, emergency obstetric and newborn care for favourable birth delivery outcomes in SSA.

Non-inferiority test for a continuous variable with a flexible margin in an active controlled trial: an application to the "Stratall ANRS 12110 / ESTHER" trial.

BACKGROUND: Non-inferiority trials are becoming increasingly popular in public health and clinical research. The choice of the non-inferiority margin is the cornerstone of such trials. Most of the time, the non-inferiority margin is fixed and constant, determined from historical trials as a fraction of the effect of the reference intervention. But in some circumstances, there may some uncertainty around the reference treatment that one would like to account for when performing the hypothesis testing. In this case, the non-inferiority margin is not fixed in advance and depends on the reference intervention estimate. Hence, the uncertainty surrounding the non-inferiority margin should be accounted for in statistical tests. In this work, we explore how to perform the non-inferiority test for a continuous variable with a flexible margin. METHODS: We have proposed in this study, two procedures for the non-inferiority test with a flexible margin for continuous endpoints. The proposed test procedures are based on a test statistic and confidence interval approaches respectively. Simulations have been used to assess the performances and properties of the proposed test procedures. An application was done on a real-world clinical data, to assess the efficacy of clinical monitoring alone versus laboratory and clinical monitoring in HIV-infected adult patients. RESULTS: Basically, for both proposed methods, the type I error estimate was not dependent on the values of the reference treatment. In the test statistic approach, the type 1 error rate estimate was approximatively equal to the nominal value. It has been found that the confidence interval level determined approximatively the level of significance. For a given nominal type I error α, the appropriate one- and two-sided confidence intervals should be with levels 1-α and 1-2α, respectively. CONCLUSIONS: Based on the type I error rate and power estimates, the proposed non-inferiority hypothesis test procedures had good performances and were applicable in practice. TRIAL REGISTRATION: ClinicalTrials.gov NCT00301561. Registered on March 13, 2006, url: https://clinicaltrials.gov/ct2/show/NCT00301561 .

Knowledge, Attitudes and Practices (KAP) on Rift Valley Fever among Pastoralist Communities of Ijara District, North Eastern Kenya.

Outbreaks of Rift Valley fever (RVF), a mosquito-borne viral zoonosis, have previously been associated with unusually heavy rainfall and extensive flooding. The disease is a serious public health problem in Africa and the Middle East, and is a potential global health threat. In Kenya, outbreaks of the disease have disproportionately affected impoverished pastoralist communities. This study sought to assess the knowledge, attitudes and practices (KAP) regarding RVF among the pastoralists of North Eastern Kenya, and to establish the determinants of KAP on RVF. A cross-sectional study involving 392 pastoralists living in Ijara district (Masalani and Ijara wards) was carried out using an interview questionnaire. All respondents interviewed (100%) had heard about RVF disease. They recognized that the disease is dangerous (99%), and had a positive attitude towards vaccination of animals (77%). However, few respondents knew that abortion (11%) and high mortality of young animals (10%) were key signs of RVF in animals. Very few (4%) use any form of protection when handling sick animals to avoid infection. Significant factors associated with knowledge were being in a household with a history of RVF infection (OR = 1.262, 95% CI = 1.099-1.447), having more livestock (OR = 1.285, 95% CI = 1.175-1.404) and the place of residence, Masalani (OR = 0.526, 95% CI = 0.480-0.576). Overall knowledge score on RVF was found to be a significant predictor of good preventive practice of the disease (OR = 1.073, 95% CI = 1.047-1.101). Despite the positive attitude that pastoralist communities have towards the prevention of RVF, there exist gaps in knowledge and good practices on the disease. Therefore there is need for public health education to address these gaps, and to identify and facilitate the removal of barriers to behavioural change related to the prevention of RVF.

Laboratory evaluation of the aqueous extract of Azadirachta indica (neem) wood chippings on Anopheles gambiae s.s. (Diptera: Culicidae) mosquitoes.

Azadirachta indica A. Juss (the neem tree), a source of limonoid insect growth regulatory (IGRs), grows well in many places in sub-Saharan Africa. We explored the potential of neem wood and bark chippings in malaria vector control by evaluating their aqueous extracts as a larvicide and growth disruptor of Anopheles gambiae s.s. (Diptera: Culicidae) under laboratory conditions. Immature stages of the mosquito were tested using WHO guidelines. Fifty percent inhibition of adult emergence (IE50) of all larval instars was obtained with <0.4 g of neem chippings in 1 liter of distilled water. For pupae, significant mortality occurred at 5 g/liter. Inhibition of pupation was seen with some larvae staying as LIVs for 9 d before dying. In addition to growth retardation, reduced reaction by larvae to visual and mechanical stimuli observed at higher neem concentrations may make them more susceptible to natural predators. There were no significant differences in the sex ratio of emerged adults or wing length of females compared with the controls. High-performance liquid chromatography of aqueous extracts showed a series of constituents of varying polarity, including the limonoids nimbin and salannin, which were quantified. Azadirachtin was not detected and the observed activities are attributed to other constituents of the chippings. Such larvicides can be particularly effective where larval habitats are relatively large and readily identifiable. Aqueous extracts of neem wood chippings can be produced locally and their use has the potential to be a low-tech component of integrated malaria vector control schemes in sub-Saharan Africa.

Influence of temperature on virulence of fungal isolates of Metarhizium anisopliae and Beauveria bassiana to the two-spotted spider mite Tetranychus urticae.

Twenty-three isolates of Metarhizium anisopliae (Metschnikoff) Sokorin and three isolates of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales: Clavicipitaceae) were assessed for their virulence against the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Based on the screening results, nine isolates of M. anisopliae and two isolates of B. bassiana were tested for their virulence against young adult (1- to 2-day-old) female T. urticae at constant temperatures of 20, 25, 30 and 35 degrees C. At all temperatures tested, all the fungal isolates were pathogenic to T. urticae but mortality varied with isolates and temperatures. Fungal isolates were more virulent at 25, 30 and 35 degrees C than at 20 degrees C. The lethal time to 50% mortality (LT(50)) and lethal time to 90% mortality (LT(90)) values decreased with increased temperature. There were no significant differences in virulence between fungal isolates at 30 and 35 degrees C; however, significant differences were observed at 20 and 25 degrees C.