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bioRxiv2018

Prevalence and factors associated with Skilled Birth Attendants use among post-partum women in Arusha Tanzania

IntroductionDeath related to pregnancy complications and delivery remains a public health problem in developing countries including Tanzania where majority of women and newborns die each year due to preventable causes. Delivery with a skilled birth attendant (SBA) is an important intervention to avert maternal and newborn mortality. This study aimed to determine factors influencing skilled birth attendants use among postpartum women in Arusha city and Arumeru district in Arusha region.\n\nMethodsThis was a cross-sectional study which was conducted from April to July 2017. The study utilized secondary data from the parent study which was conducted in Arusha city and Arumeru district in Arusha region. The parent study aimed to assess knowledge of danger signs in obstetric complication, birth preparedness and utilization of skilled birth attendants among post-partum women in urban and rural Arusha region in Tanzania. Data analysis was performed using SPSS version 20. Chi square statistics was used to determine the association between a set of independent variables and utilization of skilled birth attendance in bivariate analysis. Odds ratios with 95% confidence interval for factors influencing skilled birth attendants use were estimated in a multivariable logistic regression models. A p-value of less than 0.05 was considered statistically significant.\n\nResultsA total of 1218 post-partum women were studied. Their mean age was 26.2 (SD 5.9) years. Of these, 1020 used skilled birth attendants during delivery; this corresponds to prevalence of 83.7%. Mothers education level, area of residence, distance from health facility, frequency of antenatal care and parity were significantly associated utilization of skilled birth attendants during delivery.\n\nConclusionThe prevalence of skilled birth attendants use among postpartum women is high in the studied population compared to the national level. Strategies to create community awareness on important of skilled birth attendants use will increase its uptake and my help to reduce both mother and child mortality.

epidemiology↗
bioRxiv2018

Structure and consistency of self-reported social contact networks in British secondary schools

Self-reported social mixing patterns are commonly used in mathematical models of infectious diseases. It is particularly important to quantify patterns for school-age children given their disproportionate role in transmission, but it remains unclear how the structure of such social interactions changes over time. By integrating data collection into a public engagement programme, we examined self-reported contact networks in year 7 groups in four UK secondary schools. We collected data from 460 unique participants across four rounds of data collection conducted between January and June 2015, with 7,315 identifiable contacts reported in total. Although individual-level contacts varied over the study period, we were able to obtain out-of-sample accuracies of more than 90% and F-scores of 0.49-0.84 when predicting the presence or absence of social contacts between specific individuals across rounds of data collection. Network properties such as clustering and number of communities were broadly consistent within schools between survey rounds, but varied significantly between schools. Networks were assortative according to gender, and to a lesser extent school class, with the estimated clustering coefficient larger among males in all surveyed co-educational schools. Our results demonstrate that it is feasible to collect longitudinal self-reported social contact data from school children and that key properties of these data are consistent between rounds of data collection.

epidemiology↗
bioRxiv2018

A dynamic power-law sexual network model of gonorrhoea outbreaks

Human networks of sexual contacts are dynamic by nature, with partnerships forming and breaking continuously over time. Sexual behaviours are also highly heterogeneous, so that the number of partners reported by individuals over a given period of time is typically distributed as a power-law. Both the dynamism and heterogeneity of sexual partnerships are likely to have an effect in the patterns of spread of sexually transmitted diseases. To represent these two fundamental properties of sexual networks, we developed a stochastic process of dynamic partnership formation and dissolution, which results in power-law numbers of partners over time. Model parameters can be set to produce realistic conditions in terms of the exponent of the power-law distribution, of the number of individuals without relationships and of the average duration of relationships. Using an outbreak of antibiotic resistant gonorrhoea amongst men have sex with men as a case study, we show that our realistic dynamic network exhibits different properties compared to the frequently used static networks or homogeneous mixing models. We also consider an approximation to our dynamic network model in terms of a much simpler branching process. We estimate the parameters of the generation time distribution and offspring distribution which can be used for example in the context of outbreak reconstruction based on genomic data. Finally, we investigate the impact of a range of interventions against gonorrhoea, including increased condom use, more frequent screening and immunisation, concluding that the latter shows great promise to reduce the burden of gonorrhoea, even if the vaccine was only partially effective or applied to only a random subset of the population.

epidemiology↗
bioRxiv2018

The Roles of Neighborhood Composition and Autism Prevalence on Vaccination Exemption Pockets: A Population-wide Study

The number of children entering schools without mandated vaccinations has increased in high-income countries due to the rise of nonmedical exemptions from school vaccination requirements. Herd immunity is threatened when unvaccinated children are concentrated in spatial pockets. It is often assumed that these exemption clusters are merely the result of population composition. On the other hand, despite the role of vaccine-autism controversy to the current wave of anti-vaccine movement, we do not know if exemption clusters are associated with local autism rates. Our spatial analysis of California shows that while racial/ethnic composition is associated with the locations of large exemption pockets, other sociodemographic factors and access to health care resources have limited geographical span. We decouple the race/ethnicity effect from that of unobserved socioeconomic status by examining families in poverty. Using unique address-level data on the locations of the majority of children with an autism diagnosis, we show that the prevalence of autism is not associated with the locations of large pockets of vaccination exemptions. In addition, we find charter schools in most exemption clusters; potential spillovers from charter schools to neighboring public schools are evaluated. Exemption pockets are not merely the result of population composition and community-level interventions are needed to maintain herd immunity.\n\nHighlightsO_LIAutism prevalence rates are not associated with the locations of large exemption pockets.\nC_LIO_LIThe average exemption rate in charter schools (7.5%) was higher than private schools.\nC_LIO_LIProportion non-Hispanic white has the strongest association with large exemption clusters.\nC_LIO_LIPopulation composition cannot fully explain the exemption clusters.\nC_LI

epidemiology↗
bioRxiv2018

Projecting the end of the Zika virus epidemic in Latin America: a modelling analysis

Background Zika virus (ZIKV) emerged in Latin America & the Caribbean (LAC) region in 2013, and has had serious implications for population health in the region. In 2016, the World Health Organization declared the ZIKV outbreak a Public Health Emergency of International Concern following a cluster of associated neurological disorders and neonatal malformations. In 2017, Zika cases declined, but future incidence in LAC remains uncertain due to gaps in our understanding, considerable variation in surveillance and a lack of a comprehensive collation of data from affected countries.\n\nMethods Our analysis combines information on confirmed and suspected Zika cases across LAC countries and a spatio-temporal dynamic transmission model for ZIKV infection to determine key transmission parameters and projected incidence in 91 major cities within 35 countries. Seasonality was determined by spatio-temporal estimates of Aedes aegypti vector capacity. We used country and state-level data from 2015 to mid-2017 to infer key model parameters, country-specific disease reporting rates, and the 2018 projected incidence. A 10-fold cross-validation approach was used to validate parameter estimates to out-of-sample epidemic trajectories.\n\nResults There was limited transmission in 2015, but in 2016 and 2017 there was sufficient opportunity for wide-spread ZIKV transmission in most cities, resulting in the depletion of susceptible individuals. We predict that the highest number of cases in 2018 within some Brazilian States (Sao Paulo and Rio de Janeiro), Colombia and French Guiana, but the estimated number of cases were no more than a few hundred. Model estimates of the timing of the peak in incidence were correlated (p<0.05) with the reported peak in incidence. The reporting rate varied across countries, with lower reporting rates for those with only confirmed cases compared to those who reported both confirmed and suspected cases.\n\nConclusions The findings suggest that the ZIKV epidemic is by and large over, with incidence projected to be low in most cities in LAC in 2018. Local low levels of transmission are probable but the estimated rate of infection suggests that most cities have a population with high levels of herd immunity.

epidemiology↗
bioRxiv2018

Are you suppressed? Viral load test coverage for people living with HIV in Mutare District, Manicaland Province, Zimbabwe, 2015-2017

BackgroundThe third 90-90-90 UNAIDS goal require that 90% of people living with HIV (PLHIV) on antiretroviral treatment (ART) achieve viral load (VL) suppression. This study assessed the proportion of VL suppression and related factors among PLHIV on 1st and 2nd line ART in Mutare District, Manicaland Province, Zimbabwe between 2015-2017.\n\nMethodsA retrospective study using routine HIV programme data from the electronic monitoring system for nine health facilities in Mutare District. VL suppression was defined as < 1,000 copies/ml.\n\nResultsOf 16,590 registered patients, 15,566(94%) were on first-line and 1024(6%) on second-line ART. Of those on 1st-line ART, 2856(18%) had a VL test result documented, while 367(36%) of 2nd-line ART patients had VL results. VL suppression rates were 86% among those on 1st-line and 45% in 2nd-line ART. Independent risk factors associated with VL non-suppression for those on 1st-line ART were age 0-9 years (adjusted relative risk, aRR=2.9; 95% confidence interval, CI=1.7-4.8;P<0.001), 10-19 years (aRR=2.2;95%CI=1.4-3.2,P<0.001) compared to those 20-49 years, concurrent TB (aRR=9; CI=3.0-29.7,P<0.001) and male gender (aRR=1.5,95%CI=1.1-2.1;P=0.02). There were no significant risk factors associated with VL non-suppression for 2nd-line ART patients.\n\nConclusionFor PLHIV on 1st-line ART in Mutare district, Manicaland, Zimbabwe, the frequency of reported VL results were only 18% among those on 1st-line ART, while the rate of VL suppression was near 90%. Viral Load testing coverage appears to be lagging behind current Zimbabwe goals and increased support is needed to improve the quality of HIV care and help reduce the threat of possible HIV drug resistance in the future.

epidemiology↗
bioRxiv2018

Planning a future randomized clinical trial based on a network of relevant past trials

Background: The important role of network meta-analysis of randomized clinical trials in health technology assessment and guideline development is increasingly recognized. This approach has the potential to obtain conclusive results earlier than with new standalone trials or conventional, pairwise meta-analyses.\n\nMethods: Network meta-analyses can also be used to plan future trials. We introduce a four-steps framework to plan a new trial that aims to identify the optimal new design that will update the existing evidence to best serve timely clinical and public health decision making. The new trial designed within this framework does not need to include all competing interventions and comparisons of interest and can contribute direct and indirect evidence to the updated network meta-analysis. We present the method by virtually planning a new trial to compare biologics in rheumatoid arthritis and a new trial to compare two drugs for relapsing-remitting multiple sclerosis.\n\nResults: A trial design based on updating the evidence from a network meta-analysis of relevant previous trials may require a considerably smaller sample size to reach the same conclusion compared with a trial designed and analyzed in isolation. Challenges in the approach include the complexity of the methodology and the need for a coherent network meta-analysis of previous trials with little heterogeneity.\n\nConclusions: When used judiciously, conditional trial design could significantly reduce waste in clinical research.

epidemiology↗
bioRxiv2018

Novel immune cell subtypes linked to survival among African American women with triple-negative breast cancer

Triple negative breast cancer (TNBC) is an aggressive disease that is twice as likely to be diagnosed in African American (AA) women compared to white women, with poor clinical outcomes. Tumor infiltrating lymphocytes (TILs) are associated with improved survival for TNBC, but the relevance of TILs and immune cell subtypes to survival in AA women with TNBC is unknown. We evaluated histopathologic TIL counts and molecular characteristics among 60 AA women diagnosed with TNBC with linkage to clinical outcomes using data from the Metropolitan Detroit Cancer Surveillance System. We utilized whole genome expression profiling of TN tumors and cell type deconvolution analysis to evaluate the underlying mechanisms and immune cell subtypes associated with survival patterns in the context of TILs. TILs were significantly associated with improved survival [1-10% Hazard Ratio (HR)=0.32, 95% Confidence Interval (CI) 0.12-0.90, p=0.031; >10% HR=0.18, 95% CI 0.05-0.67, 9.9x10-3]. 524 transcripts (326 coding, 198 non-coding) were associated with TIL levels, 34 of which were associated with both TILs and survival (p<0.05). While only naive B cells were associated with survival when considering individual cell types [Median HR=2.43, 95% CI 1.07-5.55, p=0.035], increased naive B cells, plasma cells, and activated NK cells, and decreased resting mast cells, M1 macrophages, and monocytes were associated with transcripts that predicted worse survival. These data provide evidence for novel roles for these immune cells types in TNBC, and further studies are needed to validate these findings and identify determinants of patterns of immune response in TNBC relevant to the AA population.\n\nSummaryWe found that increased naive B cells, plasma cells, and activated natural killer cells, and decreased resting mast cells, M1 macrophages, and monocytes were associated with expression biomarkers of worse survival among African American women with triple negative breast cancer.

epidemiology↗
bioRxiv2018

Developmental factors associated with decline in grip strength from midlife to old age: a British birth cohort study

Maintenance of muscle strength is important for healthy ageing, protecting against chronic disease and enabling independent living. We tested whether developmental factors were associated with grip strength trajectories between 53 and 69 years, and operated independently or on the same pathway/s as adult factors, in 3058 participants from a British birth cohort. Grip strength (kg) at ages 53, 60-64 and 69, was analysed using multilevel models, testing for age and sex interactions, to estimate associations with developmental factors (birthweight, growth parameters, motor and cognitive development) and childhood socioeconomic position (SEP) and investigate potential adult mediators. Heavier birthweight, beginning to walk on time, later puberty and greater weight 0-26 years in men, and earlier age at first standing in women, were associated with stronger grip but not with its decline; these associations were independent of adult factors. The slower decline in grip strength (by 0.068kg/year, 95% confidence interval (CI) 0.024,0.11 per 1SD, p=.003) in men with higher childhood cognition was attenuated by adult verbal memory which became increasingly positively associated with grip strength at older ages. Thus grip strength may increasingly reflect neural ageing processes. Targeting developmental factors to promote muscle development should increase the chance of independence in old age.

epidemiology↗
bioRxiv2018

Spousal Concordance in Telomere Length: New Evidence from Older Adults in the US

Telomere length (TL) has been associated with a range of aging outcomes as well as mortality. Recent research has shown both high heritability ([~]70 %) of TL as well as moderate spousal similarity (r[~].3) using European datasets. This paper explores the level of spousal concordance in telomere length in the Health and Retirement Study, a national sample of adults in the US. The results both show that the spousal similarity in TL is lower in the US and also varies by the length of time spouses have been married as well as the educational attainments of husbands. These findings suggest the possibility of both assortative mating patterns related to telomere length as well as likelihood of shared environmental factors that cause similarity in TL in people who are socially connected.

epidemiology↗
bioRxiv2018

Seroprevalence of Hepatitis B and C among Healthcare Workers in Dutse Metropolis Jigawa State, Nigeria

Hepatitis is one of the neglected infectious diseases in sub Saharan Africa and most of the available data is based on blood donors. Health care workers (HCWs) often get infected as a result of their close contact with patients. A cross sectional study was conducted to determine the prevalence of hepatitis B and C among this group of professionals with a view to improving the quality of care to their patients. Hepatitis B and C infections pose a major public health problem worldwide. While infection is highest in the developing world particularly Asia and sub-Saharan Africa, healthcare workers are at higher risk of acquiring blood-borne viral infections, particularly Hepatitis B and C which are mostly asymptomatic. This study was aimed at determining the prevalence of Hepatitis B and C infections and associated risk factors among health care workers in Dutse Metropolis, Jigawa State - Nigeria. A standard rapid immuno-chromatographic technique i.e. rapid ELISA was used to screen all sera for Hepatitis B surface antigen (HBsAg) and Hepatitis C viral antibody (HCVAb) respectively. Strips containing coated antibodies and antigens to HBV and HCV respectively were removed from the foil. Strips were labeled according to samples. Using a separate disposable pipette, 2 drops of the sample (plasma) were added into each test strip and allowed to run across the absorbent pad. Results were read after 15 minutes. The prevalence of HBV and HCV infection in 100 healthcare workers was determined by testing the plasma collected from the clients during their normal checkup using HBsAg and HCVAb test strips. Results were subjected to statistical analysis using chi-square test. The prevalence of HBV among HCWs was 19 out of 100 (19.0%) and that of HCV was 5 out of 100 (5.0%) where in both cases, higher prevalence was observed among female nurses. It was also observed that all HCV positive cases were recorded among nurses only. The study revealed that nurses are at greater risk of contracting HBV and HCV due to their frequent contact with patients. It is therefore recommended that effective vaccination and other infection control measures be encouraged among healthcare workers.

epidemiology↗
bioRxiv2018

Emergence of a Dengue virus serotype 2 causing the largest ever dengue epidemic in Sri Lanka

BackgroundSri Lanka experienced the largest ever dengue outbreak in year 2017, which coincided with the shift of the predominant circulating dengue virus (DENV) 1 to DENV2 after 9 years. As it was felt that more patients appeared to develop complications and severe dengue, we compared clinical features of patients with acute dengue, with the previous circulating serotype (DENV1) and also sequenced the new virus, to determine the lineage of the virus.\n\nMethodology/Principal findingsWe studied the clinical and laboratory features of 172 adult patients with acute DENV1 (n=79) and DENV2 (n=93) infection. 65 (82.3%) of those with DENV1 and 86 (92.4%) of those with DENV2 were experiencing a secondary infection. The risk of developing dengue haemorrhagic fever (DHF) was significantly higher (=0.005, odds ratio=2.5) in those infected with DENV2 (54.8%) when compared to DENV1(32.9%), even though similar proportions of patients had a secondary dengue infection. Patients with DENV2 infection developed leakage significantly earlier (p<0.0001, median= 3, days) when compared to those with a DENV1 infection (median 5 days) and were more likely to develop significant bleeding and to require blood transfusions. Furthermore, patients with DENV2 were more likely to have significantly lower platelet counts during day 3, 4 and 5 since onset of illness.\n\nWhole genome sequencing showed that these DENV-2 isolates belonged to a cosmopolitan strain and was genetically more distant than the DENV-2 strains that circulated from 1981 to 2004 in Sri Lanka.\n\nConclusions/significanceSince this DENV2 strain appears to cause more severe forms of clinical disease, it would be important to determine variations in the virus genome or other factors that could have contributed to severe disease.\n\nAuthor summarySri Lanka experienced the largest ever dengue outbreak in year 2017, which coincided with the shift of the predominant circulating dengue virus (DENV) 1 to DENV2 after 9 years. We studied the clinical and laboratory features of 172 adult patients with acute DENV1 (n=79) and DENV2 (n=93) infection. The risk of developing dengue haemorrhagic fever was significantly higher (=0.005, odds ratio=2.5) in those infected with DENV2 (54.8%) when compared to DENV1(32.9%), even though similar proportions of patients had a secondary dengue infection. Patients with DENV2 infection developed leakage significantly earlier (p<0.0001, median= 3, days) when compared to those with a DENV1 infection (median 5 days) and were more likely to develop significant bleeding. Whole genome sequencing showed that these DENV-2 isolates belonged to cosmopolitan strain and was genetically more distant to the DENV-2 strains that circulated from 1981 to 2004 in Sri Lanka.

epidemiology↗
bioRxiv2018

The Charlson Index is insufficient to control for comorbidities in a national trauma registry

BackgroundThe Charlson Comorbidity Index (CCI) is frequently used to control for confounding by comorbidities in observational studies, but its performance as such has not been studied. We evaluated the performance of CCI and an alternative summary method, logistic principal component analysis (LPCA), to adjust for comorbidities, using as an example the association between insurance and mortality.\n\nMaterials and MethodsUsing all admissions in the National Trauma Data Bank 2010-2015, we extracted mortality, payment method, and 36 ICD-9-derived comorbidities. We estimated ORs for the association between uninsured status and mortality before and after adjusting for CCI, LPCA, and separate covariates. We also calculated standardized mean differences (SMDs) of comorbidity variables before and after weighting the sample using inverse probability of treatment weights (IPTW) for CCI, LPCA, and separate covariates.\n\nResultsIn 4,936,880 admissions, most (68.3%) had at least one comorbidity. Considerable imbalance was observed in the unweighted sample (mean SMD=0.086, OR=1.17), which was almost entirely eliminated by IPTW on separate covariates (mean SMD=0.012, OR=1.36). The CCI performed similarly to the unweighted sample (mean SMD=0.080, OR=1.25), while 2 LPCA axes were better able to control for confounding (mean SMD=0.04, OR=1.31). Using covariate adjustment, the CCI accounted for 56.1% of observed confounding, whereas 2 LPCA axes accounted for 91.3%.\n\nConclusionsThe use of the CCI to adjust for confounding may result in residual confounding, and alternative strategies should be considered. LPCA may be a viable alternative to adjusting for each comorbidity when samples are small or positivity assumptions are violated.

epidemiology↗
bioRxiv2018

Neutrophil counts and cancer prognosis: an umbrella review of systematic reviews and meta-analyses of observational studies

OBJECTIVETo evaluate the strength and validity of evidence on the association between the neutrophil to lymphocyte ratio (NLR) or tumour-associated neutrophils (TAN) and cancer prognosis.\n\nDESIGNUmbrella review of systematic reviews and meta-analyses of observational studies.\n\nDATA SOURCESMedline, EMBASE, and Cochrane Database of Systematic Reviews.\n\nELIGIBILITY CRITERIASystematic reviews or meta-analyses of observational studies evaluating the association between NLR or TAN and specific cancer outcomes related to disease progression or survival.\n\nDATA SYNTHESISThe available evidence was graded as strong, highly suggestive, suggestive, or weak through the application of pre-set grading criteria. For each included meta-analysis, the grading criteria considered the significance of the random effects estimate, the significance of the largest included study, the number of studies and individuals included, the heterogeneity between included studies, the 95% prediction intervals, presence of small study effects, excess significance and credibility ceilings.\n\nRESULTS239 meta-analyses investigating the association between NLR or TAN and cancer outcomes were identified from 57 published studies meeting the eligibility criteria, with 81 meta-analyses from 36 studies meeting the criteria for inclusion. No meta-analyses found a hazard ratio (HR) in the opposite direction of effect (HR<1). When assessed for significance and bias related to heterogeneity and small study effects, only three (4%) associations between NLR and outcomes in gastrointestinal and nasopharyngeal cancers were supported by strong evidence.\n\nCONCLUSIONDespite many publications exploring the association between NLR and cancer prognosis, the evidence is limited by significant heterogeneity and small study effects. There is a lack of evidence on the association between TAN and cancer prognosis, with all nine associations identified arising from the same study. Further research is required to provide strong evidence for associations between both TAN and NLR and poor cancer prognosis.\n\nREGISTRATIONThis umbrella review is registered on PROSPERO (CRD42017069131)\n\nFUNDINGMedical Research Council\n\nCOPYRIGHTOpen access article under terms of CC BY\n\nSHORT TITLENeutrophils and cancer prognosis: an umbrella review\n\nKEY RESULTWhen assessed for significance and bias related to heterogeneity and small study effects, only three (4%) associations between NLR and overall survival and progression-free survival in gastrointestinal and nasopharyngeal cancers were supported by strong evidence.\n\nWHAT THIS PAPER ADDS\n\nWHAT IS ALREADY KNOWN ON THE TOPICO_LINeutrophil counts have been linked to the progression of cancer due to their tumourigenic role in the cancer microenvironment.\nC_LIO_LINumerous meta-analyses and individual studies have explored the association between neutrophil counts and cancer outcomes for a variety of cancer sites, leading to a large body of evidence with variable strength and validity.\nC_LIO_LIUncertainty exists around the association between neutrophils and cancer outcomes, depending on the site, outcome and treatments considered.\nC_LI\n\nWHAT THIS STUDY ADDSO_LIAll meta-analyses included in this review indicated an association between high neutrophil counts and poor cancer prognosis.\nC_LIO_LIThere is strong evidence supporting the association between the neutrophil to lymphocyte ratio and poor cancer prognosis in some respiratory and gastrointestinal cancers.\nC_LIO_LIFurther research is required to strengthen the existing body of evidence, particularly for the association between tumour-associated neutrophils and cancer outcomes.\nC_LI

epidemiology↗
bioRxiv2018

The association between 25(OH)D levels, frailty status and adiposity indices in older adults

BackgroundVitamin D deficiency is common in older adults and has been linked with frailty and obesity, but it remains to be studied whether frail obese older adults are at higher risk of vitamin D deficiency. Therefore, the aim of this study is to explore the association between frailty, adiposity indices and serum 25(OH)D concentrations.\n\nMethods1447 individuals with 65 years or older, participating in a cross-sectional study (Nutrition UP 65). Frailty, according to Fried et al., body mass index (BMI), waist circumference (WC), body roundness index (BRI) and body shape index (ABSI) were evaluated. A stepwise multinomial logistic regression was carried out to quantify the association between 25(OH)D quartiles and independent variables.\n\nResultsMedian 25(OH)D levels were lower in individuals presenting both frailty and obesity (p<0.001). In the multivariate analysis, pre-frailty (OR 2.65; 95% CI 1.63-4.32) and frailty (OR 3.76; 95% CI 2.08-6.81) were associated with increased odds of lower 25(OH)D serum levels (first quartile). Regarding adiposity indices, obesity (OR 1.75; 95% CI 1.07-2.87) and the highest categories of WC (OR 3.46; 95% CI 1.95-6.15), BRI (OR 4.35; 95% CI 2.60-7.29) and ABSI (OR 3.17 95% CI 1.86-5.38) were directly associated with lower 25(OH)D serum levels (first quartile).\n\nConclusionsA positive association between frailty or obesity and lower levels of vitamin D was found. Moreover, besides BMI and WC, other indicators of body adiposity, such as BRI and ABSI, were associated with lower 25(OH)D serum concentrations.

epidemiology↗
bioRxiv2018

Age-specific differences in the dynamics of protective immunity to influenza

Influenza A viruses evolve rapidly to escape host immunity, such that individuals can be infected multiple times with the same subtype. The form and duration of protective immunity after each influenza infection are poorly understood. Here, we quantify the dynamics of protective immunity against influenza A virus infections by fitting individual-level mechanistic models to longitudinal serology from children and adults in a household cohort study. We find that most protection in children is explained by antibody titers measured by the hemagglutination inhibition (HI) assay. In contrast, in adults, HI antibody titers explain a smaller fraction of protection. Protection against circulating strains wanes to approximately 50% of peak levels 3.5-7 years after infection in both age groups, and wanes faster against influenza A(H3N2) than A(H1N1)pdm09. Protection against H3N2 lasts longer in adults than in children. Our results suggest that the focus of influenza antibody responses changes over time from the highly mutable hemagglutinin head to other epitopes, consistent with the immunological theory of original antigenic sin, and that this change of focus might affect protection. Additionally, we estimate that imprinting, or primary infection with a subtype of one phylogenetic group, has little to no effect on the risk of non-medically attended influenza infections in adults. We also find no evidence of long-term cross-protection between subtypes. This work underscores the need for longitudinal data on multiple components of the immune response to better understand the development of immunity and differences in susceptibility within populations.

epidemiology↗
bioRxiv2018

Oral health-related quality of life in elderly women participating in a coexistence group in southern Brazil

The objective of this work was to evaluate the association between quality of life with the oral health in elderly women participating in a coexistence group in Southern Brazil. Study of the descriptive type, analytical, cross-sectional approach, with women aged 60 years or more, participants of a coexistence group in a city in Southern Brazil. Data collection used the instrument Oral Health Impact Profile (OHIP-14). The study had the participation of 64 elderly women aged between 60 and 88 years old with a mean of 69.8 {+/-} 7.31 years. The areas that presented the highest values were \"Physical Pain\", \"Psychological Distress\" and \"Physical Disability\". The highest averages of the total scores of the OHIP-14 occurred in individuals with lower family income and low education, who showed signs of depression, changes in taste, difficulty to feel the taste of certain foods and malnutrition. Low education, change of taste and malnutrition by the arm circumference were associated with poor quality of life arising from oral disorders.

epidemiology↗
bioRxiv2018

Effectiveness of Demand creation promotions and demand creation personnel in creating demand for Voluntary Medical Male Circumcision, Chitungwiza District, Zimbabwe in 2016

Zimbabwe is one of the 14 countries in eastern and southern Africa that have adopted Voluntary Medical Male Circumcision (VMMC) as an HIV prevention intervention in response to WHOs recommendation for countries with generalised high HIV epidemics and low VMMC prevalence. However, since 2013 when VMMC was scalled up in Zimbabwe, there was a general low uptake of the VMMC programme particularly on the target age group 20-29 years which has an immediate reduction in the HIV burden. The failure of VMMC uptake in the priority age group prompted the need to analyse the effectiveness of demand creation promotions and personnel used in creating demand for VMMC in Chitungwiza district, Zimbabwe. We employed judgmental sampling, a non-probability sampling technique where we interviewed VMMC clients (n=50) and service providers (n=10) using self administered questions, and community mobilisers (n=10) and demand creation teams (n=3) using face-to-face interviews based on their experience, knowledge and professional judgment. We also randomly analysed client records in the form of 50 Client Intake Forms (CIF) books. We found out that Community mobilisers and Demand creation officers were effective in mobilising clients in the age group 10-15 years and 16-30 years respectively. The use of clinicians (nurses) was also found to be useful in creating demand for VMMC. We also found out that intensifying campaigns during school holidays, the use of tent-based/caravan campaigns and the door to door campaigns were most effective strategies under demand creation promotions. We concluded that there is need to increase demand creation officers and qualified community mobilisers. To regulary train and motivate current community mobilisers as well as increasing the use of clinicians(nurses) in demand creation. We recommended the need to increase the number of mobile caravans and intensifying on the door to door campaigns in the district.

epidemiology↗