scholarly journals Per-partnership transmission probabilities for Chlamydia trachomatis infection: evidence synthesis of population-based survey data

2020 ◽  
Author(s):  
Joanna Lewis ◽  
Peter J White ◽  
Malcolm J Price
Keyword(s):  
Evidence Synthesis ◽  
Credible Interval ◽  
Transmission Probability ◽  
Monte Carlo Sampling ◽  
Population Based ◽  
Control Measures ◽  
Chlamydia Infection ◽  
National Study ◽  
Transmitted Infection ◽  
Chlamydia Trachomatis Infection

Abstract Background Chlamydia is the most commonly diagnosed sexually transmitted infection worldwide. Mathematical models used to plan and assess control measures rely on accurate estimates of chlamydia’s natural history, including the probability of transmission within a partnership. Several methods for estimating transmission probability have been proposed, but all have limitations. Methods We have developed a new model for estimating per-partnership chlamydia transmission probabilities from infected to uninfected individuals, using data from population-based surveys. We used data on sexual behaviour and prevalent chlamydia infection from the second UK National Study of Sexual Attitudes and Lifestyles (Natsal-2) and the US National Health and Nutrition Examination Surveys 2009–2014 (NHANES) for Bayesian inference of average transmission probabilities, across all new heterosexual partnerships reported. Posterior distributions were estimated by Markov chain Monte Carlo sampling using the Stan software. Results Posterior median male-to-female transmission probabilities per partnership were 32.1% [95% credible interval (CrI) 18.4–55.9%] (Natsal-2) and 34.9% (95%CrI 22.6–54.9%) (NHANES). Female-to-male transmission probabilities were 21.4% (95%CrI 5.1–67.0%) (Natsal-2) and 4.6% (95%CrI 1.0–13.1%) (NHANES). Posterior predictive checks indicated a well-specified model, although there was some discrepancy between reported and predicted numbers of partners, especially in women. Conclusions The model provides statistically rigorous estimates of per-partnership transmission probability, with associated uncertainty, which is crucial for modelling and understanding chlamydia epidemiology and control. Our estimates incorporate data from several sources, including population-based surveys, and use information contained in the correlation between number of partners and the probability of chlamydia infection. The evidence synthesis approach means that it is easy to include further data as it becomes available.

scholarly journals Investigating the effects of accelerated partner therapy (APT) on chlamydia transmission in Britain: a mathematical modelling study

2020 ◽  
Author(s):  
Christian L Althaus ◽  
Catherine H Mercer ◽  
Jackie A Cassell ◽  
Claudia S Estcourt ◽  
Nicola Low
Keyword(s):  
Sexual Activity ◽  
Control Strategies ◽  
Controlled Trial ◽  
Partner Notification ◽  
Cluster Randomised Controlled Trial ◽  
Credible Interval ◽  
Population Based ◽  
Transmission Model ◽  
Transmitted Infection ◽  
Potential Increase

Understanding the effects of partner notification (PN) on the transmission of chlamydia, the most prevalent bacterial sexual transmitted infection worldwide, is critical for implementing optimal control strategies. Accelerated partner therapy (APT) aims to increase the numbers of partners treated and reduce the time to partner treatment. Our objective was to study the effects of APT interventions on partner treatment and chlamydia transmission in order to better understand the results of LUSTRUM, an APT cross-over cluster randomised controlled trial in the UK. We developed a novel deterministic, population-based chlamydia transmission model including the process of PN. We considered a population aged 16-34 years and calibrated the model to sexual behaviour data between people of the opposite-sex and chlamydia prevalence data reported by 3,671 participants in Britain's third National Survey of Sexual Attitudes and Lifestyles (Natsal-3, 2010-2012) using Approximate Bayesian Computation (ABC). We investigated the potential effects of APT on chlamydia transmission by increasing the number of treated partners and reducing the time to partner treatment compared to standard PN. The median prevalence of chlamydia in the model was 1.84% (95% credible interval, CrI: 1.60%-2.62%) in women and 1.78% (95% CrI: 1.13%-2.14%) in men. Chlamydia positivity was highest in partners of symptomatic index cases with low sexual activity. Infected partners were typically asymptomatic and belonged to the high sexual activity group, i.e., are naturally those infected individuals that will contribute most to onward transmission. Reducing the time to partner treatment without achieving higher numbers of partners treated had only minor effects on reducing chlamydia prevalence. In contrast, the model predicts that a potential increase in the number of partners treated from current levels in Britain (0.51, 95% CrI: 0.21-0.80) by 25% would reduce chlamydia prevalence by 18% (95% CrI: 5%-44%) in both women in men within 5 years. These results suggest that APT, through a potential increase in the proportion of partners treated, would be an effective method to reduce ongoing chlamydia transmission in Britain.

scholarly journals Discrepancies between observed data and predictions from mathematical modelling of the impact of screening interventions onChlamydia trachomatisprevalence

2018 ◽  
Author(s):  
Joost Smid ◽  
Christian L. Althaus ◽  
Nicola Low
Keyword(s):  
Mathematical Modelling ◽  
Natural Infection ◽  
Credible Interval ◽  
Population Based ◽  
Chlamydia Infection ◽  
Infected People ◽  
Modelling Studies ◽  
The Impact ◽  
Over Time ◽  
Partial Immunity

Mathematical modelling studies ofC. trachomatistransmission predict that interventions to screen and treat chlamydia infection will reduce prevalence to a greater degree than that observed in empirical population-based studies. We investigated two factors that might explain this discrepancy: partial immunity after natural infection clearance and differential screening coverage according to infection risk. We used four variants of a compartmental model for heterosexualC. trachomatistransmission, parameterized using data from England about sexual behaviour andC. trachomatistesting, diagnosis and prevalence, and Markov Chain Monte Carlo methods for statistical inference. A model in which partial immunity follows natural infection clearance and the proportion of tests done in chlamydia-infected people decreases over time fitted the data best. The model predicts that partial immunity reduced susceptibility to reinfection by 72% (95% Bayesian credible interval 57-86%). The estimated screening rate was 4.6 (2.6-6.5) times higher for infected than for uninfected women in 2000; this decreased to 2.1 (1.4-2.9) in 2011. Other factors not included in the model could have further reduced the expected impact of screening. Future mathematical modelling studies investigating the effects of screening interventions onC. trachomatistransmission should incorporate host immunity and changes over time in the targeting of screening.

The Oxford Handbook of Integrative Health Science

2018 ◽  
Keyword(s):  
Adult Life ◽  
The United States ◽  
Sociodemographic Factors ◽  
Population Based ◽  
Health Science ◽  
National Study ◽  
Integrative Health ◽  
Social Structural ◽  
Research Population ◽  
Psychosocial Influences

This handbook signals a paradigm shift in health research. Population-based disciplines have employed large national samples to examine how sociodemographic factors contour rates of morbidity and mortality. Behavioral and psychosocial disciplines have studied the factors that influence these domains using small, nonrepresentative samples in experimental or longitudinal contexts. Biomedical disciplines, drawing on diverse fields, have examined mechanistic processes implicated in disease outcomes. The collection of chapters in this handbook embraces all such prior approaches and, via targeted questions, illustrates how they can be woven together. Diverse contributions showcase how social structural influences work together with psychosocial influences or experiential factors to impact differing health outcomes, including profiles of biological risk across distinct physiological systems. These varied biopsychosocial advances have grown up around the Midlife in the United States (MIDUS) national study of health, begun over 20 years ago and now encompassing over 12,000 Americans followed through time. The overarching principle behind the MIDUS enterprise is that deeper understanding of why some individuals remain healthy and well as they move across the decades of adult life, while others succumb to differing varieties of disease, dysfunction, or disability, requires a commitment to comprehensiveness that attends to the interplay of multiple interacting influences. Put another way, all of the disciplines mentioned have reliably documented influences on health, but in and of themselves, each is inherently limited because it neglects factors known to matter for health outside the discipline’s purview. Integrative health science is the alternative seeking to overcome these limitations.

Long-Term Exposure to PM2.5 and Cognitive Decline: A Longitudinal Population-Based Study

2021 ◽  
pp. 1-9
Author(s):  
Giulia Grande ◽  
Jing Wu ◽  
Petter L.S. Ljungman ◽  
Massimo Stafoggia ◽  
Tom Bellander ◽  
...  
Keyword(s):  
Air Pollution ◽  
Cognitive Decline ◽  
Population Based ◽  
Cerebrovascular Diseases ◽  
Air Pollutant ◽  
National Study ◽  
Piecewise Regression ◽  
Risk Increase ◽  
Restricted Cubic Splines

Background: A growing but contrasting evidence relates air pollution to cognitive decline. The role of cerebrovascular diseases in amplifying this risk is unclear. Objectives: 1) Investigate the association between long-term exposure to air pollution and cognitive decline; 2) Test whether cerebrovascular diseases amplify this association. Methods: We examined 2,253 participants of the Swedish National study on Aging and Care in Kungsholmen (SNAC-K). One major air pollutant (particulate matter ≤2.5μm, PM2.5) was assessed yearly from 1990, using dispersion models for outdoor levels at residential addresses. The speed of cognitive decline (Mini-Mental State Examination, MMSE) was estimated as the rate of MMSE decline (linear mixed models) and further dichotomized into the upper (25%fastest cognitive decline), versus the three lower quartiles. The cognitive scores were used to calculate the odds of fast cognitive decline per levels of PM2.5 using regression models and considering linear and restricted cubic splines of 10 years exposure before the baseline. The potential modifier effect of cerebrovascular diseases was tested by adding an interaction term in the model. Results: We observed an inverted U-shape relationship between PM2.5 and cognitive decline. The multi-adjusted piecewise regression model showed an increased OR of fast cognitive decline of 81%(95%CI = 1.2–3.2) per interquartile range difference up to mean PM2.5 level (8.6μg/m3) for individuals older than 80. Above such level we observed no further risk increase (OR = 0.89;95%CI = 0.74–1.06). The presence of cerebrovascular diseases further increased such risk by 6%. Conclusion: Low to mean PM2.5 levels were associated with higher risk of accelerated cognitive decline. Cerebrovascular diseases further amplified such risk.

scholarly journals MiR-378b Modulates Chlamydia-Induced Upper Genital Tract Pathology

Pathogens ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 566
Author(s):  
Stephanie R. Lundy ◽  
Kobe Abney ◽  
Debra Ellerson ◽  
Joseph U. Igietseme ◽  
Darin Carroll ◽  
...  
Keyword(s):  
Host Responses ◽  
Chlamydia Infection ◽  
Chlamydia Trachomatis Infection ◽  
Host Immune Responses ◽  
Tubal Factor Infertility ◽  
Evolutionarily Conserved ◽  
Duration Of Infection ◽  
Tubal Factor ◽  
Pathologic Lesions ◽  
Mammalian Gene Expression

Genital Chlamydia trachomatis infection causes severe reproductive pathologies such as salpingitis and pelvic inflammatory disease that can lead to tubal factor infertility. MicroRNAs (miRNAs) are evolutionarily conserved regulators of mammalian gene expression in development, immunity and pathophysiologic processes during inflammation and infection, including Chlamydia infection. Among the miRNAs involved in regulating host responses and pathologic outcome of Chlamydia infection, we have shown that miR-378b was significantly differentially expressed during primary infection and reinfection. In this study, we tested the hypothesis that miR-378b is involved in the pathological outcome of Chlamydia infection. We developed miR-378b knockout mice (miR-378b−/−) using Crispr/Cas and infected them along with their wild-type (WT) control with Chlamydia to compare the infectivity and reproductive pathologies. The results showed that miR-378b−/− mice were unable to clear the infection compared to WT mice; also, miR-378b−/− mice exhibited a relatively higher Chlamydia burden throughout the duration of infection. However, gross pathology results showed that miR-378b−/− mice had significantly reduced uterine dilatations and pathologic lesions after two infections compared to WT mice. In addition, the pregnancy and fertility rates for infected miR-378b−/− mice showed protection from Chlamydia-induced infertility with fertility rate that was comparable to uninfected WT mice. These results are intriguing as they suggest that miR-378b is important in regulating host immune responses that control Chlamydial replication and drive the inflammation that causes complications such as infertility. The finding has important implications for biomarkers of Chlamydial complications and targets for prevention of disease.

Epidemiology and risk of psychiatric disorders among patients with celiac disease: A population‐based national study

2021 ◽  
Author(s):  
Motasem Alkhayyat ◽  
Thabet Qapaja ◽  
Manik Aggarwal ◽  
Ashraf Almomani ◽  
Mohammad Abureesh ◽  
...  
Keyword(s):  
Celiac Disease ◽  
Psychiatric Disorders ◽  
Population Based ◽  
National Study

scholarly journals Frailty Changes Predict Mortality in 4 Longitudinal Studies of Aging

2020 ◽  
Author(s):  
Erwin Stolz ◽  
Emiel O Hoogendijk ◽  
Hannes Mayerl ◽  
Wolfgang Freidl
Keyword(s):  
Mortality Risk ◽  
Clinical Decision Making ◽  
Frailty Index ◽  
Credible Interval ◽  
Clinical Decision ◽  
Population Based ◽  
Time To Event Data ◽  
Longitudinal Aging Study Amsterdam ◽  
Aging Study ◽  
Longitudinal Aging Study

Abstract Background Baseline frailty index (FI) values have been shown to predict mortality among older adults, but little is known about the effects of changes in FI on mortality. Methods In a coordinated approach, we analyzed data from 4 population-based cohorts: the Health and Retirement Study (HRS), the Survey of Health, Ageing and Retirement in Europe (SHARE), the English Longitudinal Survey of Ageing (ELSA), and the Longitudinal Aging Study Amsterdam (LASA), comprising a total of 24 961 respondents (65+), 95 897 observations, up to 9 repeated FI assessments, and up to 23 years of mortality follow-up. The effect of time-varying FI on mortality was modeled with joint regression models for longitudinal and time-to-event data. Results Differences (of 0.01) in current FI levels (hazard ratio [HR] = 1.04, 95% credible interval [CI] = 1.03–1.05) and baseline FI levels (HR = 1.03, 95% CI = 1.03–1.05) were consistently associated with mortality across studies. Importantly, individuals with steeper FI growth also had a higher mortality risk: An increase in annual FI growth by 0.01 was associated with an increased mortality risk of HR = 1.56 (95% CI = 1.49–1.63) in HRS, HR = 1.24 (95% CI = 1.13–1.35) in SHARE, HR = 1.40 (95% CI = 1.25–1.52) in ELSA, and HR = 1.71 (95% CI = 1.46–2.01) in LASA. Conclusions FI changes predicted mortality independently of baseline FI differences. Repeated assessment of frailty and individual’s frailty trajectory could provide a means to anticipate further health deterioration and mortality and could thus support clinical decision making.

Global epidemiology of SARS-CoV-2 infection: a systematic review and meta-analysis of standardized population-based seroprevalence studies, Jan 2020-Oct 2021

2021 ◽  
Author(s):  
Isabel Bergeri ◽  
Mairead Whelan ◽  
Harriet Ware ◽  
Lorenzo Subissi ◽  
Anthony Nardone ◽  
...  
Keyword(s):  
Systematic Review ◽  
Meta Analysis ◽  
Grey Literature ◽  
Population Based ◽  
Control Measures ◽  
Middle Income ◽  
Global Epidemiology ◽  
Using Data ◽  
Demographic Subgroups ◽  
Over Time

Background COVID-19 case data underestimates infection and immunity, especially in low- and middle-income countries (LMICs). We meta-analyzed standardized SARS-CoV-2 seroprevalence studies to estimate global seroprevalence. Objectives/Methods We conducted a systematic review and meta-analysis, searching MEDLINE, Embase, Web of Science, preprints, and grey literature for SARS-CoV-2 seroprevalence studies aligned with the WHO UNITY protocol published between 2020-01-01 and 2021-10-29. Eligible studies were extracted and critically appraised in duplicate. We meta-analyzed seroprevalence by country and month, pooling to estimate regional and global seroprevalence over time; compared seroprevalence from infection to confirmed cases to estimate under-ascertainment; meta-analyzed differences in seroprevalence between demographic subgroups; and identified national factors associated with seroprevalence using meta-regression. PROSPERO: CRD42020183634. Results We identified 396 full texts reporting 736 distinct seroprevalence studies (41% LMIC), including 355 low/moderate risk of bias studies with national/sub-national scope in further analysis. By April 2021, global SARS-CoV-2 seroprevalence was 26.1%, 95% CI [24.6-27.6%]. Seroprevalence rose steeply in the first half of 2021 due to infection in some regions (e.g., 18.2% to 45.9% in Africa) and vaccination and infection in others (e.g., 11.3% to 57.4% in the Americas high-income countries), but remained low in others (e.g., 0.3% to 1.6% in the Western Pacific). In 2021 Q1, median seroprevalence to case ratios were 1.9:1 in HICs and 61.9:1 in LMICs. Children 0-9 years and adults 60+ were at lower risk of seropositivity than adults 20-29. In a multivariate model using data pre-vaccination, more stringent public health and social measures were associated with lower seroprevalence. Conclusions Global seroprevalence has risen considerably over time and with regional variation, however much of the global population remains susceptible to SARS-CoV-2 infection. True infections far exceed reported COVID-19 cases. Standardized seroprevalence studies are essential to inform COVID-19 control measures, particularly in resource-limited regions.

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