scholarly journals A graphical model for skewed matrix-variate non-randomly missing data

Biostatistics ◽  
2018 ◽  
Author(s):  
Lin Zhang ◽  
Dipankar Bandyopadhyay
Keyword(s):  
Mixed Model ◽  
Graphical Model ◽  
Linear Mixed Model ◽  
Disease Status ◽  
Epidemiological Studies ◽  
Model Parameters ◽  
Probit Regression ◽  
Pocket Depth ◽  
Cross Sectional ◽  
Missing Responses

SummaryEpidemiological studies on periodontal disease (PD) collect relevant bio-markers, such as the clinical attachment level (CAL) and the probed pocket depth (PPD), at pre-specified tooth sites clustered within a subject’s mouth, along with various other demographic and biological risk factors. Routine cross-sectional evaluation are conducted under a linear mixed model (LMM) framework with underlying normality assumptions on the random terms. However, a careful investigation reveals considerable non-normality manifested in those random terms, in the form of skewness and tail behavior. In addition, PD progression is hypothesized to be spatially-referenced, i.e. disease status at proximal tooth-sites may be different from distally located sites, and tooth missingness is non-random (or informative), given that the number and location of missing teeth informs about the periodontal health in that region. To mitigate these complexities, we consider a matrix-variate skew-$t$ formulation of the LMM with a Markov graphical embedding to handle the site-level spatial associations of the bivariate (PPD and CAL) responses. Within the same framework, the non-randomly missing responses are imputed via a latent probit regression of the missingness indicator over the responses. Our hierarchical Bayesian framework powered by relevant Markov chain Monte Carlo steps addresses the aforementioned complexities within an unified paradigm, and estimates model parameters with seamless sharing of information across various stages of the hierarchy. Using both synthetic and real clinical data assessing PD status, we demonstrate a significantly improved fit of our proposition over various other alternative models.

scholarly journals 103 Periodontal Health and Sarcopenia: Cross-Sectional Evidence From A Cohort of 2040 Twin Volunteers

2021 ◽  
Vol 50 (Supplement_1) ◽  
pp. i12-i42
Author(s):  
M B Zazzara ◽  
P M Wells ◽  
R C E Bowyer ◽  
M N Lochlainn ◽  
E J Thompson ◽  
...  
Keyword(s):  
Mixed Model ◽  
Linear Mixed Model ◽  
Frailty Index ◽  
Muscle Quality ◽  
Low Grade ◽  
Periodontal Health ◽  
Cross Sectional ◽  
Age Related ◽  
European Working ◽  
Generalised Linear Mixed Model

Abstract Introduction Periodontitis is a chronic inflammatory disease affecting the periodontium, ultimately leading to looseness and/or loss of teeth. Sarcopenia refers to age-related reduction in muscle mass and strength. Similar to periodontitis, chronic low-grade inflammation is thought to play a key role in its development. In addition, both increase in prevalence with advancing age. Despite known associations with other diseases involving a dysregulated inflammatory response, for example rheumatoid arthritis,, the relationship between periodontitis and sarcopenia, and whether they could be driven by similar processes, remains uncertain. The aim of this study was to explore the association between periodontitis and sarcopenia. Methods Observational study of 2040 adult volunteers [age 67.18 (12.17)] enrolled in the TwinsUK cohort study. Presence of tooth mobility and number of teeth lost were used to assess periodontal health. A binary variable was created to define periodontitis. Measurements of muscle strength, muscle quality/quantity and physical performance were used to assess sarcopenia. A categorical variable was created according to the European Working Group on Sarcopenia in Older People (EWGSOP2) consensus, to define sarcopenia (1: probable; 2: positive; 3: severe). Generalised linear mixed model analysis used on complete cases and age-matched (n = 1,288) samples to ascertain associations between periodontitis and sarcopenia. Results No significant association was found between periodontitis and sarcopenia in both the complete cases analysis and age-matched analysis. Results were consistent when analysis was adjusted for potential confounders including body mass index, frailty index, Mini Mental State Examination smoking, nutritional status and educational level. Conclusions This study found no significant association between periodontitis and sarcopenia in a cohort of 2040 adults. Although both periodontitis and sarcopenia have been linked to a dysregulated immune response and demonstrate an increase in prevalence with increasing age, our work is inconclusive due to the plethora of possible aetiopathogenetic pathways.

scholarly journals The association of socio-demographic and environmental factors on childhood diarrhea in Cambodia

F1000Research ◽  
2020 ◽  
Vol 9 ◽  
pp. 303
Author(s):  
Vong Pisey ◽  
Pannee Banchonhattakit
Keyword(s):  
Maternal Age ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Secondary Data ◽  
Cross Sectional Study ◽  
Health Concern ◽  
Childhood Diarrhea ◽  
Public Health Concern ◽  
Cross Sectional ◽  
One Year

Background: Diarrhea is still the leading cause of childhood death worldwide, as well as a major cause for concern in developing countries. This study was conducted to investigate the factors related to childhood diarrhea in Cambodia. Methods: A cross-sectional study of the secondary data from the Cambodia Demographic and Health Survey 2014 was conducted using the combination of household data and children’s data. A generalized linear mixed model was used to analyze the determinant factors of childhood diarrhea. Results: The surveys included 2,828 children, aged 12 to 35 months. The prevalence of diarrhea in the last 2 weeks was 16.44% (95% CI: 14.72%-18.31%). Factors with statistically significant associations with childhood diarrhea in Cambodia were: maternal  unemployment, compared with being in employment (AOR = 1.43; 95% CI: 1.14-1.78); the child being male (AOR = 1.25; 95%CI: 1.02-1.53); the presence of unimproved toilet facilities (AOR = 1.17; 95%CI: 1.05-1.31) compared with improved toilet facilities; and unhygienic disposal of children’s stools (AOR = 1.32; 95%CI: 1.06-1.64) compared with hygienic disposal of children’s stools when controlling for other covariates. Both maternal age (one year older; AOR = 0.85; 95%CI: 0.78– 0.93) and child age (one month older; AOR = 0.86; 95%CI: 0.78-0.94) had significant negative associations with the occurrence of childhood diarrhea. Conclusion: Childhood diarrhea remains a public health concern in Cambodia. The probability of diarrhea occurring is shown to be increased by maternal unemployment, the sex of the child being male, lack of provision of improved toilet facilities, and the unhygienic disposal of children’s stools; whereas increasing maternal age and child’s age were associated with a reduced chance of diarrhea occurring. On the basis of these results, we recommend provision of programs focusing on reducing diarrhea through the construction of improved toilet facilities and the promotion of behavior to improve hygiene, specifically targeting younger mothers.

scholarly journals Subjective Well-Being in Early Adolescence: Observations from a Five-Year Longitudinal Study

2020 ◽  
Vol 17 (21) ◽  
pp. 8249
Author(s):  
Mònica González-Carrasco ◽  
Marc Sáez ◽  
Ferran Casas
Keyword(s):  
Data Collection ◽  
Longitudinal Studies ◽  
Early Adolescence ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Well Being ◽  
Subjective Well Being ◽  
Cross Sectional ◽  
Additional Information ◽  
Stage Of Development

This article aims to redress the lack of longitudinal studies on adolescents’ subjective well-being (SWB) and highlight the relevance of knowledge deriving from such research in designing public policies for improving their health and wellbeing in accordance with the stage of development they are in. To achieve this, the evolution of SWB during early adolescence (in adolescents aged between 10 and 14 in the first data collection) was explored over a five year period, considering boys and girls together and separately. This involved comparing different SWB scales and contrasting results when considering the year of data collection versus the cohort (year of birth) participants belonged to. The methodology comprised a generalized linear mixed model using the INLA (Integrated Nested Laplace Approximation) estimation within a Bayesian framework. Results support the existence of a decreasing-with-age trend, which has been previously intuited in cross-sectional studies and observed in only a few longitudinal studies and contrasts with the increasing-with-age tendency observed in late adolescence. This decrease is also found to be more pronounced for girls, with relevant differences found between instruments. The decreasing-with-age trend observed when the year of data collection is taken into account is also observed when considering the cohort, but the latter provides additional information. The results obtained suggest that there is a need to continue studying the evolution of SWB in early adolescence with samples from other cultures; this, in turn, will make it possible to establish the extent to which the observed decreasing-with-age trend among early adolescents is influenced by cultural factors.

scholarly journals Characterizing Heterogeneity of Disease Incidence in a Spatial Hierarchy: A Case Study from a Decade of Observations of Fusarium Head Blight of Wheat

2012 ◽  
Vol 102 (9) ◽  
pp. 867-877 ◽  
Author(s):  
A. B. Kriss ◽  
P. A. Paul ◽  
L. V. Madden
Keyword(s):  
Spatial Heterogeneity ◽  
Fusarium Head Blight ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Disease Incidence ◽  
Geographical Location ◽  
Disease Status ◽  
Link Function ◽  
Head Blight ◽  
Growing Seasons

A multilevel analysis of heterogeneity of disease incidence was conducted based on observations of Fusarium head blight (caused by Fusarium graminearum) in Ohio during the 2002–11 growing seasons. Sampling consisted of counting the number of diseased and healthy wheat spikes per 0.3 m of row at 10 sites (about 30 m apart) in a total of 67 to 159 sampled fields in 12 to 32 sampled counties per year. Incidence was then determined as the proportion of diseased spikes at each site. Spatial heterogeneity of incidence among counties, fields within counties, and sites within fields and counties was characterized by fitting a generalized linear mixed model to the data, using a complementary log-log link function, with the assumption that the disease status of spikes was binomially distributed conditional on the effects of county, field, and site. Based on the estimated variance terms, there was highly significant spatial heterogeneity among counties and among fields within counties each year; magnitude of the estimated variances was similar for counties and fields. The lowest level of heterogeneity was among sites within fields, and the site variance was either 0 or not significantly greater than 0 in 3 of the 10 years. Based on the variances, the intracluster correlation of disease status of spikes within sites indicated that spikes from the same site were somewhat more likely to share the same disease status relative to spikes from other sites, fields, or counties. The estimated best linear unbiased predictor (EBLUP) for each county was determined, showing large differences across the state in disease incidence (as represented by the link function of the estimated probability that a spike was diseased) but no consistency between years for the different counties. The effects of geographical location, corn and wheat acreage per county, and environmental conditions on the EBLUP for each county were not significant in the majority of years.

Stressful life events and leukocyte telomere attrition in adulthood: a prospective population-based cohort study

2015 ◽  
Vol 45 (14) ◽  
pp. 2975-2984 ◽  
Author(s):  
S. L. van Ockenburg ◽  
E. H. Bos ◽  
P. de Jonge ◽  
P. van der Harst ◽  
R. O. B. Gans ◽  
...  
Keyword(s):  
Life Events ◽  
Mixed Model ◽  
Stressful Life Events ◽  
Linear Mixed Model ◽  
Smoking Status ◽  
Population Based ◽  
Adverse Life Events ◽  
Cross Sectional ◽  
Telomere Attrition ◽  
Multivariable Regression

Background.Telomere attrition might be one of the mechanisms through which psychosocial stress leads to somatic disease. To date it is unknown if exposure to adverse life events in adulthood is associated with telomere shortening prospectively. In the current study we investigated whether life events are associated with shortening of telomere length (TL).Method.Participants were 1094 adults (mean age 53.1, range 33–79 years) from the PREVEND cohort. Data were collected at baseline (T1) and at two follow-up visits after 4 years (T2) and 6 years (T3). Life events were assessed with an adjusted version of the List of Threatening Events (LTE). TL was measured by monochrome multiplex quantitative PCR at T1, T2, and T3. A linear mixed model was used to assess the effect of recent life events on TL prospectively. Multivariable regression analyses were performed to assess whether the lifetime life events score or the score of life events experienced before the age of 12 predicted TL cross-sectionally. All final models were adjusted for age, sex, body mass index, presence of chronic diseases, frequency of sports, smoking status, and level of education.Results.Recent life events significantly predicted telomere attrition prospectively (B = −0.031, p = 0.007). We were not able to demonstrate a significant cross-sectional relationship between the lifetime LTE score and TL. Nor did we find exposure to adverse life events before the age of 12 to be associated with TL in adulthood.Conclusions.Exposure to recent adverse life events in adulthood is associated with telomere attrition prospectively.

Edinburgh Vein Study: Methods and Response in a Survey of Venous Disease in the General Population

1997 ◽  
Vol 12 (4) ◽  
pp. 127-135 ◽  
Author(s):  
C J. Evans ◽  
F. G. R. Fowkes ◽  
C. V. Ruckley ◽  
P. L. Allan ◽  
M. N. Carson ◽  
...  
Keyword(s):  
General Population ◽  
Response Rate ◽  
Venous Blood ◽  
Disease Status ◽  
Epidemiological Studies ◽  
Ethnic Origin ◽  
Cross Sectional Study ◽  
Venous Disease ◽  
Cross Sectional ◽  
Study Participants

Objective: To describe the methods required to conduct a large epidemiological study of venous disease in the general population, and the resulting response. Design: Cross-sectional study. Setting: University of Edinburgh. Participants: Men and women aged 18–64 years, randomly selected from general practice registers. Methods: Subjects were invited for the following procedures: questionnaire, height and weight measurement, classification of varices and chronic venous insufficiency, duplex measurement of duration of venous reflux and venous blood sampling. A questionnaire survey of non-responders was carried out. Results of response: A total of 1566 subjects attended, a final response rate of 53.8%. The response rate increased with age. The distribution of ethnic origin and social class of attenders was similar to that of the general Edinburgh population. Study participants were generally older, from more affluent areas and more often female than non-responders ( p ≤ 0.001). Conclusions: Large epidemiological studies of venous disease in the community are feasible but the level of response illustrates the importance of obtaining information on the disease status of non-responders.

scholarly journals Factors Related to Serum Lipids Using Multilevel Quantile Mixed Model:  Analysis of Nationwide STEPs Survey 2016

2021 ◽  
Author(s):  
Parisa Mohseni ◽  
Davood Khalili ◽  
Shirin Djalalinia ◽  
Farshad Farzadfar ◽  
Yadollah Mehrabi
Keyword(s):  
Serum Lipids ◽  
Mixed Model ◽  
Communicable Disease ◽  
Random Effect ◽  
Vascular Diseases ◽  
Model Parameters ◽  
Lipid Levels ◽  
Related Factors ◽  
Cross Sectional ◽  
Mixed Model Analysis

Abstract Backgroundlipid disorder is a modifiable risk factor for diseases related to plaque formation in arteries such as heart attack, stroke and peripheral vascular diseases. Identifying related factors and diagnosis and treatment in time reduces the incidence of non - communicable diseases. The aim of this study was to determine factors associated with lipids based on a national survey data.MethodsData of 16757 individuals aged 25–64 years obtained from the Iranian national cross-sectional study of the risk factors of non-Communicable disease (STEPs) performed in 2016, through multi-stage random sampling, were analyzed. Because of clustered, hierarchical and skewed form of the data, factors related to total Cholesterol (TC), Triglycerides (TG), LDL-C, HDL-C, TG/HDL-C, TC/HDL-C, LDL-C/HDL-C were determined applying multilevel quantile mixed model. Parameters of the model were estimated on the basis of random effect of the province as well as urban or rural area for 10th, 25th, 50th, 75th and 90th quantiles. Statistical analyses were performed by R software version 4.0.2.ResultsSignificant relationship was found between age, BMI, waist circumference, diabetes, hypertension, smoking, physical activity, education level, and marital status with TC, LDL-C, HDL-C, LDL-C and LDL-C/HDL-C. With increasing BMI and WC, subjects had higher levels of serum lipids, especially in higher quantiles of lipid levels. Lipid levels were significantly increased among smokers and those with diabetes or hypertension. The random effects were also significant showing that there is a correlation between the level of lipids in provincial habitants as well as urban and rural areas.ConclusionThis study showed that the effect of each factor varies depending on the centiles of the lipids. Significant relationship was found between sociodemographic, Behaviors and anthropometric indices with lipid parameters.

scholarly journals Spatial Modeling of Depression and Its Related Factors Using a Spatial Generalized Linear Mixed Model in Mashhad, Iran: A Cross-Sectional Study

2019 ◽  
Vol 20 (11) ◽  
Author(s):  
Ali Hadianfar ◽  
Habibollah Esmaily ◽  
Majid Ghayour-Mobarhan ◽  
Hossein Aghajani ◽  
Azadeh Saki ◽  
...  
Keyword(s):  
Spatial Modeling ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Generalized Linear Mixed Model ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Related Factors ◽  
Cross Sectional

scholarly journals Modelling for Anaemia and Malnutrition in Children Less Than Five Years of Age in Lesotho: A Case Study of a Cross-Sectional Dataset Using Multivariate Joint Model.

2021 ◽  
Author(s):  
Rugiranka Tony Gaston ◽  
Shaun Ramroop ◽  
Faustin Habyarimana
Keyword(s):  
Mixed Model ◽  
Linear Mixed Model ◽  
Strong Association ◽  
Care Facility ◽  
Wealth Index ◽  
Strong Relationship ◽  
Joint Model ◽  
Primary Objective ◽  
Malnourished Child ◽  
Cross Sectional

Abstract Background Anaemia and malnutrition remain jointly a serious health issue worldwide especially in developing countries. In Lesotho, the prevalence of anaemia and malnutrition remains highly significant especially among children less than five years of age. Objectives The primary objective of the present study was to determine the association between anaemia and malnutrition, and identify the associated factors with the two diseases among children less than five years of age in Lesotho. Methods The present study was cross-sectional and used secondary data from the 2014 Lesotho Demographic Health Survey (LDHS). The study considered a total number of 3112 children and utilized a multivariate joint model under the scope of the generalized linear mixed model (GLMM) for the data analysis. Results The prevalence of anaemia and stunting in children less than five years of age were 51% and 43% respectively. The multivariate results revealed that there is a strong relationship between anaemia and malnutrition. In addition, the results indicated that education, residence, wealth index and childbirth weight have a significant effect on stunted or malnourished child, while child with fever and diarrhoea have a significant effect on anaemia. Lastly, child’s age has a significant effect on both stunting and anaemia. Conclusion The study indicated a strong association between anaemia and stunting or malnutrition in the long-term, and controlling one disease should result in reducing the other. The socio-economic, geographical and demographic variables have a significant impact on improving stunting and anaemia. Thus, improving nutrition in children less than five years, especially those from rural area and having a birthweight less than 2500g, and educating the mothers to take their children to the health care facility when they have fever and diarrhoea, especially those from poor background, would contribute immensely to the reduction of malnutrition and anaemia in children from Lesotho.

scholarly journals The association of socio-demographic and environmental factors on childhood diarrhea in Cambodia

F1000Research ◽  
2021 ◽  
Vol 9 ◽  
pp. 303
Author(s):  
Vong Pisey ◽  
Pannee Banchonhattakit ◽  
Wongsa Laohasiriwong
Keyword(s):  
Maternal Age ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Secondary Data ◽  
Cross Sectional Study ◽  
Health Concern ◽  
Childhood Diarrhea ◽  
Public Health Concern ◽  
Cross Sectional ◽  
One Year

Background:Diarrhea is still the leading cause of childhood death worldwide, as well as a major cause for concern in developing countries. This study was conducted to investigate the factors related to childhood diarrhea in Cambodia. Methods:A cross-sectional study of the secondary data from the Cambodia Demographic and Health Survey 2014 was conducted using the combined dataset of household data and children’s data. A generalized linear mixed model was used to analyze the determinant factors of childhood diarrhea. Results:The surveys included 2,828 children, aged 12 to 35 months. The prevalence of diarrhea in the last 2 weeks was 16.44% (95% CI: 14.72%-18.31%). Factors with statistically significant associations with childhood diarrhea in Cambodia were: maternal unemployment, compared with being in employment (AOR = 1.43; 95% CI: 1.14-1.78); the child being male (AOR = 1.25; 95%CI: 1.02-1.53); the presence of unimproved toilet facilities (AOR = 1.17; 95%CI: 1.05-1.31) compared with improved toilet facilities; and unhygienic disposal of children’s stools (AOR = 1.32; 95%CI: 1.06-1.64) compared with hygienic disposal of children’s stools when controlling for other covariates. Both maternal age (one year older; AOR = 0.85; 95%CI: 0.78– 0.93) and child age (one month older; AOR = 0.86; 95%CI: 0.78-0.94) had significant negative associations with the occurrence of childhood diarrhea. Conclusion:Childhood diarrhea remains a public health concern in Cambodia. The probability of diarrhea occurring is shown to be increased by maternal unemployment, the sex of the child being male, lack of provision of improved toilet facilities, and the unhygienic disposal of children’s stools; whereas increasing maternal age and child’s age were associated with a reduced chance of diarrhea occurring. On the basis of these results, we recommend provision of programs focusing on reducing diarrhea through the construction of improved toilet facilities and the promotion of behavior to improve hygiene, specifically targeting younger mothers.

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