Review and recommendations for zero-inflated count regression modeling of dental caries indices in epidemiological studies

Caries Incidence and Its Associated Factors in Hong Kong Kindergarten Children

OBJECTIVE

The study aimed to investigate caries incidence and its associate factors among kindergarten children in Hong Kong.

METHOD

This 30-month prospective study recruited 3- to 4-year-old children when they started their kindergarten study. A self-administered parental questionnaire survey was used to collect the children's social demographic information and their oral health-related habits. Child's caries experience was recorded using the decayed, missing, and filled tooth (dmft) index and the visible plaque index (VPI) was used to measure their oral hygiene status. A final examination was performed after 30 months when they were in the final year of kindergarten. Data were analysed using the zero-inflated negative binomial (ZINB) regression model.

RESULTS

This study examined 660 children at baseline and 501 children at the final examination (dropout 24%). At baseline, the caries prevalence among 501 children was 23%, with mean (SD) dmft scores of 0.7 (1.8). At the final examination, caries prevalence increased to 41%, with mean (SD) dmft scores of 1.6 (2.8). The 30-month incidence rate was 34%, and the mean (SD) number of new carious teeth developed was 0.9 (1.7). Lower first molars exhibited the highest caries increment rate (11%), followed by upper second molars (9%) and upper central incisors (9%). ZINB regression analysis revealed associations among caries incidence and family income, baseline dmft, and baseline VPI (P < .05).

CONCLUSIONS

One third of Hong Kong kindergarten children developed new caries. Low family income, prior caries experience and poor oral hygiene were the significant factors associated with their caries incidence.

CLINICAL RELEVANCE

Many children developed new caries during their kindergarten years, with their caries experience more than doubling. Preventive measures, including oral health education and reinforcing oral hygiene practice in kindergarten, are essential to reduce their caries incidence, particularly for children with low family income, caries experience and poor oral hygiene.

Population-average mediation analysis for zero-inflated count outcomes

Mediation analysis is an increasingly popular statistical method for explaining causal pathways to inform intervention. While methods have increased, there is still a dearth of robust mediation methods for count outcomes with excess zeroes. Current mediation methods addressing this issue are computationally intensive, biased, or challenging to interpret. To overcome these limitations, we propose a new mediation methodology for zero-inflated count outcomes using the marginalized zero-inflated Poisson (MZIP) model and the counterfactual approach to mediation. This novel work gives population-average mediation effects whose variance can be estimated rapidly via delta method. This methodology is extended to cases with exposure-mediator interactions. We apply this novel methodology to explore if diabetes diagnosis can explain BMI differences in healthcare utilization and test model performance via simulations comparing the proposed MZIP method to existing zero-inflated and Poisson methods. We find that our proposed method minimizes bias and computation time compared to alternative approaches while allowing for straight-forward interpretations.

Bayesian modeling of spatially differentiated multivariate enamel defects of the children's primary maxillary central incisor teeth

BACKGROUND

The analysis of dental caries has been a major focus of recent work on modeling dental defect data. While a dental caries focus is of major importance in dental research, the examination of developmental defects which could also contribute at an early stage of dental caries formation, is also of potential interest. This paper proposes a set of methods which address the appearance of different combinations of defects across different tooth regions. In our modeling we assess the linkages between tooth region development and both the type of defect and associations with etiological predictors of the defects which could be influential at different times during the tooth crown development.

METHODS

We develop different hierarchical model formulations under the Bayesian paradigm to assess exposures during primary central incisor (PMCI) tooth development and PMCI defects. We evaluate the Bayesian hierarchical models under various simulation scenarios to compare their performance with both simulated dental defect data and real data from a motivating application.

RESULTS

The proposed model provides inference on identifying a subset of etiological predictors of an individual defect accounting for the correlation between tooth regions and on identifying a subset of etiological predictors for the joint effect of defects. Furthermore, the model provides inference on the correlation between the regions of the teeth as well as between the joint effect of the developmental enamel defects and dental caries. Simulation results show that the proposed model consistently yields steady inferences in identifying etiological biomarkers associated with the outcome of localized developmental enamel defects and dental caries under varying simulation scenarios as deemed by small mean square error (MSE) when comparing the simulation results to real application results.

CONCLUSION

We evaluate the proposed model under varying simulation scenarios to develop a model for multivariate dental defects and dental caries assuming a flexible covariance structure that can handle regional and joint effects. The proposed model shed new light on methods for capturing inclusive predictors in different multivariate joint models under the same covariance structure and provides a natural extension to a nested hierarchical model.

Application of marginalized zero-inflated models when mediators have excess zeroes

Mediation analysis has become increasingly popular over the last decade as researchers are interested in assessing mechanistic pathways for intervention. Although available methods have increased, there are still limited options for mediation analysis with zero-inflated count variables where the distribution of response has a "cluster" of data at the zero value (i.e. distribution of number of cigarettes smoked per day, where nonsmokers cluster at zero cigarettes). The currently available methods do not obtain unbiased population average effects of mediation effects. In this paper, we propose an extension of the counterfactual approach to mediation with direct and indirect effects to scenarios where the mediator is a count variable with excess zeroes by utilizing the Marginalized Zero-Inflated Poisson Model (MZIP) for the mediator model. We derive direct and indirect effects for continuous, binary, and count outcomes, as well as adapt to allow mediator-exposure interactions. Our proposed work allows straightforward calculation of direct and indirect effects for the overall population mean values of the mediator, for scenarios in which researchers are interested in generalizing direct and indirect effects to the population. We apply this novel methodology to an application observing how alcohol consumption may explain sex differences in cholesterol and assess model performance via a simulation study comparing the proposed MZIP mediator framework to existing methods for marginal mediator effects.

Influence of an oral health promotion program on the evolution of dental status in New Caledonia: A focus on health inequities

New Caledonia is a sui generis collectivity of overseas France situated in the south Pacific Ocean. Geographical and social inequalities are superimposed on ethnic disparities with high prevalence of chronic diseases such as oral diseases. In 2012, the health agency has evaluated the children's health status. Then, an oral health promotion program was developed in 2014. Another study was conducted in 2019 in New Caledonia to appreciate the evolution of children's oral health. A sample of 488 9-years-old children was randomly selected. Dental status was clinically recorded, families and children answered questionnaires about oral health determinants. The methodology (sampling, study variables…) was similar to the one used in the 2012 study. Multivariate mixed-models were conducted to compare 2012 and 2019 dental status and to explore the determinants of caries experience in 2019. Results indicated that caries prevalence and experience decreased between 2012 and 2019, with nonetheless various trends depending on the province or type of indexes. The number of carious lesions (d3t + D3T) in 2019 was used as an outcome variable in four models. Model 1 integrated social variables; ethnicity was found to be the only significant determinant. Model 2 was related to oral health care; participation in the program & and access to oral health care was found to be significant. For oral health behaviours (model 3), tooth brushing frequency and consumption of sugary snacks were significant risk factors. In a final model with significant variables from the previous models, ethnicity, accessibility of oral health care, number of sealed molars, consumption of sugary snacks remained explanatory factors. Five years after the implementation of the oral health promotion program, positive changes in oral health have been observed. However, health equity is still an issue with varying health status depending on ethnicity, behavioural factors and accessibility to oral health care.

Evaluation of negative binomial and zero-inflated negative binomial models for the analysis of zero-inflated count data: application to the telemedicine for children with medical complexity trial

BACKGROUND

Two characteristics of commonly used outcomes in medical research are zero inflation and non-negative integers; examples include the number of hospital admissions or emergency department visits, where the majority of patients will have zero counts. Zero-inflated regression models were devised to analyze this type of data. However, the performance of zero-inflated regression models or the properties of data best suited for these analyses have not been thoroughly investigated.

METHODS

We conducted a simulation study to evaluate the performance of two generalized linear models, negative binomial and zero-inflated negative binomial, for analyzing zero-inflated count data. Simulation scenarios assumed a randomized controlled trial design and varied the true underlying distribution, sample size, and rate of zero inflation. We compared the models in terms of bias, mean squared error, and coverage. Additionally, we used logistic regression to determine which data properties are most important for predicting the best-fitting model.

RESULTS

We first found that, regardless of the rate of zero inflation, there was little difference between the conventional negative binomial and its zero-inflated counterpart in terms of bias of the marginal treatment group coefficient. Second, even when the outcome was simulated from a zero-inflated distribution, a negative binomial model was favored above its ZI counterpart in terms of the Akaike Information Criterion. Third, the mean and skewness of the non-zero part of the data were stronger predictors of model preference than the percentage of zero counts. These results were not affected by the sample size, which ranged from 60 to 800.

CONCLUSIONS

We recommend that the rate of zero inflation and overdispersion in the outcome should not be the sole and main justification for choosing zero-inflated regression models. Investigators should also consider other data characteristics when choosing a model for count data. In addition, if the performance of the NB and ZINB regression models is reasonably comparable even with ZI outcomes, we advocate the use of the NB regression model due to its clear and straightforward interpretation of the results.

Twelve Months and Counting: Following Clinical Outcomes in Critical COVID-19 Survivors

Rationale: Recent reports suggest that patients with severe coronavirus disease (COVID-19) often experience long-term consequences of the infection. However, studies on intensive care unit (ICU) survivors are underrepresented. Objectives: We aimed to explore 12-month clinical outcomes after critical COVID-19, describing the longitudinal progress of disabilities, frailty status, frequency of cognitive impairment, and clinical events (rehospitalization, institutionalization, and falls). Methods: We performed a prospective cohort study of survivors of COVID-19 ICU admissions in Sao Paulo, Brazil. We assessed patients every 3 months for 1 year after hospital discharge and obtained information on 15 activities of daily living (basic, instrumental, and mobility activities), frailty, cognition, and clinical events. Results: We included 428 patients (mean age of 64 yr, 61% required invasive mechanical ventilation during ICU stay). The number of disabilities peaked at 3 months compared with the pre-COVID-19 period (mean difference, 2.46; 99% confidence interval, 1.94-2.99) and then decreased at 12 months (mean difference, 0.67; 99% confidence interval, 0.28-1.07). At 12-month follow-up, 12% of patients were frail, but half of them presented frailty only after COVID-19. The prevalence of cognitive symptoms was 17% at 3 months and progressively decreased to 12.1% (P = 0.012 for trend) at the end of 1 year. Clinical events occurred in all assessments. Conclusions: Although a higher burden of disabilities and cognitive symptoms occurred 3 months after hospital discharge of critical COVID-19 survivors, a significant improvement occurred during the 1-year follow-up. However, one-third of the patients remained in worse conditions than their pre-COVID-19 status.

Early Childhood Caries in a Preschool-based Sample in Northeast Italy: Socioeconomic Status and Behavioral Risk Factors

Aim

To assess the relationship among caries and age, gender, immigrant condition, socioeconomic status (SES), and a behavioral risk factor (toothbrushing) in a sample of 3-5-year-old children.

Materials and methods

We performed a random cross-sectional survey from January to December 2017, carrying out clinical examinations to estimate the decayed, missing, and filled teeth (dmft) score. Parents filled in a questionnaire reporting their education level (SES) and the daily frequency of children's toothbrushing. The multivariate analysis assessed the association between caries occurrence and the independent variables. The dmft score was assessed by zero-inflated negative binomial regression (ZINBR).

Results

Out of 1,441 children in the sample, 357 (26.0%) presented at least one caries-affected tooth. Caries risk significantly increased with age and irregular toothbrushing, and it was significantly higher in children with lower SES levels. We modeled caries risk by means of ZINBR. The degree of caries experience increased in children from lower SES positions, immigrant status, and of older age; regular toothbrushing (twice a day) is a predicting factor to belong to the "zero caries" group.

Conclusion

Dental caries represent a significant burden in preschool children and can be regarded as an early marker of social disadvantage.

Clinical significance

The confirmation of the earliest preventive approach as the only chance to grant a "caries free" dentition in all ages and the first target for a pediatric dentist.

How to cite this article

Ferro R, Besostri A, Olivieri A, et al. Early Childhood Caries in a Preschool-based Sample in Northeast Italy: Socioeconomic Status and Behavioral Risk Factors. Int J Clin Pediatr Dent 2022;15(6):717-723.

Alpha globin gene copy number and hypertension risk among Black Americans

BACKGROUND

Alpha globin is expressed in the endothelial cells of human resistance arteries where it binds to endothelial nitric oxide synthase and limits release of the vasodilator nitric oxide. Genomic deletion of the alpha globin gene (HBA) is common among Black Americans and could lead to increased endothelial nitric oxide signaling and reduced risk of hypertension.

METHODS

Community-dwelling US adults aged 45 years or older were enrolled and examined from 2003 to 2007, followed by telephone every 6 months, and reexamined from 2013 to 2016. At both visits, trained personnel performed standardized, in-home blood pressure measurements and pill bottle review. Prevalent hypertension was defined as systolic blood pressure ≥ 140mmHg or diastolic blood pressure ≥ 90mmHg or anti-hypertensive medication use. Droplet digital PCR was used to determine HBA copy number. The associations of HBA copy number with prevalent hypertension, resistant hypertension, and incident hypertension were estimated using multivariable regression.

RESULTS

Among 9,684 Black participants, 7,439 (77%) had hypertension at baseline and 1,044 of those had treatment-resistant hypertension. 1,000 participants were not hypertensive at baseline and participated in a follow up visit; 517 (52%) developed hypertension over median 9.2 years follow-up. Increased HBA copy number was not associated with prevalent hypertension (PR = 1.00; 95%CI 0.98,1.02), resistant hypertension (PR = 0.95; 95%CI 0.86,1.05), or incident hypertension (RR = 0.96; 95%CI 0.86,1.07).

CONCLUSIONS

There were no associations between increased HBA copy number and risk of hypertension. These findings suggest that variation in alpha globin gene copy number does not modify the risk of hypertension among Black American adults.

Does dropout from school matter in taking antenatal care visits among women in Bangladesh? An application of marginalized poisson-poisson mixture model

Background

There exists a lack of research in explaining the link between dropout from school and antenatal care (ANC) visits of women during pregnancy in Bangladesh. The aim of this study is to investigate how the drop out from school influences the ANC visits after controlling the relevant covariates using an appropriate count regression model.

Methods

The association between the explanatory variables and the outcome of interest, ANC visits, have been performed using one-way analysis of variance/independent sample t-test. To examine the adjusted effects of covariates on the marginal mean of count data, Marginalized Poison-Poisson mixture regression model has been fitted.

Results

The estimated incidence rate of antenatal care visits was 10.6% lower for the mothers who were not continued their education after marriage but had at least 10 years of schooling (p-value <0.01) and 20.2% lower for the drop-outed mothers (p-value <0.01) than the mothers who got continued their education after marriage.

Conclusions

To ensure the WHO recommended 8+ ANC visits for the pregnant women of Bangladesh, it is essential to promote maternal education so that at least ten years of schooling should be completed by a woman and dropout from school after marriage should be prevented.

Longer Family Participation in WIC is Associated With Lower Childhood Sugar-Sweetened Beverage Intake

OBJECTIVE

To evaluate if children of families with a longer duration of participation in the Special Supplementation Nutrition Program for Women, Infants, and Children (WIC) consume fewer sugar-sweetened beverages (SSB) and more water.

DESIGN

A repeated cross-sectional study.

SETTING

Conducted among representative samples of WIC-participating families in Los Angeles County, California, in 2014, 2017, and 2020.

PARTICIPANTS

Children aged 4-59 months participating in WIC.

MAIN OUTCOME MEASURES

Daily servings of total SSBs, daily servings of specific types of SSBs, and daily servings of water.

ANALYSIS

Multivariable count regression models were used to estimate incidence rate ratios (IRR) and 95% confidence intervals (CI) for associations of the duration of family WIC participation with daily servings of total SSBs, water, and specific types of SSBs. Zero-inflated negative binomial regression models were used for total SSBs and specific types of SSBs, and Poisson regression was used for water.

RESULTS

Children of families with 2 years of WIC participation consumed significantly fewer daily servings of total SSBs (IRR, 0.95; 95% CI, 0.93-0.98; P = 0.002), fruit-flavored SSBs (IRR, 0.95; 95% CI, 0.91-0.99; P = 0.02), soda (IRR, 0.86; 95% CI, 0.76-0.98; P = 0.02), and water (IRR, 0.99; 95% CI, 0.98 to < 1.00; P = 0.03) than children of families with 1 year of WIC participation. Protective associations for total SSBs, fruit-flavored SSBs, and soda remained statistically significant and increased in magnitude through 10 years of family WIC participation.

CONCLUSIONS AND IMPLICATIONS

Duration of WIC participation was associated with decreased SSB intake by young children. Given the role that increasing water intake in lieu of SSBs plays in child obesity, improving the effectiveness of WIC nutrition education on parental perceptions and provision of fruit-flavored SSBs and water to their children merits detailed evaluation.

Sample size calculation for cluster randomized trials with zero-inflated count outcomes

Cluster randomized trials (CRT) have been widely employed in medical and public health research. Many clinical count outcomes, such as the number of falls in nursing homes, exhibit excessive zero values. In the presence of zero inflation, traditional power analysis methods for count data based on Poisson or negative binomial distribution may be inadequate. In this study, we present a sample size method for CRTs with zero-inflated count outcomes. It is developed based on GEE regression directly modeling the marginal mean of a zero-inflated Poisson outcome, which avoids the challenge of testing two intervention effects under traditional modeling approaches. A closed-form sample size formula is derived which properly accounts for zero inflation, ICCs due to clustering, unbalanced randomization, and variability in cluster size. Robust approaches, including t-distribution-based approximation and Jackknife re-sampling variance estimator, are employed to enhance trial properties under small sample sizes. Extensive simulations are conducted to evaluate the performance of the proposed method. An application example is presented in a real clinical trial setting.

Bayesian spatio-temporal distributed lag modeling for delayed climatic effects on sparse malaria incidence data

Background

In many areas of the Greater Mekong Subregion (GMS), malaria endemic regions have shrunk to patches of predominantly low-transmission. With a regional goal of elimination by 2030, it is important to use appropriate methods to analyze and predict trends in incidence in these remaining transmission foci to inform planning efforts. Climatic variables have been associated with malaria incidence to varying degrees across the globe but the relationship is less clear in the GMS and standard methodologies may not be appropriate to account for the lag between climate and incidence and for locations with low numbers of cases.

Methods

In this study, a methodology was developed to estimate the spatio-temporal lag effect of climatic factors on malaria incidence in Thailand within a Bayesian framework. A simulation was conducted based on ground truth of lagged effect curves representing the delayed relation with sparse malaria cases as seen in our study population. A case study to estimate the delayed effect of environmental variables was used with malaria incidence at a fine geographic scale of sub-districts in a western province of Thailand.

Results

From the simulation study, the model assumptions which accommodated both delayed effects and excessive zeros appeared to have the best overall performance across evaluation metrics and scenarios. The case study demonstrated lagged climatic effect estimation of the proposed modeling with real data. The models appeared to be useful to estimate the shape of association with malaria incidence.

Conclusions

A new method to estimate the spatiotemporal effect of climate on malaria trends in low transmission settings is presented. The developed methodology has potential to improve understanding and estimation of past and future trends in malaria incidence. With further development, this could assist policy makers with decisions on how to more effectively distribute resources and plan strategies for malaria elimination.

Prevalence of Untreated Early Childhood Caries of 5-Year-Old Children in Hong Kong: A Cross-Sectional Study

This cross-sectional survey investigated untreated early childhood caries (ECC) and its associated factors among 5-year-old children in Hong Kong. Children were recruited using a multistage sampling method. One dentist examined the children in kindergarten to diagnose untreated ECC (dt) at the cavitation level. Each child’s demographic information, snacking behaviour, and oral health-related practice were collected using a parental questionnaire. The relationships between the untreated ECC and demographic information, snacking behaviours, and oral health-–related practice were analysed by zero-inflated negative binomial (ZINB) regression analysis. This survey recruited 404 children. Their dt score was 2.8 ± 3.8. The significant untreated ECC (SiUC) index, which was one-third of the children with the highest dt score, was 7.1 ± 3.6. Their untreated ECC prevalence was 57%, which was associated with the district the child lived in. Most children with untreated ECC (71%, 164/231) had never visited a dentist. Children who brushed without toothpaste had more untreated ECC. Children coming from low-income families and with a lower maternal education level had a higher risk of ECC. In conclusion, untreated ECC was prevalent and unevenly distributed among 5-year-old children in Hong Kong. Its prevalence was associated with toothpaste use, family income, maternal education level and the district they lived in.

A Comparative Spatial and Climate Analysis of Human Granulocytic Anaplasmosis and Human Babesiosis in New York State (2013-2018)

Human granulocytic anaplasmosis (HGA) and human babesiosis are tick-borne diseases spread by the blacklegged tick (Ixodes scapularis Say, Acari: Ixodidae) and are the result of infection with Anaplasma phagocytophilum and Babesia microti, respectively. In New York State (NYS), incidence rates of these diseases increased concordantly until around 2013, when rates of HGA began to increase more rapidly than human babesiosis, and the spatial extent of the diseases diverged. Surveillance data of tick-borne pathogens (2007 to 2018) and reported human cases of HGA (n = 4,297) and human babesiosis (n = 2,986) (2013-2018) from the New York State Department of Health (NYSDOH) showed a positive association between the presence/temporal emergence of each pathogen and rates of disease in surrounding areas. Incidence rates of HGA were higher than human babesiosis among White and non-Hispanic/non-Latino individuals, as well as all age and sex groups. Human babesiosis exhibited higher rates among non-White individuals. Climate, weather, and landscape data were used to build a spatially weighted zero-inflated negative binomial (ZINB) model to examine and compare associations between the environment and rates of HGA and human babesiosis. HGA and human babesiosis ZINB models indicated similar associations with forest cover, forest land cover change, and winter minimum temperature; and differing associations with elevation, urban land cover change, and winter precipitation. These results indicate that tick-borne disease ecology varies between pathogens spread by I. scapularis.

Greater inequalities in dental caries treatment than in caries experience: a concentration index decomposition approach

Background

The aim of the current study was to (a) measure the socioeconomic inequalities in oral health and examine whether the inequalities are greater in disease experience or in its treatment and to (b) decompose the factors that influence oral health inequalities among the adults of Guangdong Province.

Methods

A cross-sectional study was conducted among 35- to 44-year-old and 65- to 74-year-old adults in Guangdong Province. All participants underwent oral health examinations and answered questionnaires about their oral health. We measured the concentration indices of the DMFT and its separate components, namely, decayed teeth (DT), missing teeth (MT), and filled teeth (FT), to explore the inequalities in oral health status; then, we analysed its decomposition to interpret the factors that influence the inequalities.

Results

The results showed that significant inequality was concentrated on FT (CI =  0.24, 95% CI = 0.14/0.33, SE = 0.05). The concentration indices for the DMFT (CI =  0.02, 95% CI =  0.02/0.06, SE = 0.02) and MT (CI =  0.02, 95% CI 0.03/0.08, SE = 0.03) were small and close to zero, while the concentration for DT (CI =  − 0.04, 95% CI =  − 0.01/0.02, SE = 0.03) was not statistically significant. The results from the decomposition analysis suggested that a substantial proportion of the inequality was explained by household income, high education level, regular oral examination and type of insurance (5.1%, 12.4%, 43.2%, − 39.6% (Urban Employee Basic Medical Insurance System) and 34.5% (New-Type Rural Medical Collaboration System), respectively).

Conclusions

The results indicated greater inequalities in dental caries than in caries experience. Among the included factors, household income, high education level, and regular oral health examinations had the greatest impact on the inequalities in the number of FT. In addition, the current medical insurance systems, including the Urban Employee Basic Medical Insurance System, Urban Resident Basic Medical Insurance System, and the New-Type Rural Medical Collaboration System, have not been effectively used in oral treatment. Policy-making and the implementation of interventions for tackling socioeconomic oral health inequalities should focus on reducing the burden of treatment and providing greater access to dental care for low-income groups. Welfare policies are skewed towards rural areas and low-income people.

Association Study on Nutrition in the First Year of Life and Molar-Incisor Hypomineralization (MIH)-Results from the GINIplus and LISA Birth Cohort Studies

Molar-incisor hypomineralization (MIH) is a condition with specific clinical presentation whose etiology to date still remains unknown. This study prospectively investigated the association between nutrition during the 1st year of life and the presence of MIH in the permanent dentition. Data from 1070 10-year-old children from two prospective birth cohort studies were included. Information on exclusive breastfeeding (EBF) and introduction of 48 food items into the child’s diet was assessed at 4-, 6-, and 12-month time-points. Food diversity was defined according to the number of food items or food groups introduced into the child’s diet and then subsequent categorization into low-, middle- and high-diversity groups was performed. MIH was scored in the permanent dentition at age of 10 years. The statistical analysis included logistic and Poisson hurdle regression models adjusted for potential confounders. EBF, food item and food group diversity at 4-, 6-, 12-month time-points were found to be non-significant in most of the categories for the development of MIH. However, significantly higher odds for the presence of MIH were found for certain categories. Despite the limitation of this study, such as arbitrary cut-offs for categorization of food items, the results of this study suggest the lack of an association between early nutrition in the first year of life and MIH in the permanent dentition.

Contribution of facility level factors to variation in antibiotic use in long-term care facilities: a national cohort study

OBJECTIVES

To examine national variation in systemic antibiotic use in long-term care facilities (LTCFs) and identify facility characteristics associated with antibiotic utilization.

METHODS

This retrospective cohort study included 312 375 residents of 2536 Australian LTCFs between 2011 and 2016. LTCFs were categorized as low, medium or high antibiotic use facilities according to tertiles of DDDs of systemic antibiotics dispensed per 1000 resident-days. Multivariable logistic regression estimated the associations between facility characteristics (ownership, size, location, medication quality indicator performance, prevalence of after-hours medical practitioner services) and antibiotic use (low versus high).

RESULTS

LTCFs in the lowest and highest antibiotic use categories received a median of 54.3 (IQR 46.5-60.5) and 106.1 (IQR 95.9-122.3) DDDs/1000 resident-days, respectively. Compared with not-for-profit LTCFs in major cities, government-owned non-metropolitan LTCFs were less likely to experience high antibiotic use [adjusted OR (aOR) 0.47, 95% CI 0.24-0.91]. LTCFs with 69-99 residents were less likely to experience high antibiotic use (aOR 0.69, 95% CI 0.49-0.97) than those with 25-47 residents annually. Greater prevalence of medical practitioner services accessed after-hours was associated with high antibiotic use [aOR 1.10 (per 10% increase in after-hours services), 95% CI 1.01-1.21]. South Australian LTCFs (aOR 2.17, 95% CI 1.38-3.39) were more likely, while Queensland (0.43, 95% CI 0.30-0.62) and Western Australian (aOR 0.34, 95% CI 0.21-0.57) LTCFs were less likely to experience high antibiotic use than New South Wales LTCFs.

CONCLUSIONS

Considerable facility level variation in systemic antibiotic use was observed across Australian LTCFs. Identification of facility characteristics associated with antibiotic use provides a basis for targeted stewardship initiatives.

Bayesian variable selection for multivariate zero-inflated models: Application to microbiome count data

Microorganisms play critical roles in human health and disease. They live in diverse communities in which they interact synergistically or antagonistically. Thus for estimating microbial associations with clinical covariates, such as treatment effects, joint (multivariate) statistical models are preferred. Multivariate models allow one to estimate and exploit complex interdependencies among multiple taxa, yielding more powerful tests of exposure or treatment effects than application of taxon-specific univariate analyses. Analysis of microbial count data also requires special attention because data commonly exhibit zero inflation, i.e., more zeros than expected from a standard count distribution. To meet these needs, we developed a Bayesian variable selection model for multivariate count data with excess zeros that incorporates information on the covariance structure of the outcomes (counts for multiple taxa), while estimating associations with the mean levels of these outcomes. Though there has been much work on zero-inflated models for longitudinal data, little attention has been given to high-dimensional multivariate zero-inflated data modeled via a general correlation structure. Through simulation, we compared performance of the proposed method to that of existing univariate approaches, for both the binary ("excess zero") and count parts of the model. When outcomes were correlated the proposed variable selection method maintained type I error while boosting the ability to identify true associations in the binary component of the model. For the count part of the model, in some scenarios the univariate method had higher power than the multivariate approach. This higher power was at a cost of a highly inflated false discovery rate not observed with the proposed multivariate method. We applied the approach to oral microbiome data from the Pediatric HIV/AIDS Cohort Oral Health Study and identified five (of 44) species associated with HIV infection.

Taxes to Unhealthy Food and Beverages and Oral Health in Mexico: An Observational Study

In January 2014, taxes on sugar-sweetened beverages and nonessential energy-dense food were implemented in Mexico to discourage the consumption of these products. Published evaluations have shown reductions in purchases of taxed food and beverages associated with the implementation of this fiscal policy. Although there are some studies on the impact on health based on simulation studies, no evaluations with empirical data on changes in oral health have been published. We used administrative records and data from an epidemiological surveillance system to estimate changes in (1) outpatient visits related to dental caries; (2) having experienced dental caries: Decayed, Missing and Filled Teeth (DMFT) >0 for permanent dentition or dmft >0 for primary dentition (dmft); (3) number of teeth with caries experience (DMFT and dmft), (4) cases with DMFT >0 or dmft >0, and (5) the series of mean DMFT or dmft, associated with the taxes. We estimated probit and negative binomial models for outcomes at individual level, and interrupted time series analysis for population-level outcomes. The implementation of the taxes was associated with negative changes in the trends of outpatient visits, as well as for cases with DMFT >0, dmft >0 and mean DMFT. Taxes were also associated with a lower probability of having experienced dental caries and with a lower number of teeth with caries experience in the samples studied. Our results suggest positive impacts of the implementation of taxes on unhealthy food and beverages in the oral health of Mexicans, which are the first health benefits observed, and add to the health benefits predicted by modeling studies.

TWO-SIGMA: A novel two-component single cell model-based association method for single-cell RNA-seq data

In this paper, we develop TWO-SIGMA, a TWO-component SInGle cell Model-based Association method for differential expression (DE) analyses in single-cell RNA-seq (scRNA-seq) data. The first component models the probability of "drop-out" with a mixed-effects logistic regression model and the second component models the (conditional) mean expression with a mixed-effects negative binomial regression model. TWO-SIGMA is extremely flexible in that it: (i) does not require a log-transformation of the outcome, (ii) allows for overdispersed and zero-inflated counts, (iii) accommodates a correlation structure between cells from the same individual via random effect terms, (iv) can analyze unbalanced designs (in which the number of cells does not need to be identical for all samples), (v) can control for additional sample-level and cell-level covariates including batch effects, (vi) provides interpretable effect size estimates, and (vii) enables general tests of DE beyond two-group comparisons. To our knowledge, TWO-SIGMA is the only method for analyzing scRNA-seq data that can simultaneously accomplish each of these features. Simulations studies show that TWO-SIGMA outperforms alternative regression-based approaches in both type-I error control and power enhancement when the data contains even moderate within-sample correlation. A real data analysis using pancreas islet single-cells exhibits the flexibility of TWO-SIGMA and demonstrates that incorrectly failing to include random effect terms can have dramatic impacts on scientific conclusions. TWO-SIGMA is implemented in the R package twosigma available at https://github.com/edvanburen/twosigma.

Small-area level socio-economic deprivation and tuberculosis rates in England: An ecological analysis of tuberculosis notifications between 2008 and 2012

Background

Tuberculosis (TB) rates in England are among the highest in high-income countries. Poverty and historic and current immigration from high TB incidence parts of the world are two major drivers of tuberculosis in England. However, little has been done in recent years to examine socio-economic trends in TB rates in England, and to disentangle the role of deprivation from that of place of birth in the current TB epidemiology.

Objectives

To assess the association between England’s 2008–2012 TB notification rates and small area-level deprivation, together and separately in the UK-born and foreign-born populations.

Methods

Ecological analysis of the association between quintiles of England’s 2010 Index of Multiple Deprivation (IMD) and TB rates at the Lower-layer Super Output Area (LSOA; average population ~1500) level, using negative binomial and zero-inflated negative binomial regression models, adjusting for age, sex, urban/rural area classification, and area-level percentage of non-White residents.

Results

There was a log-linear gradient between area-deprivation levels and TB rates, with overall TB rates in the most deprived quintile areas three times higher than the least deprived quintile after adjustment for age and sex (IRR = 3.35; 95%CI: 3.16 to 3.55). The association and gradient were stronger in the UK-born than the foreign-born population, with UK-born TB rates in the most deprived quintiles about two-and-a-half times higher than the least deprived quintile (IRR = 2.39; 95%CI: 2.19 to 2.61) after controlling for age, sex, urban/rural classification and percentage of non-White residents; whereas the comparable figure for foreign-born persons was 80% higher (IRR = 1.78; 95%CI: 1.66 to 1.91).

Conclusions

Socio-economic deprivation continues to play a substantial role in sustaining the TB epidemic in England, especially in the UK-born population. This supports the case for further investigations of the underlying social- determinants of TB.

Prenatal smoking and the risk of early childhood caries: A prospective cohort study

Introduction

Dental caries is a chronic complex disease of multifactorial etiology that affects a quarter of U.S. children. This study evaluated the association between prenatal smoking and offspring caries experience and used a negative control exposure analysis to assess if the association is causal.

Methods

Data from 1429 mother-offspring participants of the 1991/92 Avon Longitudinal Study of Parents and Children conducted in Bristol, England were analyzed. Prenatal smoking (yes v. no) and quantity smoked (none, <half pack, ≥half pack) were self-reported while offspring caries experience was determined by clinical oral examinations at 3 time points. Discrete time hazards regression estimated hazard odds of first occurrence of offspring caries, and substituted partner smoking for prenatal smoking in a negative control exposure analysis.

Results

Overall, 22% smoked during pregnancy while 36% of partners smoked. The adjusted hazard odds of first occurrence of caries experience in the offsprings of prenatal smokers compared to the offsprings of non-smokers was 1.42 (95% CI: 1.08, 1.86). Relative to non-smoking, smoking <half pack/day and ≥half pack/day during pregnancy were associated with higher adjusted hazard odds of offspring caries experience: 1.10 (95% CI: 0.79, 1.54) and 1.38 (0.98, 1.95) respectively. Partner smoking was associated with 33% (95% CI: 1.07, 1.65) higher adjusted hazard odds of first offspring caries experience occurrence.

Conclusions

Prenatal and partner smoking appear associated with greater offspring caries experience. The positive association with partner smoking suggests either a shared genetic predisposition or unmeasured common environmental factors with the mother as opposed to a direct biological effect of the intrauterine environment.

Zero inflated count regression for one year prediction of bovine trichomonosis in a compulsory control plan in La Pampa, Argentine

Data from 533 farms with bovine trichomonosis were investigated through hurdle and zero inflated models to quantify the burden of recurrent bovine trichomonosis. The probability of having a positive result in the following year for those farms with a previous positive test was 10.7%. Keeping or buying infected animals increased the odds of having positive results by 2.8 (95% CI = 1.41-5.56). The number first cases significantly decreased the chances of being no-at-risk (OR = 0.64; 95% CI = 0.47-0.89) and the chances of being positive in the following season (OR = 1.09; 95% CI = 1.01-1.18). The number of animals tested significantly increased the chances of being positive in the next season (OR = 1.02; 95% CI = 1.01-1.03). Both the number of positives and the number of animals tested suggest a significant proportion of new cases detected were false positives. These epidemiologic indicators are likely important determinants in the selection of farms requiring more intensive control measures and farms where testing results should be confirmed.

Right-Site Care Programme with a community-based family medicine clinic in Singapore: secondary data analysis of its impact on mortality and healthcare utilisation

OBJECTIVE

Stable patients with chronic conditions could be appropriately cared for at family medicine clinics (FMC) and discharged from hospital specialist outpatient clinics (SOCs). The Right-Site Care Programme with Frontier FMC emphasised care organised around patients in community rather than hospital-based providers, with one identifiable primary provider. This study evaluated impact of this programme on mortality and healthcare utilisation.

DESIGN

A retrospective study without randomisation using secondary data analysis of patients enrolled in the intervention matched 1:1 with unenrolled patients as controls.

SETTING

Programme was supported by the Ministry of Health in Singapore, a city-state nation in Southeast Asia with 5.6 million population.

PARTICIPANTS

Intervention group comprises patients enrolled from January to December 2014 (n=684) and control patients (n=684) with at least one SOC and no FMC attendance during same period.

INTERVENTIONS

Family physician in Frontier FMC managed patients in consultation with relevant specialist physicians or fully managed patients independently. Care teams in SOCs and FMC used a common electronic medical records system to facilitate care coordination and conducted regular multidisciplinary case conferences.

PRIMARY OUTCOME MEASURES

Deidentified linked healthcare administrative data for time period of January 2011 to December 2017 were extracted. Three-year postenrolment mortality rates and utilisation frequencies and charges for SOC, public primary care centres (polyclinic), emergency department attendances and emergency, non-day surgery inpatient and all-cause admissions were compared.

RESULTS

Intervention patients had lower mortality rate (HR=0.37, p<0.01). Among those with potential of postenrolment polyclinic attendance, intervention patients had lower frequencies (incidence rate ratio (IRR)=0.60, p<0.01) and charges (mean ratio (MR)=0.51, p<0.01). Among those with potential of postenrolment SOC attendance, intervention patients had higher frequencies (IRR=2.06, p<0.01) and charges (MR=1.86, p<0.01).

CONCLUSIONS

Intervention patients had better survival, probably because their chronic conditions were better managed with close monitoring, contributing to higher total outpatient attendance frequencies and charges.

Is There an Association between Asthma and Dental Caries and Molar Incisor Hypomineralisation?

This epidemiological study aimed to compare the caries and molar incisor hypomineralisation (MIH) experience in asthmatic and non-asthmatic adolescents assessed at 10 and 15 years of age. 730 adolescents from ongoing birth cohort studies (GINIplus/LISA) from Munich, Germany, were examined for carious lesions at the age of 10 and 15 years to determine caries experience under inclusion of non-cavitated carious lesions D1-2T and the tooth-related decay-missing-filled index. Furthermore, MIH was scored on all permanent teeth according to the criteria of the European Academy of Paediatric Dentistry. The association between caries and MIH prevalence at the 10-year and 15-year follow-up as well as caries incidence with ever having an asthma diagnosis was analysed using hurdle regression models adjusted for potential confounders. Of the 730 adolescents, 52 and 78 were identified as asthmatics at the 10- and 15-year follow-up, respectively. There were no significant differences in caries prevalence or experience between asthma-free participants and any of the asthma groups (taking metered-dose inhaler (MDI) medication vs. taking no MDI medication). However, a significant positive association was found for asthmatic adolescents who did not take MDI medication with higher MIH/T values (OR = 2.56, 95% CI = 1.03-6.37, p = 0.043) compared to non-asthmatics. In conclusion, asthma did not influence the caries status of adolescents in the present study. Interestingly, a significant association was found between adolescents with asthma who did not take MDI medication and the number of MIH-affected teeth. The association between asthma, medication, and MIH needs further confirmation.

Association between poor oral health and diabetes among Indian adult population: potential for integration with NCDs

BACKGROUND

Studies in high-income countries have reported associations between oral health and diabetes. There is however a lack of evidence on this association from low and middle-income countries, especially India. The current study aimed to assess the prevalence of common oral diseases and their association with diabetes.

METHODS

This cross-sectional study was nested within the second Cardiometabolic Risk Reduction in South Asia Surveillance Study. A subset of study participants residing in Delhi were administered the World Health Organization's Oral Health Assessment Questionnaire and underwent oral examination for caries experience and periodontal health assessment using standard indices. Diabetes status was ascertained by fasting blood glucose, glycosylated hemoglobin values or self-reported medication use. Information was captured on co-variates of interest. The association between oral health and diabetes was investigated using Multivariable Zero-Inflated Poisson (ZIP) regression analysis.

RESULTS

Out of 2045 participants, 47% were women and the mean age of study participants was 42.17 (12.8) years. The age-standardised prevalence (95% confidence interval) estimates were 78.9% (75.6-81.7) for dental caries, 35.9% (32.3-39.6) for periodontitis. Nearly 85% participants suffered from at least one oral disease. Compared to diabetes-free counterparts, participants with diabetes had more severe caries experience [Mean Count Ratio (MCR) = 1.07 (1.03-1.12)] and attachment loss [MCR = 1.10 (1.04-1.17)]. Also, the adjusted prevalence of periodontitis was significantly higher among participants with diabetes [42.3%(40.0-45.0)] compared to those without diabetes [31.3%(30.3-32.2)].

CONCLUSION

We found that eight out of ten participants in urban Delhi suffered from some form of oral disease and participants with diabetes had worse oral health. This highlights the need for public health strategies to integrate oral health within the existing Non-Communicable Disease control programs.

Average area under the curve: An alternative method for quantifying the dental caries experience in longitudinal studies

OBJECTIVES

Field-traditional decayed, missing, filled surfaces (dmfs) increments require complete follow-up, only using initial and final visits. Repeated dmfs scores complicate sophisticated statistical models, limiting their utility. Elsewhere, area under the curve (AUC) uses all repeated measures to summarize data. This study applied AUC methodology to caries data, creating average AUCs for dmfs trajectories (dmfs^aAUC ) and comparing increments and dmfs^aAUC values.

METHODS

Longitudinal data were obtained from high-caries risk (i.e. poor, rural, African American community in Perry County, Alabama) infants, 8 to 18 months at baseline. Baseline and five annual visual oral examinations provided dmfs scores. Differences in baseline and final dmfs scores constituted increments. The trapezoidal rule was applied to dmfs trajectories to calculate AUC values which were adjusted for varying follow-up times, producing dmfs^aAUC values. Participants sharing incremental or dmfs^aAUC values had their trajectories and second caries measurements compared. Within-participant increment and dmfs^aAUC differences were evaluated (paired t test, α = 0.05). Comparative analyses required complete follow-up.

RESULTS

The dmfs^aAUC provided forty-eight additional person-years, increasing the potential sample size by 20% (N = 85). Sixty-six children, 5.7 to 6.3 year-olds at study's end, contributed 121 331 person-days to five-year increment and dmfs^aAUC calculations. Trajectories and dmfs^aAUC values varied for participants with equivalent increments; comparable trajectories and different increments resulted from participants with similar dmfs^aAUC values. Within-participant disease amounts were similar.

CONCLUSIONS

When desired, dmfs^aAUC can replace increments as a more data-inclusive summary of longitudinal caries burden, incorporating intermediate visits, incomplete follow-up and time.

Structural equation modelling for associated factors with dental caries among 3-5-year-old children: a cross-sectional study

Background

The aim of the current study was to explore the factors influencing dental caries among 3–5-year-old children in Sichuan Province and the interrelationship between these factors using structural equation modelling (SEM).

Methods

A cross-sectional study was conducted among 2746 3–5-year-old children in Sichuan Province. Examination of caries was conducted on all children and a questionnaire was answered by the children’s caregiver. SEM alternative models were constructed to interpret the intricate relationships between socio-economic status (SES), caregiver’s oral health knowledge, attitudes, children’s oral health behaviours and children’s dental caries.

Result

The results showed that dental caries were significantly associated with dietary behaviours (β = 0.11, SE = 0.03, P = 0.001, BC 95% CI =0.05/0.18) and SES (β = − 0.17, SE = 0.03, P<0.001, BC 95% CI = -0.23/− 0.10) directly, While the indirect effect of SES on dmft is in an opposite direction (β = 0.08, SE = 0.02, BC 95% CI = 0.04/0.12).

Conclusion

We found that unhealthy dietary behaviours increased the prevalence of dental caries. However, oral health knowledge and attitude failed to affect dietary behaviour in this model. This result warns that oral health education should strengthen feeding-related knowledge. Meanwhile, it also reminds that it is easier known than done. Future oral health education should focus on exploring a more effective way for the public to turn knowledge into action.

Overall Effects of Risk Factors Associated with Dental Caries Indices Using the Marginalized Zero-Inflated Negative Binomial Model

The purpose of this paper is to identify risk factors for decayed, missing, and filled permanent teeth (DMFT) in a population of 12-15-year-old schoolchildren and to apply the marginalized zero-inflated negative binomial (MZINB) model for determination and estimation of the overall effects of the risk factors. A cross-sectional survey comprising 764 students aged between 12 and 15 years was used to analyze the association between caries in children and some background characteristics in children and their parents. Information on the samples' social, behavioral, and demographic status was obtained through a series of closed questions. The incidence rate ratios (IRR) were used to associate some risk factors with caries. In the entire sample, the frequency of zero was 194 (25.4%). The result of the shared-parameter marginalized zero-inflated negative binomial (SP-MZINB) model showed that being a girl (IRR = 1.18; p value = 0.021), higher dental visits frequency (IRR = 1.20; p value <0.001), lower tooth brushing frequency (IRR = 0.91; p value = 0.019), higher flossing frequency (IRR = 1.11; p value = 0.001), and lower mothers' education (IRR = 0.89; p value = 0.042) are associated with DMFT. Our results may provide better insights of the factors associated with DMFT, and health programs should focus their efforts on healthcare services, for both preventive and curative purposes. This regression model provides an appropriate fit and meaningful interpretation to handling zero-inflated count outcomes. Also, it provides direct estimates of the effects of risk factors on the overall mean that does not require postmodeling computations.

The associations between lead exposure at multiple sensitive life periods and dental caries risks in permanent teeth

BACKGROUND

Dental caries is an important public health problem in Mexico, a country also faced with high exposure to toxicants including lead (Pb).

METHODS

Participants were 386 children living in Mexico City. Prenatal (trimester 1-3), early-childhood (12, 24, 36, and 48 months of age) and peri-pubertal (10-18 years of age) blood Pb levels were quantified using graphite-furnace atomic-absorption spectroscopy. Maternal patella and tibia bone Pb at 1 month postpartum were quantified with K X-ray fluorescence instrument. Dental caries presence was evaluated using decayed, missing, and filled teeth (DMFT) scores. Peri-pubertal sugar sweetened beverage (SSB) intake was estimated using a 116-item, interview-administered semi-quantitative food frequency questionnaire (FFQ). Total energy adjusted daily SSB intake was generated using the residual approach. Zero inflated negative binomial (ZINB) Poisson regression models were used to examine the associations between Pb with D₁MFT and D₄MFT at adolescence.

RESULTS

Maternal second and third trimester and cumulative early childhood Pb exposure were positively associated with peri-pubertal D₁MFT scores in unadjusted ZINB models (2nd trimester: RR = 1.17 (1.00, 1.37); 3rd trimester: RR = 1.20 (1.03, 1.40); early childhood: RR = 1.22 (1.02, 1.48)). These effect sizes were attenuated and no longer statistically significant after adjusting for covariates. When stratified by high/low SSB intake, a one unit increase of log-transformed 2nd trimester Pb exposure was associated with a 1.41 times (1.06, 1.86) higher D₁MFT count, and 3rd trimester Pb exposure was associated with a 1.50 times (1.18, 1.90) higher D₁MFT count among those with higher than median peri-pubertal SSB. Associations among those with lower SSB intake were roughly half those of the higher group and not statistically significant.

CONCLUSIONS

Pb exposure during sensitive developmental periods was not statistically significantly associated with caries risk after accounting for confounders among our cohort. However, evidence from stratified analysis suggested a Pb-caries association among children with high SSB intake.

Comparison of carotid plaque burden among healthy middle-aged men living in the US, Japan, and South Korea

BACKGROUND

Carotid plaque has emerged as a marker of coronary heart disease (CHD) risk. Comparison of carotid plaque burden between different race/ethnic groups may provide a relative estimate of their future CHD risk.

METHODS

We conducted a population-based study among apparently healthy middle-aged men aged 40-49 years (ERA JUMP study (n = 924)) and recruited 310 Whites in Pittsburgh, US, 313 Japanese in Otsu, Japan, and 301 Koreans in Ansan, South Korea. The number of carotid plaque and CHD risk factors was assessed using a standardized protocol across all centers. The burden of carotid plaque was compared between race/ethnic groups after adjustment for age and BMI, and after multivariable adjustment for other CHD risk factors using marginalized zero-inflated Poisson regression models. Cross-sectional associations of risk factors with plaque were examined.

RESULTS

Whites (22.8%) had more than four-fold higher prevalence (p < 0.01) of carotid plaque than Japanese men (4.8%) while the prevalence among Koreans was 10.6%. These differences remained significant after adjustment for age, BMI as well as other risk factors - incidence density ratio (95% confidence interval) for plaque was 0.13 (0.07, 0.24) for Japanese and 0.32 (0.18, 0.58) for Koreans as compared to Whites. Age, hypertension and diabetes were the only risk factors significantly associated with presence of carotid plaque in the overall population.

CONCLUSION

Whites have significantly higher carotid plaque burden than men in Japan and Korea. Lower carotid plaque burden among Japanese and Koreans is independent of traditional CVD risk factors.

CLINICAL AND LABORATORY SUBSTANTIATION OF APPLICATION OF TREATMENT-AND-PROPHYLACTIC GEL REDUCING TOOTHPASTE WITH SODIUM FLUORIDE IN YOUNG PATIENTS

Object. The paper analyzes the change in the physical and chemical properties of mixed saliva in patients with the course of use of toothpaste "Sensodyne® Recovery and protection" containing NovaMin and sodium fluoride. The analysis of the survey of organoleptic properties of toothpaste, clinical examination of patients with hyperesthesia and laboratory parameters of mixed saliva in dynamics was carried out. Purpose. Rationale for the use of therapeutic and prophylactic toothpaste "Sensodyne® Recovery and protection" with sodium fluoride for sensitive teeth in young patients. Methodology. A clinical examination of the oral cavity of young patients (50 men, mean age of 22.50±2.59 years), index estimation of a condition of the teeth (CPUs, municipal production unitary enterprise), oral hygiene (J. R. Green, J. R. Vermillion, 1964), the determination of "teeth sensitivity" (method L. Y. Nut–Litovskogo S. B.); the study of mixed saliva (qualitative analysis, salumeria; concentration of fluorine ions and sodium, pH, redox potential, total zhestkost) exchange rate before and after application of toothpaste. Results. A pronounced clinical effect was obtained, which manifests itself in the cleansing qualities (p≤0.05), and in the elimination of hyperesthesia (p≤0.05) in all patients. The increase of pH values (p≤0.05) was revealed. After cleaning in the sample of mixed saliva, the concentration of fluoride ions increases by 22%, the content of sodium ions decreases by 35.4%, the content of calcium and magnesium ions decreases. This contributes to the formation of stable fluorapatite Ca5(PO4)3F in the surface layers of enamel. calcium ions from phosphosilicate calcium-sodium (NovaMin) go directly from the toothpaste "Sensodyne® repair and protect" with the sodium fluoride in the construction of the hydroxyapatite of tooth enamel. Summary. Thus, the analysis of the results of the survey evaluation of the organoleptic properties of toothpaste "Sensodyne® Recovery and protection" containing sodium fluoride, which are estimated to be highly valued, clinical examination of patients with hyperesthesia and laboratory parameters of mixed saliva in dynamics, showed a significant clinical effect: improving the cleaning ability of toothpaste, reducing the sensitivity of teeth in 100% of patients.

Models for analyzing zero-inflated and overdispersed count data: an application to cigarette and marijuana use

INTRODUCTION

This paper describes different methods for analyzing counts and illustrates their use on cigarette and marijuana smoking data.

METHODS

The Poisson, zero-inflated Poisson (ZIP), hurdle Poisson (HUP), negative binomial (NB), zero-inflated negative binomial (ZINB) and hurdle negative binomial (HUNB) regression models are considered. The different approaches are evaluated in terms of the ability to take into account zero-inflation (extra zeroes) and overdispersion (variance larger than expected) in count outcomes, with emphasis placed on model fit, interpretation, and choosing an appropriate model given the nature of the data. The illustrative data example focuses on cigarette and marijuana smoking reports from a study on smoking habits among youth e-cigarette users with gender, age, and e-cigarette use included as predictors.

RESULTS

Of the 69 subjects available for analysis, 36% and 64% reported smoking no cigarettes and no marijuana, respectively, suggesting both outcomes might be zero-inflated. Both outcomes were also overdispersed with large positive skew. The ZINB and HUNB models fit the cigarette counts best. According to goodness-of-fit statistics, the NB, HUNB, and ZINB models fit the marijuana data well, but the ZINB provided better interpretation.

CONCLUSION

In the absence of zero-inflation, the NB model fits smoking data well, which is typically overdispersed. In the presence of zero-inflation, the ZINB or HUNB model is recommended to account for additional heterogeneity. In addition to model fit and interpretability, choosing between a zero-inflated or hurdle model should ultimately depend on the assumptions regarding the zeros, study design, and the research question being asked.

IMPLICATIONS

Count outcomes are frequent in tobacco research and often have many zeros and exhibit large variance and skew. Analyzing such data based on methods requiring a normally distributed outcome are inappropriate and will likely produce spurious results. This study compares and contrasts appropriate methods for analyzing count data, specifically those with an over-abundance of zeros, and illustrates their use on cigarette and marijuana smoking data. Recommendations are provided.

Chronic Condition Combinations and Productivity Loss Among Employed Nonelderly Adults (18 to 64 Years)

OBJECTIVE

We examined the relationship between specific chronic condition combinations and productivity loss measured by missed work days among nonelderly employed adults with at least two physical chronic conditions of arthritis, diabetes mellitus, heart disease, and hypertension.

METHODS

We analyzed data from the Medical Expenditure Panel Survey for the years 2004 to 2012.

RESULTS

Adults with arthritis/diabetes/heart disease had the highest average missed work days (14.42). In the adjusted model, compared with adults with arthritis/hypertension, adults with diabetes/heart disease and arthritis/heart disease/hypertension had significantly higher missed work days, while adults with diabetes/hypertension had significantly lower missed work days.

CONCLUSION

Specific chronic condition combinations have a high burden of disease in terms of productivity loss. Workplace health programs that address multiple health conditions at the same time should be implemented to reduce missed work days.

Interpreting Poisson Regression Models in Dental Caries Studies

Oral epidemiology involves studying and investigating the distribution and determinants of dental-related diseases in a specified population group to inform decisions in the management of health problems. In oral epidemiology studies, the hypothesis is typically followed by a cogent study design and data collection. Appropriate statistical analysis is essential to demonstrate the scientific association between the independent factors and the target variable. Analysis also helps to develop and build a statistical model. Poisson regression and its extensions have gained more attention in caries epidemiology than other working models such as logistic regression. This review discusses the fundamental principles and basic knowledge of Poisson regression models. It also introduces the use of a robust variance estimator with a focus on the "robust" interpretation of the model. In addition, extensions of regression models, including the zero-inflated model, hurdle model, and negative binomial model, and their interpretation in caries studies are reviewed. Principles of model fitting, including goodness-of-fit measures, are also discussed. Clinicians and researchers should pay attention to the statistical context of the models used and interpret the models to improve the oral and general health of the communities in which they live.

Dental caries experience and determinants in young adults of the Northern State Medical University, Arkhangelsk, North-West Russia: a cross-sectional study

Background

Little information exists about the experience of and risk factors for dental caries in young adults in Russia. We investigated dental caries experience and determinants in medical and dental students in North-West Russia.

Methods

This cross-sectional study included 442 medical and 309 dental undergraduate students of Russian nationality aged 18–25 years from the Northern State Medical University, Arkhangelsk, Russia. Information on socio-demographic factors and oral health behaviour (regularity of dental visits, frequency of tooth-brushing, using toothpaste with fluoride, and skipping tooth-brushing) was obtained from a structured, self-administered questionnaire. Dental caries experience was based on the decayed (D) missing (M) filled (F) teeth (T) index and the Significant Caries (SiC) index, which were assessed through dental examination. Students with a DMFT index ≥9 were placed in the SiC group. Negative binomial hurdle and multivariable binary logistic regressions were used for statistical analyses.

Results

The prevalence of dental caries (DMFT >0) was 96.0%, overall mean DMFT index was 7.58 (DT: 0.61, MT: 0.12, and FT: 6.84), and the corresponding SiC index was 12.50. Age 21–25 years (incidence rate ratio [IRR] = 1.09, 95% confidence interval [CI]: 1.01–1.18), being a female (IRR = 1.10, 95% CI: 1.01–1.20), high subjective socioeconomic status (SES) [IRR = 1.11, 95% CI: 1.02–1.21], and skipping tooth-brushing (IRR = 1.09, 95% CI: 1.00–1.19) were associated with a higher DMFT index. DMFT index also increased among students who reported regular dental visits (IRR = 1.22, 95% CI: 1.10–1.36), but their odds of being in the dental caries-free group decreased (odds ratio [OR] = 0.38, 95% CI: 0.18–0.82). Significant predictors of being categorised to the SiC group were older age (OR = 1.41, 95% CI: 1.03–1.92), high subjective SES (OR = 1.57, 95% CI: 1.13–2.19), and regular dental visits (OR = 2.34, 95% CI: 1.56–3.51).

Conclusions

A high prevalence of dental caries and high DMFT index, with a dominance of FT, were observed in our Russian medical and dental students. Age, sex, subjective SES, regular dental visits, and skipping tooth-brushing were determinants of dental caries experience.

Dental caries status and its associated factors among 5-year-old Hong Kong children: a cross-sectional study

BACKGROUND

This study investigated dental caries status and its associated factors among 5-year-old children in Hong Kong.

METHOD

This cross-sectional survey was conducted in 2016. It comprised a questionnaire survey and a clinical examination. Kindergarten children aged 5 were recruited using a multistage sampling method. Parents of the participating children were asked about their children's demographic information, sugary snacking behaviours, and oral health-related behaviours and about their own oral health knowledge. One trained dentist performed oral examinations on the children. Caries experience was measured using the dmft index. The relationships between the dmft scores and background information, sugary snacking behaviours, oral health-related behaviours and parental dental knowledge were studied using a zero-inflated negative binomial (ZINB) regression analysis.

RESULTS

A total of 570 children were invited to participate, and 501 completed the oral examination (response rate: 88%). The prevalence of dental caries was 55%, and the mean dmft score was 2.7 ± 3.7. Decayed teeth (dt) constituted 93% of caries experience. ZINB analysis found that children who visited a dentist, who were taken care of primarily by grandparents and whose parental dental knowledge levels were moderate had higher dmft scores. Children who ate sugary snacks more than twice daily, had irregular dental attendance and lived in low-income families had a significantly higher chance of having dental caries.

CONCLUSIONS

Dental caries was prevalent among 5-year-old Hong Kong children, and most of the decayed teeth were untreated. The caries prevalence of the children was related to their frequency of sugary snack intake, dental attendance and socio-economic background.

Oxalobacter formigenes-associated host features and microbial community structures examined using the American Gut Project

BACKGROUND

Increasing evidence shows the importance of the commensal microbe Oxalobacter formigenes in regulating host oxalate homeostasis, with effects against calcium oxalate kidney stone formation, and other oxalate-associated pathological conditions. However, limited understanding of O. formigenes in humans poses difficulties for designing targeted experiments to assess its definitive effects and sustainable interventions in clinical settings. We exploited the large-scale dataset from the American Gut Project (AGP) to study O. formigenes colonization in the human gastrointestinal (GI) tract and to explore O. formigenes-associated ecology and the underlying host-microbe relationships.

RESULTS

In >8000 AGP samples, we detected two dominant, co-colonizing O. formigenes operational taxonomic units (OTUs) in fecal specimens. Multivariate analysis suggested that O. formigenes abundance was associated with particular host demographic and clinical features, including age, sex, race, geographical location, BMI, and antibiotic history. Furthermore, we found that O. formigenes presence was an indicator of altered host gut microbiota structure, including higher community diversity, global network connectivity, and stronger resilience to simulated disturbances.

CONCLUSIONS

Through this study, we identified O. formigenes colonizing patterns in the human GI tract, potential underlying host-microbe relationships, and associated microbial community structures. These insights suggest hypotheses to be tested in future experiments. Additionally, we proposed a systematic framework to study any bacterial taxa of interest to computational biologists, using large-scale public data to yield novel biological insights.