James Beck - Profile on Academia.edu (original) (raw)

Papers by James Beck

Statistical Modelling, Sep 23, 2014

We develop robust methods for analyzing clustered data where estimation of marginal regression pa... more We develop robust methods for analyzing clustered data where estimation of marginal regression parameters is of interest. Inverse cluster size reweighting in the objective function to be minimized is incorporated to handle the issue of informative cluster size. Performance of the resulting estimators is studied by simulation. Large sample inference and variance estimation is carried out. The methodology is illustrated using a periodontal disease dataset.

Carolina Digital Repository (University of North Carolina at Chapel Hill), 2016

Ignorance of the mechanisms responsible for the availability of information presents an unusual p... more Ignorance of the mechanisms responsible for the availability of information presents an unusual problem for analysts. It is often the case that the availability of information is dependent on the outcome. In the analysis of cluster data we say that a condition for informative cluster size (ICS) exists when the inference drawn from analysis of hypothetical balanced data varies from that of inference drawn on observed data. Much work has been done in order to address the analysis of clustered data with informative cluster size; examples include Inverse Probability Weighting (IPW), Cluster Weighted Generalized Estimating Equations (CWGEE), and Doubly Weighted Generalized Estimating Equations (DWGEE). When cluster size changes with time, i.e., the data set possess temporally varying cluster sizes (TVCS), these methods may produce biased inference for the underlying marginal distribution of interest. We propose a new marginalization that may be appropriate for addressing clustered longitudinal data with TVCS. The principal motivation for our present work is to analyze the periodontal data collected by Beck et al. (1997, Journal of Periodontal Research 6, 497-505). Longitudinal periodontal data often exhibits both ICS and TVCS as the number of teeth possessed by participants at the onset of study is not constant and teeth as well as individuals may be displaced throughout the study.

Carolina Digital Repository (University of North Carolina at Chapel Hill), 2009

Purpose-Assess the association between the visible presence of 3 rd molars and the severity of pe... more Purpose-Assess the association between the visible presence of 3 rd molars and the severity of periodontal pathology on teeth more anterior in the mouth. Subjects and Methods-This analysis included dentate participants 52 to 74 years old from the Dental Atherosclerosis Risk in Communities (DARIC) Study who underwent an oral examination which included periodontal probing depths (PD) on all visible teeth including 3 rd molars. PD ≥4mm and clinical attachment level (CAL) ≥3mm were indicator variables for periodontal pathology. Explanatory variables were the presence or absence of visible 3 rd molars. Covariates included: gender, ethnicity, age, income level, education, and smoking status. Outcome variables for periodontal pathology were: mean PD, the extent (% probing sites) PD≥4mm, and the extent (% probing sites) CAL>3mm. Outcomes between subjects with visible 3 rd molars and no visible 3 rd molars were compared by descriptive statistics and Chi-square tests with significance set at 0.05. Multivariable modeling was performed using SAS Proc GLM to calculate least squared means adjusting for study outcome variables and covariates.

Journal of Periodontology, Feb 1, 2017

Background-Our goal was to develop data analytical tools that enable the identification and defin... more Background-Our goal was to develop data analytical tools that enable the identification and definition of distinct periodontal profile and tooth profile classes (PPC/TPC) of individuals using detailed clinical measures at the tooth-level, including both periodontal measurements and tooth loss. Materials and Methods-Full-mouth clinical periodontal measurements (7 indices) from 6,793 subjects from the Dental Atherosclerosis Risk in Communities Study (DARIC) were used to identify PPC. A custom Latent Class Analysis (LCA) procedure was developed to identify seven distinct PPC/TPC. Each PPC/TPC was associated with different clinical phenotypes. The NHANES (2009-2010/2011-2012) and the Piedmont study populations were used for validation with total of 7,785 subjects. Results-LCA method identified members of seven distinct periodontal profile classes (PPC A-G) and seven distinct tooth profile classes (TPC A-G) ranging from health to severe periodontal disease status. The method enabled the identification of classes with common clinical manifestations that are hidden under the current periodontal classification schemas. Class

Carolina Digital Repository (University of North Carolina at Chapel Hill), 2008

Objective-Characterization of serum C-Reactive Protein (CRP) levels in a diverse population of he... more Objective-Characterization of serum C-Reactive Protein (CRP) levels in a diverse population of healthy pregnant women using a high sensitivity assay. Study Design-Cross-sectional analysis of a cohort of 775 pregnant women. CRP measured on serum specimens drawn <26 weeks gestation using highly sensitive ELISA kits. Results-Median CRP was 4.8 mg/L (inter-quartile range 0.63 -15.7). Black women had higher median CRP values than whites (7.68 mg/L vs 2.59 mg/L, p<.001). Black women demonstrated higher levels of CRP even after controlling for known confounding factors such as smoking and maternal weight. is an inflammatory stressor. The etiology of racial differences is unclear, but may be important for understanding racial disparities in the incidence inflammatory disorders such as preterm labor and pre-eclampsia.

Community Dentistry and Oral Epidemiology, Mar 7, 2013

Objectives: This study charted the trajectories of dental caries, including decayed teeth, missin... more Objectives: This study charted the trajectories of dental caries, including decayed teeth, missing teeth and filled teeth among older Americans over a 5-year period. In particular, it focused on racial differences in the levels of and rates of change in dental caries experience. Methods: Data came from the Piedmont Dental Study. The sample included 810 older Americans who were dentate at the baseline with up to 4 repeated observations between 1988 and 1994. Hierarchical linear models were employed in depicting intrapersonal and interpersonal differences in dental caries experience. Results: Different measures of caries outcomes exhibited distinct trajectories. On average, the number of decayed teeth decreased over time, whereas missing teeth increased. In contrast, the number of filled teeth remained stable during a 5-year period. Relative to their white counterparts, older black Americans had more decayed teeth and missing teeth but fewer filled teeth. Blacks and whites differed in the levels of dental caries but not in their rates of change except for missing teeth. Even when demographic and socioeconomic attributes were adjusted, racial variations in dental caries experience remained significant. Conclusions: Although significantly correlated, various dental caries outcomes move along different paths over time. In view of the persistent racial disparities in dental caries trajectories, future interventions to minimize such variations among older Americans in the levels of and the rates of change in dental caries experience are clearly warranted.

Journal of Periodontology, Feb 1, 2010

We thank Ms. Pickett for her interest in ''The American Journal of Cardiology and Journal of Peri... more We thank Ms. Pickett for her interest in ''The American Journal of Cardiology and Journal of Periodontology Editors' Consensus: Periodontitis and Atherosclerotic Cardiovascular Disease'' and her thoughtful comments, and we appreciate the opportunity to clarify some of the confusion regarding the aim of the document and the evidence. The consensus report attempted to translate what is currently known about the relationship between these two diseases into practical application, while recognizing that recommendations are based on judgments of potential risks and benefits given the current state of knowledge. Ms. Pickett concludes that there is no evidence that atherosclerotic events can be prevented with periodontal therapy, and therefore suggests that the recommendations cannot be supported. We concur with Ms. Pickett that there is no current direct evidence that atherosclerotic cardiovascular disease (CVD) events can be prevented by treating periodontal disease, and we repeatedly indicated the same in the document. To emphasize this point, we placed the following statement immediately before the recommendations: ''Although the treatment of periodontitis reduces systemic markers of inflammation and endothelial dysfunction, no prospective periodontitis intervention studies have evaluated CVD outcomes.'' Thus, we tried to make clear in the recommendations that clinicians should not be treating periodontal disease solely for the purpose of preventing CVD events. However, there is growing evidence that periodontal therapy can reduce traditional risk factors for cardiovascular events, for example, elevated C-reactive protein and impaired endothelial function. Clinicians are very interested in what these studies mean and how they should apply the information. Ms. Pickett also suggests that an added risk of 24% to 35% reported in one systematic review and relative risk ratios between 1.1 and 2.2 are very weak to moderate associations. While this is true, periodontal disease and heart disease are very prevalent in the population, and an effect size that is weak to moderate can affect a large number of lives. For example, in 2005, there were 864,000 deaths from cardiovascular diseases in the United States, according to the American Heart Association. 1 These events occurred in an at-risk adult population, over age 18, of 296 million individuals (2005 U.S. census data 2 ). A 25% increase in risk (i.e., a 1.25 odds ratio) would translate into roughly 216,000 new lethal events for that

Dental Caries a Risk Factor for Intracerebral Hemorrhage

Cerebrovascular Diseases

Introduction: Streptococcus mutans is a known cause of dental caries that contains a collagen-bin... more Introduction: Streptococcus mutans is a known cause of dental caries that contains a collagen-binding protein, Cnm, and exhibits inhibition of platelet aggregation and matrix metalloproteinase-9 activation. This strain has been linked to aggravation of experimental intracerebral hemorrhage (ICH) and may be a risk factor for ICH. The purpose of this study was to test the association between dental caries and incident ICH. Methods: The presence of dental caries and periodontal disease was assessed in subjects from the Dental Atherosclerosis Risk in Communities (DARIC) study without prior stroke or ICH. This cohort was followed for incident ICH over a period of 10 years. Cox regression was used to compute crude and adjusted hazards ratio from the dental assessment. Results: Among 6,315 subjects, dental surface caries and/or root caries were recorded in 1,338 (27%) subjects. Of those, 7 (0.5%) had incident ICH over a period of 10 years following the visit 4 assessment. Of the remaining ...

JNCI Cancer Spectrum

Background Oral health is a key indicator of overall health, well-being, and quality of life. Sev... more Background Oral health is a key indicator of overall health, well-being, and quality of life. Several studies have provided new evidence about the role of oral diseases, specifically periodontitis, in generating risk for various forms of cancers, including lung, colorectal, and pancreatic cancers. Methods Incident lung cancer cases (n = 192) and matched controls (n = 192) were selected from participants of the CLUE I and CLUE II cohorts. Archived serum samples collected from participants in 1974 (in CLUE I) were analyzed using immunoblotting for immunoglobulin G (IgG) antibody levels to 13 bacteria of the periodontium. Associations between antibody levels and lung cancer were estimated using conditional logistic regression. Results Most of the periodontal bacterial antibodies measured were inversely associated with lung cancer risk; of these, 3 were statistically significant (Prevotellaintermedia, Actinomyces naeslundii, and Veillonella parvula). A statistically significant positive...

Supplementary Method 1, Tables S1-S8, and Figures S1-S2 from Periodontal and Other Oral Bacteria ... more Supplementary Method 1, Tables S1-S8, and Figures S1-S2 from Periodontal and Other Oral Bacteria and Risk of Lung Cancer in the Atherosclerosis Risk in Communities (ARIC) Study

JAMA Network Open

ImportanceChlorhexidine mouthwash enhances treatment effects of conventional periodontal treatmen... more ImportanceChlorhexidine mouthwash enhances treatment effects of conventional periodontal treatment, but data on chlorhexidine as a source of heterogeneity in meta-analyses assessing the treatment of maternal periodontitis in association with birth outcomes are lacking.ObjectiveTo assess possible heterogeneity by chlorhexidine use in randomized clinical trials (RCTs) evaluating the effect of periodontal treatment (ie, scaling and root planing [SRP]) vs no treatment on birth outcomes.Data SourcesCochrane Oral Health’s Trials Register, Cochrane Pregnancy and Childbirth’s Trials Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE Ovid, Embase Ovid, LILACS BIREME Virtual Health Library (Latin American and Caribbean Health Science Information database), US National Institutes of Health Ongoing Trials Register (ClinicalTrials.gov), and the WHO International Clinical Trials Registry Platform were searched through March 2022.Study SelectionRCTs were included if they w...

Observational studies indicate that periodontal disease may increase the risk of colorectal, lung... more Observational studies indicate that periodontal disease may increase the risk of colorectal, lung, and pancreatic cancers. We tested these associations using two-sample Mendelian randomization to emulate a randomized study with observational data. We developed an instrument including single nucleotide polymorphisms with strong genome-wide association study evidence for associations with aggressive and/or advanced periodontal disease. We used this instrument to assess associations with summary-level genetic data for colorectal cancer (n=58,131 cases), lung cancer (n=18,082 cases), and pancreatic cancer (n=9254 cases). The genetic predisposition index for periodontitis was significantly associated with an increased risk of colorectal cancer (p=0.026), colon cancer (p=0.021), proximal colon cancer (p=0.013), and colorectal cancer among females (p=0.039); however, it was not significantly associated with the risk of lung cancer or pancreatic cancer, overall or within most subgroups. Fur...

Statistical modelling, 2014

Maternal Periodontitis and Prematurity. Part I: Obstetric Outcome of Prematurity and Growth Restriction

Annals of Periodontology, 2001

Oral Conditions and Pregnancy (OCAP) is a 5‐year prospective study of pregnant women designed to ... more Oral Conditions and Pregnancy (OCAP) is a 5‐year prospective study of pregnant women designed to determine whether maternal periodontal disease contributes to the risk for prematurity and growth restriction in the presence of traditional obstetric risk factors. Full‐mouth periodontal examinations were conducted at enrollment (prior to 26 weeks gestational age) and again within 48 hours postpartum to assess changes in periodontal status during pregnancy. Maternal periodontal disease status at antepartum, using a 3‐level disease classification (health, mild, moderate‐severe) as well as incident periodontal disease progression during pregnancy were used as measures of exposures for examining associations with the pregnancy outcomes of preterm birth by gestational age (GA) and birth weight (BW) adjusting for race, age, food stamp eligibility, marital status, previous preterm births, first birth, chorioamnionitis, bacterial vaginosis, and smoking. Interim data from the first 814 deliveri...

Stroke, 2007

Background and Purpose— Leukocyte count is an independent predictor of stroke. We investigated th... more Background and Purpose— Leukocyte count is an independent predictor of stroke. We investigated the association between leukocyte count and progression of aortic atheroma over 12 months in stroke/transient ischemic attack (TIA) patients. Methods— Consecutive ischemic stroke and transient ischemic attack patients underwent 12-month sequential transesophageal echocardiography and were assessed for total and differential leukocyte counts on admission. Paired aortic plaque images were assessed for several parameters, including changes in grade, intimal-medial thickness (IMT), and cross-sectional area. Multivariate linear and logistic regressions were used to calculate the effect of leukocyte count on the change in aortic atheromas over 12 months. Results— Of the 115 participants (mean±SD age, 64.6±11.9 years; 53.1% men; 73.4% white, 24.2% black, and 2.3% Asian), 45 (35%) showed clinically significant progression of aortic atheromas (maximal change in IMT >0.70 mm over 12 months). The ...

Obstetrics & Gynecology, 2006

The goal was to estimate whether maternal periodontal disease was predictive of preterm (less tha... more The goal was to estimate whether maternal periodontal disease was predictive of preterm (less than 37 weeks) or very preterm (less than 32 weeks) births. A prospective study of obstetric outcomes, entitled Oral Conditions and Pregnancy (OCAP), was conducted with 1,020 pregnant women who received both an antepartum and postpartum periodontal examination. Predictive models were developed to estimate whether maternal exposure to either periodontal disease at enrollment (less than 26 weeks) and/or periodontal disease progression during pregnancy, as determined by comparing postpartum with antepartum status, were predictive of preterm or very preterm births, adjusting for risk factors including previous preterm delivery, race, smoking, social domain variables, and other infections. Incidence of preterm birth was 11.2% among periodontally healthy women, compared with 28.6% in women with moderate-severe periodontal disease (adjusted risk ratio [RR] 1.6, 95% confidence interval [CI] 1.1-2.3). Antepartum moderate-severe periodontal disease was associated with an increased incidence of spontaneous preterm births (15.2% versus 24.9%, adjusted RR 2.0, 95% CI 1.2-3.2). Similarly, the unadjusted rate of very preterm delivery was 6.4% among women with periodontal disease progression, significantly higher than the 1.8% rate among women without disease progression (adjusted RR 2.4, 95% CI 1.1-5.2). The OCAP study demonstrates that maternal periodontal disease increases relative risk for preterm or spontaneous preterm births. Furthermore, periodontal disease progression during pregnancy was a predictor of the more severe adverse pregnancy outcome of very preterm birth, independently of traditional obstetric, periodontal, and social domain risk factors.

Journal of Periodontal Research, 1997

The purpose of this meta‐analysis was to provide a quantitative overview of clinical trials asses... more The purpose of this meta‐analysis was to provide a quantitative overview of clinical trials assessing the use of systemic metronidazole (S‐MET) as an adjunct to scaling and root planing (S&RP) in the treatment of adult periodontitis. Eight clinical trials were chosen based upon a priori selection criteria, and two outcomes, “reduction in probing pocket depth” (PD) and “gain in clinical attachment level” (CAL), were analyzed. Results for each outcome were stratified by initial PD 1–3 mm, 4–6 mm, or ≥7 mm and length of follow‐up 4–6 wk, 9–13 wk, or 14–26 wk. S‐MET in conjunction with S&RP was superior to S&RP alone in reducing PD where initial PD was 4–6 mm and follow‐up was 9–13 wk (0.43 mm; 99% CI 0.12, 0.73). No significant advantage was observed for S‐MET for reducing PD where initial PD was less than 4 mm or follow‐up was longer than 13 wk. S‐MET in conjunction with S&RP was superior to S&RP alone in reducing CAL where initial PD was 4–6 mm and follow‐up was 4–6 wk (0.29; 99% CI ...

The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 2013

Background. The complex physiological, psychological, and functional changes at the end of life m... more Background. The complex physiological, psychological, and functional changes at the end of life may dramatically affect oral health. However, evidence regarding oral health changes at the end of life is scarce. This study's objective was to examine self-rated oral health and oral health behaviors among community-dwelling elders in the last year of life. Methods. This study was a retrospective longitudinal study including 810 dentate community-dwelling older adults aged 65 and older. Based on death certificate data, the participants were retrospectively classified into two groups: died within 1 year after the last interview (end-of-life group) and survived more than 1 year after the last interview (comparison group). Participants were interviewed at baseline, 18, 36, 60, and 84 months regarding their sociodemographics, self-reported oral health, oral conditions, use of oral health services, and preventive behaviors. Generalized estimating equations were used to compare self-reported oral health and oral health behaviors between two groups. Results. After adjusting for sociodemographics, the end-of-life group was more likely to rate their oral health (odds ratio [OR] = 2.94, 95% confidence interval [CI]: 1.32, 6.54) and overall health (OR = 2.35, 95% CI: 1.12, 4.91) as bad than the comparison group. End-of-life participants were also more likely to dislike their mouth appearance (OR = 2.27, 95% CI: 1.07, 4.83) and rate their ability to taste (OR = 7.24, 95% CI: 2.64, 19.77) and smell (OR = 2.98, 95% CI: 1.09, 8.15) as bad. There was no difference in self-reported oral conditions, use of oral health services, and preventive behaviors. Self-rated oral health significantly declines in the last year of life.

Journal of Dental Research, 2007

Maternal oral infection, caused by bacteria such as C. rectus or P. gingivalis, has been implicat... more Maternal oral infection, caused by bacteria such as C. rectus or P. gingivalis, has been implicated as a potential source of placental and fetal infection and inflammatory challenge, which increases the relative risk for pre-term delivery and growth restriction. Intra-uterine growth restriction has also been reported in various animal models infected with oral organisms. Analyzing placental tissues of infected growth-restricted mice, we found down-regulation of the imprinted Igf2 gene. Epigenetic modification of imprinted genes via changes in DNA methylation plays a critical role in fetal growth and development programming. Here, we assessed whether C. rectus infection mediates changes in the murine placenta Igf2 methylation patterns. We found that infection induced hypermethylation in the promoter region-P0 of the Igf2 gene. This novel finding, correlating infection with epigenetic alterations, provides a mechanism linking environmental signals to placental phenotype, with conseque...

Infection and Immunity, 2003

Our previous animal studies showed that maternal Porphyromonas gingivalis infection in a subcutan... more Our previous animal studies showed that maternal Porphyromonas gingivalis infection in a subcutaneous chamber is associated with hepatic and uterine translocation, as well as systemic induction of maternal inflammatory responses, both of which were associated with fetal growth restriction (FGR). However, P. gingivalis- challenged dams had fetuses with either FGR (2 standard deviations below mean weight of nonchallenged dams) or normal weight. Therefore, the objective of this study was to determine whether maternal infection with P. gingivalis compromises normal fetal development via direct placental invasion and induction of fetus-specific placental immune responses characterized by a proinflammatory Th1-type cytokine profile. P. gingivalis -specific DNA was detected in placentas and fetuses of FGR and normal littermates from P. gingivalis -infected dams. Th1- and Th2-type cytokine mRNA as well as tumor necrosis factor alpha and transforming growth factor β2 mRNA were examined in pl...