The influence of prevalent cohort bias in the association between periodontal disease progression and incident coronary heart disease

Periodontitis is associated with an increased hazard of mortality in a longitudinal cohort study over 50 years

AIM

To evaluate the association between periodontal disease and all-cause mortality in a longitudinal cohort study over 50 years.

MATERIALS AND METHODS

Participants (N = 1156) in the Veterans Affairs Dental Longitudinal Study, aged 25-85 years at enrollment in 1968, received comprehensive medical and oral exams approximately every 3 years through 2007. Periodontal status was defined using person-level, mean whole-mouth radiographic alveolar bone loss (ABL) scores using a five-point Schei ruler, each unit representing 20% increments of ABL. Time-varying Cox regression models estimated hazard ratios (HRs) for the association between continuous and categorical ABL and mortality, adjusting for covariates.

RESULTS

Each one-unit increase in mean ABL score was associated with a 14% increase in the hazard of mortality (adjusted HR = 1.14, 95% confidence interval [CI] 1.02, 1.27). When assessed categorically, HRs for average scores of 2 to <3 and 3 to ≤5 showed increasing associations with hazard of mortality, relative to 0 to <1 (adjusted HR = 1.17, 95% CI 0.94, 1.46; and HR = 1.65, 95% CI 0.94, 2.85, respectively). By contrast, we observed null associations for average scores of 1 to <2 relative to 0 to <1 (adjusted HR = 1.00, 95% CI 0.86, 1.17).

CONCLUSIONS

Time-varying periodontal status assessed using radiographic ABL was positively associated with all-cause mortality even after confounder adjustment.

Cancer and diabetes co-occurrence: A national study with 44 million person-years of follow-up

The number of new cases of cancer is increasing each year, and rates of diabetes mellitus are also increasing dramatically over time. It is not an unusual occurrence for an individual to have both cancer and diabetes at the same time, given they are both individually common, and that one condition can increase the risk of the other. In this manuscript, we use national-level diabetes (Virtual Diabetes Register) and cancer (New Zealand Cancer Registry) data on nearly five million individuals over 44 million person-years of follow-up to examine the occurrence of cancer amongst a national prevalent cohort of patients with diabetes. We completed this analysis separately by cancer for the 24 most commonly diagnosed cancers in Aotearoa New Zealand, and then compared the occurrence of cancer among those with diabetes to those without diabetes. We found that the rate of cancer was highest amongst those with diabetes for 21 of the 24 most common cancers diagnosed over our study period, with excess risk among those with diabetes ranging between 11% (non-Hodgkin's lymphoma) and 236% (liver cancer). The cancers with the greatest difference in incidence between those with diabetes and those without diabetes tended to be within the endocrine or gastrointestinal system, and/or had a strong relationship with obesity. However, in an absolute sense, due to the volume of breast, colorectal and lung cancers, prevention of the more modest excess cancer risk among those with diabetes (16%, 22% and 48%, respectively) would lead to a substantial overall reduction in the total burden of cancer in the population. Our findings reinforce the fact that diabetes prevention activities are also cancer prevention activities, and must therefore be prioritised and resourced in tandem.

Generating depth images of preterm infants in given poses using GANs

BACKGROUND AND OBJECTIVES

The use of deep learning for preterm infant's movement monitoring has the potential to support clinicians in early recognizing motor and behavioural disorders. The development of deep learning algorithms is, however, hampered by the lack of publicly available annotated datasets.

METHODS

To mitigate the issue, this paper presents a Generative Adversarial Network-based framework to generate images of preterm infants in a given pose. The framework consists of a bibranch encoder and a conditional Generative Adversarial Network, to generate a rough image and a refined version of it, respectively.

RESULTS

Evaluation was performed on the Moving INfants In RGB-D dataset which has 12.000 depth frames from 12 preterm infants. A low Fréchet inception distance (142.9) and an inception score (2.8) close to that of real-image distribution (2.6) are obtained. The results achieved show the potentiality of the framework in generating realistic depth images of preterm infants in a given pose.

CONCLUSIONS

Pursuing research on the generation of new data may enable researchers to propose increasingly advanced and effective deep learning-based monitoring systems.

Edentulism is associated with increased risk of all-cause mortality in adult men

BACKGROUND

Prior reports of positive associations between edentulism and all-cause mortality have been limited by onetime assessments of edentulism and inadequate control of known confounding variables. The authors aimed to assess the association between edentulism and mortality using a longitudinal clinical oral health cohort.

METHODS

The authors used data from the Department of Veterans Affairs Dental Longitudinal Study, an ongoing, closed-panel cohort study from 1968 through 2019 (N = 1,229). Dentition status was evaluated through triennial clinical examinations. Mortality was assessed via the National Death Registry. The authors used Cox regression models to estimate the association between edentulism and all-cause mortality after covariate adjustment. Furthermore, the authors calculated propensity scores and assessed hazard ratios (HRs) in a trimmed, matched, and inverse probability weighted sample.

RESULTS

Participants who were edentulous (N = 112) had 1.24 (95% CI, 1.00 to 1.55) times the hazard of all-cause mortality compared with those who were nonedentulous, after adjustment with time-varying covariates. Use of propensity scores in the model resulted in slightly elevated HRs compared with the standard Cox model, regardless of propensity score method; adjusted HRs were 1.35 (95% CI, 1.01 to 1.80) after matching, 1.26 (95% CI, 1.00 to 1.59) after trimming, and 1.29 (95% CI, 1.18 to 1.42) after inverse probability weighting.

CONCLUSIONS

Edentulism was associated with an increased risk of all-cause mortality in a cohort that captured incident edentulism. This association was consistent after multiple methods to account for confounding.

PRACTICAL IMPLICATIONS

The findings of this study suggest that edentulism is associated with an increase in risk of mortality, after accounting for salient confounding variables using multiple approaches. Efforts to improve equitable access to tooth-preserving treatments are critical.

Testing the association between tobacco smoking, alcohol consumption, and risk of periodontitis: A Mendelian randomization study

AIM

To investigate the associations of tobacco smoking and alcohol consumption with periodontitis using Mendelian randomization (MR) analysis.

MATERIALS AND METHODS

We used 17 single nucleotide polymorphisms (SNPs) as instrumental variables (IVs) for the number of cigarettes per day from a genome-wide association study (GWAS) of 337,334 individuals, 109 SNPs for a lifetime smoking index from GWAS of 462,690 participants, and 33 SNPs for the number of drinks per week from GWAS of 941,280 individuals. The periodontitis GWAS included 12,289 cases and 22,326 controls. Wald ratios were obtained by dividing the SNP-periodontitis effects by SNP-exposure effects and pooled using an inverse-variance weighted model.

RESULTS

Genetic liabilities for higher number of cigarettes per day (odds ratio [OR] per one standard deviation (1SD) increment = 1.56; 95% CI: 1.18-2.07, p-value = .0018, Q-value = .0054), lifetime smoking index (OR per 1SD = 1.26; 95% CI: 1.04-1.53, p-value = .0161, Q-value = .0242), and drinks per week (OR per 1SD = 1.41; 95% CI: 1.04-1.90, p-value = .0265, Q-value = .0265) were associated with increased odds of periodontitis. Estimates were consistent across robust and multivariable MR analyses.

CONCLUSIONS

The findings of this MR analysis suggest an association between tobacco smoking and alcohol consumption with periodontitis.

Association Between Periodontal Disease and Atherosclerotic Cardiovascular Diseases: Revisited

Atherosclerotic cardiovascular disease (ACVD) is an inflammatory disease of the coronary arteries associated with atheroma formation, which can cause disability and often death. Periodontitis is ranked as the sixth most prevalent disease affecting humans affecting 740 million people worldwide. In the last few decades, researchers have focused on the effect of periodontal disease (PD) on cardiovascular disease. The aim of this review was to investigate the association between these two diseases. PD is a potential risk factor that may initiate the development, maturation, and instability of atheroma in the arteries. Two mechanisms were proposed to explain such association, either periodontal pathogens directly invade bloodstream or indirectly by increasing systemic level of inflammatory mediators. Interestingly, it has been suggested that improvement in the condition of one disease positively impact the condition of the other one. Highlighting the association between these two diseases, the importance of early diagnosis and treatment of PD and its impact on cardiovascular status may be of great value in reducing the complications associated with ACVDs. Further in vitro and in vivo studies with longer follow up are necessary to confirm the causal relationship between PD and ACVDs.

A quantitative bias analysis to assess the impact of unmeasured confounding on associations between diabetes and periodontitis

AIM

To investigate unmeasured confounding in bidirectional associations between periodontitis and diabetes using quantitative bias analysis.

METHODS

Subsamples from the Veterans Affairs Dental Longitudinal Study were selected. Adjusted for known confounders, we used Cox proportional hazards models to estimate associations between pre-existing clinical periodontitis and incident Type II Diabetes (n = 672), and between pre-existing diabetes and incident severe periodontitis (n = 521), respectively. Hypothetical confounders were simulated into the dataset using Bernoulli trials based on pre-specified distributions of confounders within categories of each exposure and outcome. We calculated corrected hazard ratios (HR) over 10,000 bootstrapped samples.

RESULTS

In models using periodontitis as the exposure and incident diabetes as the outcome, adjusted HR = 1.21 (95% CI: 0.64-2.30). Further adjustment for simulated confounders positively associated with periodontitis and diabetes greatly attenuated the association or explained it away entirely (HR = 1). In models using diabetes as the exposure and incident periodontitis as the outcome, adjusted HR = 1.35 (95% CI: 0.79-2.32). After further adjustment for simulated confounders, the lower bound of the simulation interval never reached the null value (HR ≥ 1.03).

CONCLUSIONS

Presence of unmeasured confounding does not explain observed associations between pre-existing diabetes and incident periodontitis. However, presence of weak unmeasured confounding eliminated observed associations between pre-existing periodontitis and incident diabetes. These results clarify the bidirectional periodontitis-diabetes association.

Oral Health and Cardiovascular Disease: Mapping Clinical Heterogeneity and Methodological Gaps

BACKGROUND

Numerous studies have examined the associations between poor oral health and the incidence of cardiovascular disease (CVD) over the past 25 y. This long history of research has resulted in a broad and heterogenous epidemiological field whose implications are difficult to understand and whose methodological gaps are hard to track.

OBJECTIVES

This systematic mapping review aims to systematically map clinical heterogeneity and methodological gaps in assessing the relationship between poor oral health and CVD outcomes.

METHODS

Medline, Embase, and Cochrane Library were searched to identify longitudinal studies that examined the relationship between any oral health indicator and CVD outcomes. Each database was searched from its inception date and June 27, 2018. Extracted data assess the clinical heterogeneity (participants' characteristics, exposure and outcome measures, length of follow-up) and methodological gaps (availability of randomized controlled trials, utilization of time-varying exposures, propensity methods, mediation analysis, and competing risks analysis).

RESULTS

Eighty-five studies met the inclusion criteria. Clinical heterogeneity is evident in participants' characteristics (age, clinical status, and occupation) and in the definitions of oral health indicators and CVD outcomes. More important, a significant proportion of studies reported unclear definitions for CVD outcomes. The search strategy did not reveal any randomized controlled trials. Time-varying exposures, propensity methods, mediation analysis, and competing risks analysis are used infrequently in the identified studies.

CONCLUSION

There is a need for a universally accepted conceptual framework on the association between oral health and CVD to derive more consistent definitions for oral health and CVD outcomes that are aligned with the investigated research questions. There is also a need to use emerging research methods to maximize the impact of research in this area.

KNOWLEDGE TRANSFER STATEMENT

Clinical heterogeneity is evident in the definitions of oral health indicators and cardiovascular disease outcomes. Propensity methods, mediation analysis, and competing risks analysis are used infrequently in the identified studies. The identified clinical heterogeneity and methodological gaps interfere with summarizing existing evidence and understanding their practical implications. Advancing the current understanding of the associations between oral health and cardiovascular disease goes hand in hand with minimizing clinical heterogeneity and closing the identified methodological gaps.

Periodontal diseases and association with atherosclerotic disease

Cardiovascular diseases still account for the majority of deaths worldwide, although significant improvements in survival, after being affected by cardiovascular disease, have been achieved in the last decades. Periodontal diseases are also a common global burden. Several studies have shown a link between cardiovascular disease and periodontitis, although evidence is still lacking regarding the direct cause-effect relation. During the 2012 "Periodontitis and systemic diseases" workshop, the available evidence on the association between cardiovascular and periodontal diseases was discussed, covering biologic plausibility and clinical studies. The objective of the present narrative review was to update the previous reviews presented at the 2012 workshop, following similar methodological approaches, aiming to critically assess the available evidence. With regard to biologic plausibility, two aspects were reviewed: (a) for microbiologic mechanisms, assessing periodontal bacteria as a contributing factor to atherosclerosis based on seven "proofs," substantial evidence was found for Proofs 1 through 6, but not for Proof 7 (periodontal bacteria obtained from human atheromas can cause atherosclerosis in animal models), concluding that periodontal pathogens can contribute to atherosclerosis; (b) mechanistic studies, addressing five different inflammatory pathways that could explain the links between periodontitis and cardiovascular disease with the addition of some extra pathways , suggest an association between both entities, based on the presence of higher levels of these inflammatory markers in patients with periodontitis and cardiovascular disease, vs healthy controls, as well as on the evidence that periodontal treatment reduces serum levels of these mediators. When evidence from clinical studies was analyzed, two aspects were covered: (a) epidemiologic studies support the estimation that the incidence of atherosclerotic disease is higher in individuals with periodontitis than in individuals with no reported periodontitis, irrespective of many common risk factors, but with a substantial variability in the definitions used in reporting of exposure to periodontal diseases in different studies; (b) intervention trials have shown that periodontal therapy can reduce serum inflammatory mediators, improve the lipids profile, and induce positive changes in other cardiovascular disease surrogate measures, but no evidence is available to support that adequate periodontal therapy is able to reduce the risk for cardiovascular diseases, or the incidence of cardiovascular disease events in periodontitis patients.

Fish oil diet effects on alveolar bone loss, in hypercholesterolemic rats

This study evaluated the effects of replacing a saturated fat diet by n-3 polyunsaturated fatty acids (n-3PUFA), on alveolar bone loss in hypercholesterolemic rats with experimental periodontitis (PD).

METHODS

Eight week old Wistar rats were assigned according to dietary intake. Control group (C, n = 15) fed a commercial diet throughout the experiment. Atherogenic group (AT, n = 30) fed AT diet for 3 weeks; thereafter, AT was randomized to receive either a n-3PUFA (n = 15) or to continue with AT (n = 15) diet. Subsequently, PD was induced in all groups by unilateral ligature (L) of the first molar (M1) of the left mandible, non-ligated contralateral molars served as controls. After every week of PD induction, 5 rats per group were euthanized. Serum was collected for lipids assays and hemi-mandibles were subjected to histomorphometric (% upper and lower interradicular bone volume and periodontal ligament height, hPDL) and radiographic analyses (periodontal bone support, PBS, in ligated teeth, between M1-M2).

RESULTS

Rats fed n-3PUFA diet rapidly induced a significant reduction in the serum lipids (p < 0.001). In all rats the ligated teeth showed a greater bone loss as compared with the unligated molars. At the end of the experiment the AT + L was the worst in % lower bone volume (p < 0.01), hPDL and PBS (p < 0.05). In contrast, rats fed n-3PUFA + L was similar to those rats fed C diet (p > 0.05).

CONCLUSION

Alveolar bone and dyslipidemia improved by substituting saturated fat intake for a n-3PUFA rich diet, in hypercholesterolemic rats with PD.

Proton Pump Inhibitors and Infant Pneumonia/Other Lower Respiratory Tract Infections: National Nested Case-control Study

OBJECTIVE

The possible association between the use of proton pump inhibitors (PPIs) and community-acquired pneumonia (CAP) or another lower respiratory tract infection (LRTI) remains uncertain. We conducted a nested case-control study using routinely collected national health and drug dispensing data in New Zealand to examine the risk of CAP or another LRTI resulting in hospitalization or death in infants dispensed a PPI.

STUDY DESIGN

The cohort included 21,991 patients without a history of CAP or another LRTI who were born between 1 January 2005 and 31 December 2012 and were dispensed omeprazole, lansoprazole, or pantoprazole (the PPIs available in New Zealand during the study period) on at least one occasion during the first year of life. Cases had a first diagnosis after cohort entry (first PPI dispensing) of CAP (n = 65) validated by hospital discharge letter or death record, and chest radiography; or LRTI (including CAP) (n = 566) validated by hospital discharge letter or death record, with or without chest radiography. Up to 10 controls, matched by sex and date of birth, were randomly selected for each case. We conducted complete case analyses for the fully adjusted models.

RESULTS

In the adjusted analysis based on CAP cases and their controls, the matched odds ratio for current versus past use of PPIs was 0.88 (95% confidence interval 0.36-2.16). For all LRTI cases and their controls, the matched odds ratio was 1.13 (0.87-1.48).

CONCLUSION

In otherwise healthy community-dwelling infants, current use of a PPI does not appear to increase the risk of CAP or other LRTIs.

Possible association between obesity and periodontitis in patients with Down syndrome

BACKGROUND

The present study was carried out to evaluate the possible association between obesity and periodontitis in patients with DS, and to explore which measure of obesity is most closely correlated to periodontitis.

MATERIAL AND METHODS

A prospective observational study was made to determine whether obesity is related to periodontal disease in patients with DS. The anthropometric variables were body height and weight, which were used to calculate BMI and stratify the patients into three categories: < 25(normal weight), 25-29.9 (overweight) and ≥ 30.0 kg/m2 (obese). Waist circumference and hip circumference in turn was recorded as the greatest circumference at the level of the buttocks, while the waist/hip ratio (WHR) was calculated. Periodontal evaluation was made of all teeth recording the plaque index (PI), pocket depth (PD), clinical attachment level (CAL) and the gingival index. We generated a multivariate linear regression model to examine the relationship between PD and the frequency of tooth brushing, gender, BMI, WHI, WHR, age and PI.

RESULTS

Significant positive correlations were observed among the anthropometric parameters BMI, WHR, WHI and among the periodontal parameters PI, PD, CAL and GI. The only positive correlation between the anthropometric and periodontal parameters corresponded to WHR. Upon closer examination, the distribution of WHR was seen to differ according to gender. Among the women, the correlation between WHR and the periodontal variables decreased to nonsignificant levels. In contrast, among the males the correlation remained significant and even increased. In a multivariate linear regression model, the coefficients relating PD to PI, WHR and age were positive and significant in all cases.

CONCLUSIONS

Our results suggest that there may indeed be an association between obesity and periodontitis in male patients with DS. Also, we found a clear correlation with WHR, which was considered to be the ideal adiposity indicator in this context.

Metabolic syndrome as a risk factor for total hip or knee replacement due to primary osteoarthritis: a prospective cohort study (the HUNT study and the Norwegian Arthroplasty Register)

Objective

Biochemical changes associated with obesity may accelerate osteoarthritis beyond the effect of mechanical factors. This study investigated whether metabolic syndrome and its components (visceral obesity, hypertension, dyslipidemia and insulin resistance) were risk factors for subsequent total hip replacement (THR) or total knee replacement (TKR) due to primary osteoarthritis.

Design

In this prospective cohort study, data from the second survey of the Nord-Trøndelag Health Study 2 (HUNT2) were linked to the Norwegian Arthroplasty Register for identification of the outcome of THR or TKR. The analyses were stratified by age (<50, 50–69.9 and ≥70 years) and adjusted for gender, body mass index, smoking, physical activity and education.

Results

Of the 62,661 participants, 12,593 (20.1%) were identified as having metabolic syndrome, and we recorded 1,840 (2.9%) THRs and 1,111 (1.8%) TKRs during a mean follow-up time of 15.4 years. Cox regression analyses did not show any association between full metabolic syndrome and THR or TKR, except in persons <50 years with metabolic syndrome who had a decreased risk of THR (hazard ratio [HR] 0.58, 95% CI 0.40–0.83). However, when including only participants whose exposure status did not change during follow-up, this protective association was no longer significant. Increased waist circumference was associated with increased risk of TKR in participants <50 years (HR 1.62, 95% CI 1.10–2.39) and 50–69.9 years (HR 1.43, 95% CI 1.14–1.80). Hypertension significantly increased the risk of TKR in participants <50 years (HR 1.38, 95% CI 1.05–1.81), and this risk was greater for men.

Conclusion

This study found an increased risk of TKR in men <50 years with hypertension and persons <70 years with increased waist circumference. Apart from this, neither metabolic syndrome nor its components were associated with increased risk of THR or TKR due to primary osteoarthritis.

Premature Death Among Primary Care Patients With a History of Self-Harm

PURPOSE

Self-harm is a public health problem that requires a better understanding of mortality risk. We undertook a study to examine premature mortality in a nationally representative cohort of primary care patients who had harmed themselves.

METHODS

During 2001-2013, a total of 385 general practices in England contributed data to the Clinical Practice Research Datalink with linkage to Office for National Statistics mortality records. We identified 30,017 persons aged 15 to 64 years with a recorded episode of self-harm. We estimated the relative risks of all-cause and cause-specific natural and unnatural mortality using a comparison cohort of 600,258 individuals matched on age, sex, and general practice.

RESULTS

We found an elevated risk of dying prematurely from any cause among the self-harm cohort, especially in the first year of follow-up (adjusted hazard ratio for that year, 3.6; 95% CI, 3.1-4.2). In particular, suicide risk was especially high during the first year (adjusted hazard ratio, 54.4; 95% CI, 34.3-86.3); although it declined sharply, it remained much higher than that in the comparison cohort. Large elevations of risk throughout the follow-up period were also observed for accidental, alcohol-related, and drug poisoning deaths. At 10 years of follow-up, cumulative incidence values were 6.5% (95% CI, 6.0%-7.1%) for all-cause mortality and 1.3% (95% CI, 1.2%-1.5%) for suicide.

CONCLUSIONS

Primary care patients who have harmed themselves are at greatly increased risk of dying prematurely by natural and unnatural causes, and especially within a year of a first episode. These individuals visit clinicians at a relatively high frequency, which presents a clear opportunity for preventive action. Primary care patients with myriad comorbidities, including self-harming behavior, mental disorder, addictions, and physical illnesses, will require concerted, multipronged, multidisciplinary collaborative care approaches.

Salivary Lipid Peroxidation in Patients With Generalized Chronic Periodontitis and Acute Coronary Syndrome

BACKGROUND

Lipid peroxidation is a major consequence of oxidative stress and can be evaluated via malondialdehyde (MDA) levels. The present study aims to assess MDA levels in the saliva of patients with chronic periodontitis (CP) and acute coronary syndrome (ACS) and establish their correlation with periodontal clinical parameters, serum high-sensitivity C-reactive protein (hsCRP), and plasma fibrinogen.

METHODS

The study enrolled 64 patients stratified into four age- and sex-matched groups: both ACS and CP, ACS only, CP only, and healthy controls. All patients were examined, periodontal clinical parameters were recorded, and saliva and blood samples were collected. Salivary MDA levels were measured using a spectrophotometric assay. A quantitative turbidimetric test was used for the measurement of serum hsCRP levels, and plasma fibrinogen levels were determined using an automated analyzer.

RESULTS

Salivary MDA levels were significantly higher in patients with both ACS and CP than in those with only ACS or only CP and healthy controls (P <0.05). There were significant positive correlations between salivary MDA levels and periodontal clinical parameters as well as biomarkers for cardiovascular events (P <0.001).

CONCLUSIONS

To our knowledge, this study is the first to investigate salivary MDA levels in patients with ACS and their correlations with serum hsCRP and plasma fibrinogen levels. The results indicate that salivary MDA levels could be a biomarker for cardiovascular and/or periodontal disease.

Is weight gain associated with the incidence of periodontitis? A systematic review and meta-analysis

AIM

This study aimed to conduct a systematic review assessing the effects of weight gain on the incidence of periodontitis in adults.

METHODS

Electronic searches in four databases were performed up to and including February 2015. Only prospective longitudinal studies assessing the association between weight gain and the incidence of periodontitis in adults were eligible to be included in this study. All studies should state a clear description of nutritional status (Body Mass Index; Waist Circumference) as well as the case definition of periodontitis. Pooled relative risks (RR) for becoming overweight and obese on the incidence of periodontitis were estimated by meta-analysis. Quality was assessed with the Newcastle-Ottawa scale for cohort studies.

RESULTS

Five articles were included in this review and meta-analysis with 42,198 subjects enrolled. Subjects who became overweight and obese presented higher risk to develop new cases of periodontitis (RR 1.13; 95%CI 1.06-1.20 and RR 1.33 95%CI 1.21-1.47 respectively) compared with counterparts who stayed in normal weight.

CONCLUSIONS

A clear positive association between weight gain and new cases of periodontitis was found. However, these results are originated from limited evidence. Thus, more studies with longitudinal prospective design are needed.