Apical Periodontitis and Diabetes Mellitus Type 2: A Systematic Review and Meta-Analysis

An exploratory study to understand the relationship between diabetes and various pulpal conditions: An Indian perspective

Aim

Diabetes mellitus (DM) affects an estimated 100 million Indians, ranking second globally in diabetic prevalence. Despite this, the correlation between DM and specific pulpal diagnoses remains underexplored. This study compares pulpal conditions in DM patients and nondiabetic controls.

Designs

The study was started after taking ethical approval.

Subjects and Methods

Two thousand and five hundred and sixty teeth were examined over 4 months at the institute, evenly distributed between diabetic and nondiabetic cases, we assessed diagnoses - normal pulp, reversible pulpitis (RP), symptomatic irreversible pulpitis, asymptomatic irreversible pulpitis, pulp necrosis (PN), missing teeth (MT), and root canal-treated teeth (RCT). Statistical analysis used the Chi-square test.

Results

PN and MT prevalence in DM patients significantly exceeded the control group. Conversely, the control group showed higher RP prevalence in the older subgroup.

Conclusions

PN prevalence was higher in diabetics, suggesting reduced pulp sensitivity in individuals over 60 years. This diminished sensitivity might lead to delayed dental treatment, increasing PN prevalence.

Successful endodontic treatment reduces serum levels of cardiovascular disease risk biomarkers-high-sensitivity C-reactive protein, asymmetric dimethylarginine, and matrix metalloprotease-2

AIM

To investigate serum biomarkers of inflammation 2 years following non-surgical root canal re-treatment (Re-RCT) and peri-apical surgery (PS). The results were correlated with signs and symptoms, treatment outcome, metabolic syndrome factors, infection with severe acute respiratory syndrome coronavirus 2 SARS-CoV-2 (COVID-19) infection and COVID-19 vaccination.

METHODOLOGY

Subjects from our previous study were recalled for 2 years post-treatment follow-up. Changes to the patient's history (medical, dental, social) were noted. Periapical health of the treated teeth was examined both clinically and radiographically. Blood pressure, fasting HbA1C and low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides and total cholesterol (TC) levels were measured. Serum inflammatory marker levels were assayed using a Bio-Rad Bio-Plex 200 analyser and values at different time points within the same group were compared using a Wilcoxon signed-rank test and differences between groups with a Mann-Whitney test. Linear associations were tested using Pearson's correlations.

RESULTS

The recall percentage at 2 years was 56.9% (n = 37), with a 100% radiographic success rate using periapical radiographs. In total, 21 cases (56.8%) were completely healed, and 16 cases (43.2%) were healing. Higher matrix metalloprotease 2 (MMP2) levels were present in the healing group compared to the healed group. Serum levels of high-sensitivity C-reactive protein (hs-CRP), asymmetric dimethylarginine (ADMA) and MMP-2 were significantly reduced (p ≤ .001) whereas other biomarkers showed significant increases at 2 year compared to pre-operative levels, while FGF-23 and ICAM-1 were not significantly increased. HbA1C (p = .015), TC (p = .003), LDL (p = .003) and HDL (p = .003) reduced significantly at 2 years post-treatment compared to their preoperative levels. COVID infection showed a significant association with MMP-9 (p = .048).

CONCLUSIONS

hs-CRP, ADMA and MMP-2 can be regarded as prognostic biomarkers of successful Re-RCT and PS as they reduced at 2 year recall in cases which showed evidence of clinical and radiographic success. The successful treatment of chronic apical periodontitis is correlated with improvements in metabolic syndrome indicators, better glycemic control, and reduction at 2 year of some systemic inflammatory markers which are related to risks of cardiovascular disease events.

Effects of Nd: YAG laser on tumour necrosis factor-alpha, interleukin-1beta and interferon-gamma levels in teeth with apical periodontitis: A clinical study

This study aimed to evaluate the levels of tumour necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β) and interferon-gamma (IFN-γ) with asymptomatic apical periodontitis (AP). A total of 60 participants were randomly divided into two groups: the conventional irrigation (control) and the Nd: YAG laser irradiation. The interstitial fluids were obtained after root canal cleaning (day 0) and 1 week later (day 7). The TNF-α, IL-1β and IFN-γ levels were assayed using the enzyme-linked immunosorbent assay. The Mann-Whitney U, continuity correction chi-square, Pearson chi-square and Fisher exact tests were used. An increased level of cytokines on day 7 in the control group was observed, without statistically significant differences (p > 0.05). All cytokine levels decreased over time in the laser group. Only the IL-1β level showed a significant difference (p < 0.05). Nd: YAG irradiation has a positive effect on decreasing the proinflammatory cytokine level and may help to control infection in teeth with AP.

Diabetes Mellitus Increases the Risk of Apical Periodontitis in Endodontically-Treated Teeth: A Meta-Analysis from 15 Studies

INTRODUCTION

At present, the incidence of diabetes mellitus (DM) is gradually increasing globally. In clinical practice, many patients with diabetes with apical periodontitis (AP) have poor and slow healing of periapical lesions. However, the potential relationship between the 2 is still unclear and controversial. The consensus is that DM can be deemed a risk factor for AP in endodontically-treated teeth. Therefore, we pooled existing studies and carried out a meta-analysis to explore the potential association between the 2.

METHODS

Studies that met the inclusion criteria were selected from the database, and relevant data were extracted. Stata SE 17.0 software was used to analyze the relevant data, and the Newcastle-Ottawa Scale was used to assess the literature's quality. The pooled odds ratio (OR) with a 95% confidence interval (CI) was used to determine the strength of the association between DM and the prevalence of AP after root canal treatment (RCT).

RESULTS

After searching, 262 relevant studies were retrieved, fifteen of which met the inclusion criteria. A total of 1087 patients with 2226 teeth were included in this meta-analysis. According to the findings, diabetics showed a higher prevalence of AP after RCT than controls at the tooth level (OR = 1.51, 95% CI = 1.22-1.87, P < .01). At the patient level, DM increased the probability of developing AP in RCT teeth more than 3 times (OR = 3.38, 95% CI = 1.65-6.93, P < .01). Additionally, subgroup analysis was performed by blood glucose status, preoperative AP, and study design. Except for the status of blood glucose, the results were significant in the other 2 groups (P < .05).

CONCLUSIONS

Available scientific evidence suggests that DM may increase the risk of AP in endodontically-treated teeth. In teeth with preoperative AP, DM might promote the development of AP.

Effect of endodontic treatment on clinical outcome in type 2 diabetic patients with apical periodontitis

Background

Previous research has demonstrated that poor controlled diabetic showed higher prevalence of AP compared to well-controlled patients and endodontic treatment may improve metabolic control of patients with diabetes. The purpose of this trial was to clinically assess the effects of endodontic treatment on glycemic control in patients with type 2 diabetes mellitus (T2DM) and apical periodontitis (AP).

Study design

For present trial, AP + T2DM with patients insulin injection (Group1, G1,n = 65), AP + T2DM patients with hypoglycaemic agents (Group2, G2, n = 82), and AP patients without DM (Group3, G3, n = 86) were enrolled. After demographic characteristics and clinical examination were achieved, root canal treatment (RCT) was performed for each patient. Subjects were followed up at 2-week, 3- and 6-month. At each visit, blood samples were taken and clinical laboratory studies were performed. At 6-month follow-up, Periapical Index (PAI) score was used to assess the periapical status.

Results

A total of 237 subjects who met the including criteria were allocated in three groups and 223 subjects (94.1%) completed the treatments and the follow-up assessments. After treatment, taking PAI into consideration, both groups showed significant improvement of AP in each group (P < 0.05). Patients in G3 had a continued significant lower concentration of fasting plasma glucose (FPG) levels at follow-up (P < 0.05). A continued reduction of hemoglobin glycation (HbA1c) was observed in most of time points (P < 0.05). Throughout the trial, there are also significant changes in inflammatory factors in short-term.

Conclusion

Endodontic therapy improved AP healing, glycemic control and systemic inflammation in patients with T2DM and/or AP in each group. However, a continued reduction in inflammatory factors and decreasing of HbA1c in short-term could not be observed in this trial.

Poor dental health and risk of pancreatic cancer: a nationwide registry-based cohort study in Sweden, 2009-2016

BACKGROUND

Previous studies have reported inconsistent results regarding the association between poor dental health and pancreatic cancer risk. This study aimed to assess this association using a well-functioning nationwide dental health registry in Sweden.

METHODS

Information of exposures (dental caries, root canal infection, mild inflammation, and periodontitis; the number of teeth) was ascertained from the Swedish Dental Health Register, and occurrence of pancreatic cancer was identified from both cancer and cause of death registries. Hazard ratios (HRs) were estimated using Cox models.

RESULTS

During a median of 7.2 years of follow-up, 10,081 pancreatic cancers were identified among 5,889,441 individuals. Compared with the healthy status, a higher risk of pancreatic cancer was observed in individuals with root canal infection, mild inflammation, and periodontitis in the <50 age group (P for trend <0.001). In the 50-70 age group, only the subgroup with periodontitis had an excess risk (multivariable-adjusted HR = 1.20, 95% confidence interval [CI] 1.11-1.29). No positive association with statistical significance was observed in the 70+ age group. Individuals with fewer teeth tended to have a higher risk in all age groups.

CONCLUSIONS

Our results confirmed the association between poor dental health and pancreatic cancer risk, which warrants further studies on underlying mechanisms.

Chronic Obstructive Pulmonary Disease and Apical Periodontitis and Other Oral Health Variables: A Case-Control Study

Background: The relationship between chronic inflammatory diseases and their comorbidities and correlation with periodontal diseases has become an increasing focus of research. Objectives: The aim of this case-control study was to conclude if patients suffering from COPD (Chronic Obstructive Pulmonary Disease) tend to have more AP (Apical Periodontitis) than non-COPD patients. Materials and Methods: The study was conducted on 30 patients assigned as cases, associated with 30 control patients linked by age (+/−5 years) and sex. Results: A total of 60 patients were recorded, and a total of 12 radiographic variables were analyzed. A total of 43 (71.7%) patients were registered with PAI (Periapical Index) ≥ 3, and there was a slightly tendency in the patients from the control group 22 (73.3%) compared to those from the cases 21 (70%), respectively (p > 0.05). Conclusions: It was concluded that there was not a significant association between the levels of PAI (Periapical Index) ≥ 3 per patient in those suffering from COPD. In fact, it could be concluded that patients diagnosed with COPD tend to have more teeth with PAI ≥ 3, more endodontic treatments and their periodontitis tended to accumulate more caries. Clinical Significance: This study establishes, in a case-control study, some specific aspects of oral health in patients with COPD, as well as analyzing the importance of oral health in this disease.

Association between Endodontic Infection, Its Treatment and Systemic Health: A Narrative Review

The 'Focal Infection Era in Dentistry' in the late 19th and early 20th century resulted in widespread implementation of tooth extraction and limited the progress of endodontics. The theory proposed that bacteria and toxins entrapped in dentinal tubules could disseminate systemically to remote body parts, resulting in many types of degenerative systemic diseases. This theory was eventually refuted due to anecdotal evidence. However, lately there has been increased interest in investigating whether endodontic disease could have an impact on general health. There are reviews that have previously been carried out on this subject, but as new data have emerged since then, this review aims to appraise the available literature investigating the dynamic associations between apical periodontitis, endodontic treatment, and systemic health. The available evidence regarding focal infection theory, bacteraemia and inflammatory markers was appraised. The review also collated the available research arguing the associations of apical periodontitis with cardiovascular diseases, diabetes mellitus, adverse pregnancy outcome and autoimmune disorders, along with the effect of statins and immunomodulators on apical periodontitis prevalence and endodontic treatment prognosis. There is emerging evidence that bacteraemia and low-grade systemic inflammation associated with apical periodontitis may negatively impact systemic health, e.g., development of cardiovascular diseases, adverse pregnancy outcomes, and diabetic metabolic dyscontrol. However, there is limited information supporting the effect of diabetes mellitus or autoimmune disorders on the prevalence and prognosis post endodontic treatment. Furthermore, convincing evidence supports that successful root canal treatment has a beneficial impact on systemic health by reducing the inflammatory burden, thereby dismissing the misconceptions of focal infection theory. Although compelling evidence regarding the association between apical periodontitis and systemic health is present, further high-quality research is required to support and establish the benefits of endodontic treatment on systemic health.

The impact of apical periodontitis, non-surgical root canal retreatment and periapical surgery on serum inflammatory biomarkers

AIM

The aim of the study was to measure serum levels of molecular markers of inflammation in patients undergoing non-surgical root canal retreatment (Re-RCT) and periapical surgery (PS) for the treatment of apical periodontitis and to establish if such levels are influenced by the size of apical radiolucencies at baseline and by the treatment outcome.

METHODOLOGY

A total of 115 participants were recruited (n = 50 Controls, n = 35 Re-RCT, n = 30 PS). Preoperative periapical radiographs and cone beam CT (CBCT) scans of teeth were taken. Blood was collected from treatment groups at baseline, 3-, 6-, and 12-month post-treatment and from controls at baseline and 12 months. Serum levels of IL-1β, IL-6, IL-8, TNF-α, Pentraxin 3, ICAM-1, VCAM-1, hs-CRP, FGF-23, MMP-2, MMP-8, MMP-9, C3 and ADMA were analysed using multiplex immunoassay and enzyme-linked immunosorbent assay. Different time points within the same group were compared using Wilcoxon signed-rank test, and differences between groups were analysed using the Mann-Whitney test. Non-linear association between different factors was assessed using Spearman's correlation.

RESULTS

Preoperative serum levels of FGF-23, IL-1β, hs-CRP and ADMA were significantly higher in the diseased groups compared with controls (p < .001; p = .008; p < .001; p = .013, respectively). The preoperative size of the radiolucency was associated with increased levels of FGF-23, IL-1β and IL-6. At 3-months following treatment, IL-1β, IL-8, hs-CRP, C3, MMP-2 and MMP-9 levels increased compared with baseline in treatment groups. IL-1β and IL-8 further increased at 6 months, whereas FGF-23, hs-CRP, C3, MMP2 and MMP-9 decreased. One-year post-treatment, FGF-23, pentraxin-3 and ADMA were significantly reduced below baseline levels. At the 1-year review, CBCT revealed that 25.9% of treated cases completely healed, while 63% were healing, and 11.1% failed. Treatment outcome was found to be influenced by preoperative levels of ADMA and IL-8 levels at 6 months.

CONCLUSIONS

Both symptomatic and asymptomatic apical periodontitis (AP) can contribute to increased levels of molecular markers of inflammation. A further transient inflammatory markers rise after root canal retreatment and apical surgery were demonstrated. Successful endodontic treatment and periapical surgery result in a long-term reduction in inflammatory marker levels.

Type 2 diabetes and the clinically normal pulp - An in-vitro study

Aim

The aim of this study was to investigate the effect of type 2 diabetes (T2D) on clinically normal dental pulp tissue by using special stains and immunohistochemistry (IHC) to determine the morphology of the coronal pulp and distribution of immune markers in non‐T2D and T2D groups.

Methodology

Ethics approval for this in vitro pilot study was obtained from the University of Otago Human Ethics Committee (16/069). Twenty extracted permanent molar teeth diagnosed as having clinically normal pulp status were collected. Ten teeth were from participants with well‐controlled T2D and ten from participants without diabetes (non‐T2D). Each tooth was sectioned transversely at the cemento‐enamel junction before the crowns were decalcified and embedded in paraffin. Sections were stained with haematoxylin and eosin, Massons trichrome, and van Gieson stains for histological and morphological evaluation. IHC using anti‐CD4, anti‐CD68 and anti‐CD83 and anti‐IL1β, anti‐IL6, anti‐IL17, anti‐TNF‐α, anti‐TLR2, anti‐TLR4 and anti‐FOXP3 identified proteins of interest. Qualitative and semi‐quantitative analyses evaluated the morphology of the dental pulp and protein expression. Data analyses were performed with GraphPad Prism, using Student's t‐test and multiple regression using SPSS at p < .05.

Results

Special stains demonstrated morphological differences in the T2D dental pulp compared with non‐T2D. Qualitative analysis indicated that the pulp in the T2D samples was consistently less cellular, less vascular, showed evidence of thickened blood vessel walls, increased pulp calcification and collagen deposition. Semi‐quantitative analysis of IHC samples showed the T2D pulp had significantly increased expression of macrophage and dendritic cell markers CD68 (p < .001) and CD83 (p = .04), and there was significantly greater expression of inflammatory cytokines IL1β (p = .01), IL6 (p < .0001), IL17 (p < .0001) and TNF‐α (p = .01). T2D samples showed a significant increase in markers of innate inflammation, TLR2 (p < .001) and TLR4 (p < .001) and decreased expression of regulatory T‐cell marker, FOXP3 (p = .01). Multiple regression showed that age‐corrected differences were statistically significant.

Conclusion

Preliminary findings suggest that T2D may exert a similar response in the pulp to complications in other body sites. Hyperglycaemia is associated with changes in the morphology of the clinically normal dental pulp with altered immune cell and cytokine expression.

Influence of small-group experiential learning of integrated traditional Chinese and Western medicine on the oral health knowledge, beliefs, and behaviors of elderly patients with diabetes

OBJECTIVE

This study aimed at the oral health problems of elderly patients with diabetes. A training course of integrated traditional Chinese and Western medicine was constructed, helping patients improve their oral health quality of life.

METHODS

A randomized controlled prospective experimental study was conducted. A total of 190 elderly patients were divided randomly into an observation group and a control group with 95 cases in each. The control group received regular health education, while the observation group was based on the control group to implement the integrated experiential learning of traditional Chinese and Western medicine in small groups. The oral health knowledge, attitude, behavior, and blood glucose control status along with the oral health quality of life of the two groups were compared before the intervention and at 3-month postintervention.

RESULTS

Three months after the intervention, the fasting blood glucose control and the 2-h postprandial blood glucose/glycosylated hemoglobin levels in the observation group were significantly better than in the control group, and the difference was statistically significant (p<0.05). The oral health quality of life in the observation group was significantly better than in the control group, and the difference was statistically significant (p<0.05).

CONCLUSION

The small-group experiential learning model of integrated Chinese and Western medicine can promote the transformation of knowledge-beliefs-behaviors in elderly patients with diabetes, which is conducive to controlling blood sugar levels and improving the quality of oral health.

Altered Prevalence of Pulp Diagnoses in Diabetes Mellitus Patients: A Retrospective Study

INTRODUCTION

Diabetes mellitus (DM) is a complex multisystemic disorder that affects an estimated 21 million Americans. No studies have evaluated the association of DM with the prevalence of each pulpal diagnosis. The objective of this study was to compare the prevalence of each pulp diagnosis including symptomatic irreversible pulpitis (SIP), asymptomatic irreversible pulpitis, reversible pulpitis, normal pulp, and pulp necrosis (PN) in DM patients against a nondiabetic control group.

METHODS

A retrospective chart review was approved by Rutgers University Institutional Review Board. The prevalence of the diagnoses SIP, asymptomatic irreversible pulpitis, reversible pulpitis, normal pulp, and PN was calculated from AxiUm (Exan software, Las Vegas, NV) electronic health records at Rutgers School of Dental Medicine. The chi-square test was used to see the relationship between the 2 categoric variables. Second, binary logistic regression analyses were performed for each group.

RESULTS

A total of 2979 teeth were diagnosed with a pulp condition between April 2013 and November 2018. The total tooth number of DM patients was 682, whereas the tooth number of nondiabetic patients was 2297. In the subgroup of patients younger than 40 years old, SIP was notably more prevalent in DM patients. In addition, the prevalence of PN in elderly DM patients (60-69 years old) was significantly higher than in the control group.

CONCLUSIONS

The prevalence of SIP in DM patients was significantly higher compared with the control group (<40 years old), suggesting the possibility that DM could hypersensitize the subgroup of patients younger than 40 years old to pulpitis pain.

microRNA-491-5p regulates osteogenic differentiation of bone marrow stem cells in type 2 diabetes

OBJECTIVES

Osseointegration of oral implants has a low success rate in patients with type 2 diabetes. This is because of the inhibition of osteogenic differentiation in the jawbone marrow mesenchymal stem cells, in which the expression of microRNA(miR)-491-5p is significantly downregulated, as ascertained through gene chip screening. However, the underlying mechanisms are unclear. Here, we aimed to clarify the mechanisms involved in the influence of miR-491-5p on osteogenic differentiation.

SUBJECTS AND METHODS

Jawbone marrow mesenchymal stem cells were isolated from jawbones of patients with type 2 diabetes and subjected to bioinformatics and functional analyses. Osteogenesis experiments were conducted using the isolated cells and an in vivo model.

RESULTS

Knockdown and overexpression experiments revealed the positive effects of miR-491-5p expression on osteogenic differentiation in vivo and in vitro. Additionally, a dual-luciferase assay revealed that miR-491-5p targeted the SMAD/RUNX2 pathway by inhibiting the expression of epidermal growth factor receptor.

CONCLUSIONS

miR-491-5p is vital in osteogenic differentiation of jawbone mesenchymal stem cells; its downregulation in type 2 diabetes could be a major cause of decreased osteogenic differentiation. Regulation of miR-491-5p expression could improve osteogenic differentiation of jawbone mesenchymal stem cells in patients with type 2 diabetes.

Synergistic effects of silver ions and metformin against enterococcus faecalis under high-glucose conditions in vitro

Background

This study aimed to evaluate the synergistic antibacterial activities of silver ions (Ag⁺) and metformin hydrochloride (Met) against Enterococcus faecalis (E. faecalis) under normal or high-glucose conditions.

Results

The minimum inhibitory concentration, minimum bactericidal concentration, growth curves, and colony-forming units were used to evaluate the antibacterial effects of Ag⁺ and Met on planktonic E. faecalis in Brain Heart Infusion broth with or without additional glucose. The influences of Ag⁺ and Met on four weeks E. faecalis biofilm on human dentin slices was also tested. Cytotoxicity was tested on MC3T3-E1 osteoblastic cells using CCK-8 assays. The results indicated that E. faecalis showed higher resistance to drug treatment under high-glucose conditions. Ag⁺ (40 μg/mL) plus Met (3.2% or 6.4%) showed enhanced antibacterial activities against both planktonic E. faecalis and biofilm on dentin slices, with low cytotoxicity.

Conclusions

Met enhanced the bactericidal effects of Ag⁺ against both planktonic and biofilm E. faecalis under normal or high-glucose conditions with low cytotoxicity. Further molecular studies are needed to be conducted to understand the mechanisms underlying the synergistic activity between Met and Ag⁺.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12866-021-02291-2.

Periodontitis and Systemic Disorder-An Overview of Relation and Novel Treatment Modalities

Periodontitis, a major oral disease, affects a vast majority of the population but has been often ignored without realizing its long-fetched effects on overall human health. A realization in recent years of its association with severe diseases such as carditis, low birth weight babies, and preeclampsia has instigated dedicated research in this area. In the arena of periodontal medicines, the studies of past decades suggest a link between human periodontal afflictions and certain systemic disorders such as cardiovascular diseases, diabetes mellitus, respiratory disorders, preterm birth, autoimmune disorders, and cancer. Although, the disease appears as a locoregional infection, the periodontal pathogens, in addition their metabolic products and systemic mediators, receive access to the bloodstream, thereby contributing to the development of systemic disorders. Mechanism-based insights into the disease pathogenesis and association are highly relevant and shall be useful in avoiding any systemic complications. This review presents an update of the mechanisms and relationships between chronic periodontal infection and systemic disorders. Attention is also given to highlighting the incidence in support of this relationship. In addition, an attempt is made to propose the various periodonto-therapeutic tools to apprise the readers about the availability of appropriate treatment for the disease at the earliest stage without allowing it to progress and cause systemic adverse effects.

Association between cardiovascular diseases and apical periodontitis: an umbrella review

BACKGROUND

The existence of an association between cardiovascular diseases (CVDs) and apical periodontitis (AP) remains unclear because results obtained from previous clinical studies and reviews are inconsistent or inconclusive.

OBJECTIVE

To conduct an umbrella review to determine whether there is an association between CVDs and the prevalence of AP in adults.

METHODS

The protocol of the review was registered in the PROSPERO database (CRD42020185753). The literature search was conducted using the following electronic databases: Clarivate Analytics' Web of Science Scopus, PubMed and Cochrane Database of Systematic Reviews, from inception to May, 2020, with no language restrictions. Systematic reviews with or without meta-analysis that evaluated the association between CVDs and AP were included. Other types of studies, including narrative reviews, were excluded. Two reviewers independently performed a literature search, data extraction and quality assessment of included studies. Any disagreements or doubts were resolved by a third reviewer. The quality of the reviews was assessed using the AMSTAR 2 tool (A measurement tool to assess systematic reviews), with 16 items. A final categorization of the systematic reviews classified each as of 'high', 'moderate', 'low' or 'critically low' quality.

RESULTS

Four systematic reviews were included in the current review. Three reviews were graded by AMSTAR 2 as 'moderate' quality, whereas one review was graded as 'critically low' quality.

DISCUSSION

Only one systematic review included a meta-analysis. Substantial heterogeneity amongst the primary studies included within each systematic review was notable in preventing a pooled analysis.

CONCLUSIONS

From the limited 'moderate' to 'critically low' quality evidence available, the current umbrella review concluded that a weak association exists between CVDs and AP. In the future, well-designed, longitudinal clinical studies with long-term follow-up are required.