Background
Periodontitis is a chronic and long-lasting low-grade inflammatory disease that leads to a break-down of the connective tissue and bone that anchors the teeth to the jaws [
1,
2]. It is a highly prevalent disease worldwide contributing to the global burden of chronic diseases and represents a major public health problem in many countries [
3,
4]. In Korea, the prevalence of periodontitis is 29.4% among adults [
5]. Periodontitis is also related to systemic alterations such as atherosclerotic vascular disease and metabolic syndrome [
6,
7].
Long-term and excessive alcohol consumption can influence host defenses causing toxic damage, which is implicated in a wide variety of diseases, disorders, and injuries such as oro-pharyngeal cancer, liver cirrhosis, pancreatitis, hypertension, gastritis, diabetes, some forms of stroke, and mental disorders such as depression [
8‐
10].
As chronic and even acute, moderate alcohol use can increase host susceptibility to infections caused by bacterial pathogens and impaired host defense after alcohol exposure appears to be linked to a combination of decreased inflammatory response, altered cytokine production, and abnormal reactive oxygen intermediate generation [
11], it may be related to periodontitis independently of other potential confounders.
However, a recent systematic review reported that, among 14 studies, only 3 studies showed clear association, and 6 studies showed marginal or weak association of alcohol consumption or dependence with periodontitis, while the other 5 studies did not find significant association [
10]. Moreover, there was much diversity in the way of measuring alcohol consumption, and most studies considered limited potential confounders or examined non-representative small samples [
10,
12,
13]. Hence, further studies are needed to elucidate whether or not alcohol consumption is a risk factor for periodontitis.
The Alcohol use disorders identification test (AUDIT) was developed by the World Health Organization (WHO) and validated by lots of studies as a simple method of screening for excessive drinking as the cause of the presenting illness, which is the only screening test specifically designed for international use, and in comparison to other screening tests, the AUDIT has been found to perform equally well or at a higher degree of accuracy across a wide variety of criterion measures [
14].
When investigating the periodontitis-associated factors, effect modification needs to be considered in an appropriate manner in epidemiological studies because multivariate models with a single estimate require homogeneity of the effect across different levels of extraneous variables such as gender and smoking [
15].
However, there are few studies on the association between alcohol consumption based on AUDIT score and periodontitis in a nationally representative sample considering effect modification.
Therefore, the aim of this study is to assess the association of harmful alcohol use based on AUDIT score with periodontal status according to gender and smoking in a representative sample of Korean adults.
Discussion
In this study, an association was found between harmful alcohol use and periodontal status after adjusting for the socio-demographic variables, oral and general health behaviors, and oral health status, especially in men and non-smokers.
While alcohol consumption has been widely perceived as a risk factor of periodontitis due to the biological plausibility based on the relationship between alcohol use and impaired systemic conditions such as reduced resistance to infection and liver damage [
19‐
21], several studies reported a negative correlation between alcohol consumption and periodontitis based on longitudinal and cross-sectional researches.
For example, Jansson [
22] conducted a longitudinal investigation of 513 individuals from the County of Stockholm in 1970 and 1990. He did not find any significant association between alcohol consumption and periodontitis. Even though the subjects with higher alcohol consumption had calculus more frequently than those with lower alcohol consumption, alcohol consumption was not associated with periodontitis. Torrungruang et al. [
23] performed a cross-sectional survey targeting 2,005 people aged 50 to 73 years in Thailand, and also reported that alcohol consumption had no significant effect on the severity of periodontal disease severity in the multivariate model.
This disparity might be due to differences in the potential confounders, assessment of alcohol consumption, criteria of periodontitis, and ethnical backgrounds. In addition, effect modification could be another reason for the variation. Most previous studies on the association between alcohol consumption and periodontitis did not consider effect modifiers. Ylöstalo et al. [
15] reported that effect modification was not always treated in an appropriate manner in epidemiological studies although it was a basic concept in quantitative research. Based on the analysis of simulation data, they concluded that effect modification might explain the variation in the results of studies on the association between periodontitis and systemic disease. In this study, as we found significant interaction terms, subgroup analysis was performed with subgroups stratified by the levels of effect modifiers. The results of this study did not support the association between harmful alcohol use and periodontal status in the total sample. However, subgroup analysis showed that harmful alcohol use was significantly associated with higher CPI in men and non-smokers.
To the best of our knowledge, this is the first study to report gender and smoking as effect modifying factors of the association between alcohol consumption and periodontal status. Some studies reported that smoking and alcohol consumption are associated with increased risk of systemic diseases such as fatty liver disease and metabolic syndrome, especially when these two exposures occur together [
24,
25]. The result of this study is opposite to those previous results. However, considering that smoking is one of the strongest risk factors for periodontitis [
26], it could be inferred that smoking may mask the effect of alcohol consumption on periodontal health in smokers.
Briasoulis et al. [
27] found that the association between light to moderate alcohol intake and the risk of developing hypertension differed between women and men. They explained that differences in the pattern of drinking, beverage choices, and smoking habits may contribute to the observed sex differences because the health effects of drinking may depend on drinking pattern, and failure to differentiate episodic from regular drinkers may obscure the real associations. It is consistent with the gender difference found in this study.
Further studies will be needed to elucidate the association between alcohol consumption and periodontal status according to gender and smoking.
The difference in the assessment of alcohol consumption is also suggested to be one of the explanations for the variation in the results of the studies on the association between alcohol consumption and periodontal status. Amaral Cda et al. [
10] reported that alcohol consumption was assessed by various unvalidated questionnaires with different criteria varied according to researchers in lots of studies. Therefore, this study used the AUDIT to determine harmful alcohol use.
The AUDIT was developed by the WHO and validated by lots of studies as a screening tool for excessive drinking [
14]. Epidemiologic studies have used the AUDIT [
28,
29]. In order to evaluate the AUDIT against other common screening measures, Allen et al. [
30] reviewed the studies in which the sensitivity and specificity of the AUDIT were contrasted with those of the alternative measures. They found that the AUDIT performed at a level at least comparable with and generally exceeding that of the alternate measures. However, there have been few studies on the association between periodontitis and alcohol consumption based on AUDIT [
31].
This study had several limitations. The periodontal status was assessed by CPI. Although CPI is an easier way to assess the prevalence of periodontitis in a population survey and has been adopted as an index for periodontitis in epidemiologic studies on the association between systemic health and periodontal disease [
32], the limitation of CPI should be deliberately considered since it can overestimate or underestimate the prevalence of periodontitis due to the use of representative teeth and pseudo pockets [
33]. Therefore, the term of higher CPI was used instead of periodontitis to classify periodontal status. Another important limitation of this study is its cross-sectional design, which makes it impossible to determine the direction of the causal relationship of harmful alcohol use with periodontal status. As the association of subgroups found in this study was so weak, further studies will be needed to confirm the association between harmful alcohol use and periodontal status in men and non-smokers.
Nevertheless, this is the first epidemiologic study to report an effect modification of the association between harmful alcohol use and periodontal status by gender and smoking in a nationally representative sample of adults.
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Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
BK designed the study and, YH and HH performed the statistical analysis. KH, SJ, and SH interpreted the findings and drafted the manuscript. BK read and approved the final manuscript. All Authors read and approve the final manuscript.