Poor oral health and risk of incident myocardial infarction: A prospective cohort study of Swedish adults, 1973–2012

Scientific Reports, Jul 2018

Previous studies provide conflicting evidence as to whether there is an association between poor oral health and an increased risk of myocardial infarction. The aim of the study was to deepen knowledge of the association between oral health and myocardial infarction risk using a large (n = 20,133), prospective, and population-based cohort in Uppsala, Sweden. Oral health was determined during a clinical dental examination at entry into the cohort in 1973/74. Individuals were followed through linkage with the Swedish National Patient Register, Cause of Death Register and Emigration Register. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) for total, non-fatal and fatal myocardial infarction events. Increased risks of total, non-fatal and fatal myocardial infarction events among individuals with fewer reference teeth at examination, more dental plaque and a borderline significant increased risk among individuals with oral lesions were observed. Adjustment for multiple potential confounding factors did not change the results appreciably. However, the observed HRs generally decreased towards one when the analysis was confined to non-tobacco users only. The results from this study indicate that poor oral health is associated with a slightly increased risk of myocardial infarction; however, these results may be partly explained by residual confounding.

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Poor oral health and risk of incident myocardial infarction: A prospective cohort study of Swedish adults, 1973–2012

Abstract Previous studies provide conflicting evidence as to whether there is an association between poor oral health and an increased risk of myocardial infarction. The aim of the study was to deepen knowledge of the association between oral health and myocardial infarction risk using a large (n = 20,133), prospective, and population-based cohort in Uppsala, Sweden. Oral health was determined during a clinical dental examination at entry into the cohort in 1973/74. Individuals were followed through linkage with the Swedish National Patient Register, Cause of Death Register and Emigration Register. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) for total, non-fatal and fatal myocardial infarction events. Increased risks of total, non-fatal and fatal myocardial infarction events among individuals with fewer reference teeth at examination, more dental plaque and a borderline significant increased risk among individuals with oral lesions were observed. Adjustment for multiple potential confounding factors did not change the results appreciably. However, the observed HRs generally decreased towards one when the analysis was confined to non-tobacco users only. The results from this study indicate that poor oral health is associated with a slightly increased risk of myocardial infarction; however, these results may be partly explained by residual confounding. Introduction Cardiovascular disease (CVD) is one of the leading causes of death and morbidity globally, with an estimated 17.5 million deaths due to CVD in 20121 and 295 million disability-adjusted life years (DALYs) in 20102. There are many identified risk factors for CVD including tobacco smoking3, high alcohol consumption4, sedentary lifestyle5, high blood pressure6 and genetic predisposition7. Since the 1990s, poor oral health has also been identified as a potential risk factor for CVD8. Poor oral health is considered generally to be one of the most prevalent diseases globally, with 32% of individuals worldwide aged 65 years or older estimated to be edentulous (having no natural teeth)9. Furthermore, a study in the United States observed a 28% prevalence of oral mucosal lesions in a nationally representative sample of individuals10. Previous studies have observed an increased risk of myocardial infarction (MI) with various measures of oral health including tooth loss11, periodontal diseases12, and dental plaque13. In contrast, others have observed null association and suggested that the reported associations are a result of uncontrolled confounding14,15,16. Thus, there is still debate regarding the association between oral health and MI, and whether any association is causal. To investigate the association between oral health and the risk of MI events, we examined the hazards of total, non-fatal and fatal incident MI events in relation to the number of teeth, presence of dental plaque and presence of oral lesions in a large, prospective, and population-based cohort in Uppsala, Sweden. Materials and Methods Study population All individuals aged 15 years or older during the year of examination and registered in the National Civil Register as living in the municipalities of Enköping or Håbo, in Uppsala County in Sweden were invited to take part in the study (n = 30,118). After two rounds of recruitment, a total of 20,333 individuals received a clinical dental examination in 1973/74, resulting in a response rate of 68 percent (Fig. 1). The original selection of participants and data collection was for the purpose of studying the prevalence of oral mucosal lesions in Sweden17. Individuals were excluded if they had a MI event prior to entry into the cohort (n = 79). Entry into the cohort was set to the 15th day of the month of dental examination as only a record of the month and year was available. Ethical approval has been granted by the ethics committee of the Medical Faculty at Uppsala Universitet (DNR: 82/93) and the Regional Ethics Vetting Board in Stockholm, Sweden (DNR: 2014/671–31/4). Informed consent was obtained from all participants. All methods were performed in accordance with the relevant guidelines and regulations. Figure 1 Flow diagram for participant recruitment into the cohort in 1973/74. *Reasons for non-participation in first round of recruitment (sample of non-participants, n = 2,382): Recently participated in another health examination (n = 371), work (n = 328), temporarily away (n = 281), no contact (n = 321), change of residence (n = 224), illness at home (n = 152), no remembrance of reason (n = 149), refusal (n = 149), hospitalised (n = 115), did not receive parcel (n = 64), forgot to come (n = 48), old age (n = 35), recently dead (n = 28), long distance to examination local (n = 24), fear of physicians and/or dentists (n = 20), dislike of mass investigations (n = 18), pregnancy (n = 10), other reasons (n = 45). †Reasons for non-participation in second round of recruitment: Change (...truncated)


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Katherine Wilson, Zhiwei Liu, Jiaqi Huang, Ann Roosaar, Tony Axéll, Weimin Ye. Poor oral health and risk of incident myocardial infarction: A prospective cohort study of Swedish adults, 1973–2012, Scientific Reports, 2018, Issue: 8, DOI: 10.1038/s41598-018-29697-9