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Science in the News

PAROKRANK: A Study of Periodontitis and Its Relation to Coronary Artery Disease

January 26, 2016 According to a 2012 Scientific Statement from the American Heart Association,1 “A link between oral health and cardiovascular disease has been proposed for more than a century.”  The latest publication to explore this link comes from Karolinska University Hospital in Sweden and is known as “PAROKRANK” (“Periodontitis and its relation to coronary artery disease”).2  Although PAROKRANK found a 28% increased risk of first myocardial infarction (MI) in patients with periodontitis after controlling for variables such as diabetes and smoking, the observational nature of the study design cannot establish a direct cause and effect, only an association between the two conditions.

PAROKRANK was a multicenter, case-control study that enrolled 805 patients (<75 years) who presented with a first MI at one of 17 Swedish hospitals between 2010 and 2014.  The enrolled patients were matched with 805 control individuals without MI who were randomly selected from a national population registry; patients and controls were matched for postal code, sex, and age (+/- 3 months).  Patients were recruited during the hospital stay and scheduled for outpatient visits 6 to 10 weeks later at the local departments of cardiology and dental medicine.  Both the patients and controls underwent comprehensive cardiologic evaluations, including fasting blood work, physical examination, heart rate and blood pressure measurement, body weight, and waist circumference measurement.  Dental examinations were performed according to a standardized protocol and included panoramic radiographs to determine alveolar bone height.  Periodontal status was classified as healthy (>80% remaining bone), mild to moderate (79% to 66% remaining bone), or severe periodontal disease (<66% remaining bone).  Investigators collected information on approximately 100 variables that could be considered possible confounders.

Periodontal disease was present in 43% of the patient cohort compared with 33% of controls (p<0.001) and there was an increased risk for MI among patients with periodontal disease (odds ratio [OR] 1.49; 95% confidence interval [CI]: 1.21-1.83), which remained significant (OR 1.28; 95% CI: 1.03-1.60) after adjusting for variables that differed between patients and controls (e.g., smoking habits, diabetes, years of education, and marital status).  Although the authors state that “these findings strengthen the possibility of an independent association between [periodontal disease] and MI,” they also acknowledge that “The major limitation is that PAROKRANK is an observational study, which can support but not prove the concept of a causal relationship.”

In a related editorial,3 Stewart and West echo that PAROKRANK “adds to the strong evidence for an association between periodontitis and myocardial infarction, but does not prove causation.”


  1. Lockhart PB, Bolger AF, Papapanou PN, et al. Periodontal disease and atherosclerotic vascular disease: does the evidence support an independent association?: a scientific statement from the American Heart Association. Circulation 2012;125(20):2520-44.
  2. Ryden L, Buhlin K, Ekstrand E, et al. Periodontitis Increases the Risk of a First Myocardial Infarction: A Report From the PAROKRANK Study. Circulation 2016.
  3. Stewart R, West M. Increasing Evidence for an Association Between Periodontitis and Cardiovascular Disease. Circulation 2016.
Prepared by: Center for Scientific Information, ADA Science Institute

About Science in the News

Science in the News is a service by the American Dental Association (ADA) to its members to present current information about science topics in the news. The ADA is a professional association of dentists committed to the public's oral health, ethics, science and professional advancement; leading a unified profession through initiatives in advocacy, education, research and the development of standards. As a science-based organization, the ADA's evaluation of the scientific evidence may change as more information becomes available. Your thoughts would be greatly appreciated.

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