Participants who reported having severe periodontal disease reported approximately 40% more chronic conditions than participants who reported having no periodontal disease. To our knowledge, this study is the first to estimate the increased risk of overall chronic illness associated with periodontal disease. The fact that periodontal disease, as a risk factor, is not specific to a single disease but appears to be associated with varied chronic conditions is consistent with the concept that it may contribute to inflammation and damage to various systems. Other persistent, chronic, or recurrent infections may also play a role, as may the total burden of infection.
Our results are similar to a study of NHANES participants (11
), which found associations between need for periodontal treatment and self-reported arthritis, diabetes, a liver condition, and having had a stroke. However, our ability to identify associations of periodontal disease with specific conditions was limited by small numbers. We did not find the expected association between periodontal disease and CHD; based on 3 meta-analyses including many thousands of participants (1
), this association may be in the range of a 15% to 30% increase in risk, and our study did not have the power to detect an association of this size. Small numbers may also have reduced our ability to identify a link between severe periodontal disease and diabetes, a comparison which achieved significance in our study before, but not after, covariates were added to the model.
Major factors potentially limiting the validity of this research are the low response rate and the use of self-reported measures of periodontal disease and chronic disease. Although some large-scale studies, notably NHANES (15
), have included periodontal clinical examinations, the expense of conducting clinical exams has led to efforts to develop and use self-reported measures for surveillance and research. A Centers for Disease Control and Prevention and American Academy of Periodontology workgroup concluded that multivariable modeling of self-reported measures is promising for predicting the population prevalence of periodontitis (23
). The specific measure used in this report has not been validated by clinical measures such as pocket depth but combines questions that have been identified as having good validity (24
) or as contributing to multivariable models (25
). More research is needed to validate the specific approach used in this research and to determine the optimal approach (in terms of validity, reliability, and cost effectiveness) to self-reported periodontal disease.
Second, the response rate for this study (CASRO response rate 38%) was low, so we compared characteristics of the WAHS sample with the American Community Survey (ACS, 26
). These characteristics were similar on most measures. Although a small number of characteristics (such as marital status) differed between WAHS and ACS, both number of diagnoses and metabolic syndrome remained significant when these were added as covariates, so these differences do not appear to have affected the major results. Furthermore, several recent reviews indicate that there is no consistent relationship between response rates and the amount of nonresponse bias. The range of response rates in the studies they reviewed was about 25% to 85% (27
The sample was designed to be representative of the Washington State population. However, unless the associations of periodontal disease with chronic disease and metabolic syndrome vary between populations, the results may be generalized to adults in other states.
The range of chronic conditions associated with periodontal disease suggests that interventions to increase periodontal health may have far-reaching effects on public health. A review by Tonetti (4
) found that intensive periodontal therapy resulted in a decrease in systemic inflammation and an improvement of endothelial dysfunction in otherwise healthy subjects. Also, a recent study examining the medical costs of diabetes patients found a cost savings in the range of 3% to 8% for patients who were receiving regular dental care compared with those not receiving any preventive or periodontal services (30
In conclusion, these results provide evidence that people with severe periodontal disease are more likely to have metabolic syndrome and other chronic conditions compared with people without periodontal disease. These associations did not appear to result from confounding from age, sex, income, smoking, or psychosocial stress. Intervention research about the effectiveness of periodontal treatment to prevent or control various chronic diseases, which have in common an inflammatory process, is needed.