People with a significant burden of periodontal bacteria are more than three times as likely to have hypertension as those with low levels of such bacteria, according to a large international study (Journal of Hypertension, May 5, 2010).
Seven investigators from Columbia University, the University of Miami, the University of Minnesota, and the French School of Public Health collected 4,533 subgingival plaque samples from 653 patients enrolled in the Oral Infections and Vascular Disease Epidemiology Study (INVEST). They analyzed the samples for the presence of 11 different species of periodontal bacteria, including Actinomyces naeslundii and Prevotella intermedia.
The researchers, led by Moise Desvarieux, M.D., Ph.D., found that the odds ratio for prevalent hypertension was 3.05 among the patients in the highest tertile of bacterial burden compared to those in the lowest tertile.
However, another expert in the field believes that while the study's goals are laudable, the investigators included too many parameters to be able to control for all the associated confounding factors.
"It's a good study; it's a study that needed to be done. But I'm just wondering if they could have broken this down into three or four different papers, and looked at the data more closely," said Harvey Wigdor, D.D.S., M.S., a clinical professor in the department of oral medicine and diagnostic sciences at the University of Illinois at Chicago College of Dentistry.
Direct assessments of bacterial burden
Dr. Desvarieux and his colleagues sought to conduct the first investigation of the relationship between periodontal bacteria and prevalent hypertension that incorporated direct assessments of periodontal bacterial burden rather than surrogates of past infection, such as tooth loss. They analyzed plaque samples from INVEST participants in northern Manhattan with periodontal disease, which they defined as a probing depth of 3 or more.
The researchers attempted to control for ethnic background, smoking status, physical activity level, presence of diabetes, body mass index, white blood cell count and concentrations of total serum cholesterol, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, and high-sensitivity C-reactive protein (hs-CRP).
The team found that, after adjusting for conventional risk factors, the mean systolic blood pressure increased significantly with increasing cumulative bacterial burden, at 136, 138, and 143 mmHg for the first, second, and third tertile, respectively (p = 0.0004). The diastolic blood pressure also increased significantly, at 77, 79, and 81 mmHg, respectively.
Furthermore, the prevalence of hypertension was 57%, 62%, and 68%, respectively. This translated into more than threefold higher odds of hypertension between the third and first tertiles; after further adjustment for white blood cell count and titer of hs-CRP, this rose to 3.93. The increase between the first and third tertiles in both hypertension and diastolic blood pressure was more than twice as large for men as for women, while the increase in systolic blood pressure was nearly three times as large in men.
"Our data provide evidence of a direct relationship between the levels of subgingival periodontal bacteria and both SBP [systolic blood pressure] and DBP [diastolic blood pressure], as well as hypertension prevalence," the researchers concluded.
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