Abstract
ObjectiveThe association between periodontitis and glycaemic control is complex, and often described as 'bidirectional'. Although epidemiological studies have examined this relationship extensively, a disagreement on periodontitis case definition still exists. This study aimed to assess the influence of case definition on the association between periodontal disease and glycaemic status. MethodsThe study is a secondary analysis of data from the United States National Health and Nutrition Examination Survey (NHANES), 2009-2014 cycles. The association between periodontitis and glycated haemoglobin (HbA1c) was assessed using different periodontitis case definitions: the definition by the Centers for Disease Control and Prevention and the American Academy of Periodontology (CDC/AAP), Community Periodontal Index (CPI), >= 1 site with >= 3 mm clinical attachment loss (CAL) and >= 4 mm probing depth (PD), >= 1 site with >= 4 mm CAL and >= 4 mm PD, the 5th European Workshop definitions, Machtei et al. 'established periodontitis', the 2017 World Workshop classification, and self-reported periodontitis. The associations between periodontitis and HbA1c were compared across the case definitions. ResultsThere was substantial variability in prevalence estimates of periodontitis, and in the strength of association between periodontitis and HbA1c when different case definitions were applied. The CDC/AAP and stage III/IV periodontitis were consistently significantly associated with elevated HbA1c. For stage III/IV, the adjusted odds ratios of prediabetes and diabetes HbA1c were 1.19 and 1.76, respectively. ConclusionComprehensive periodontitis case definitions that account for CAL and PD, such as the CDC/AAP and the 2017 classification, seem to better detect the association between periodontal disease and HbA1c.