The influence of periodontitis case definition on the association between periodontal disease and glycaemic status.

Objective: The 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.

Methods: The 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.

Results: There 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.

Conclusion: Comprehensive 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.