Periodontitis case definition affects the association with renal function in kidney transplant recipients

Aim: The aim of this analysis was to investigate the association between periodontal status and renal allograft function in a cohort of renal transplant patients using different periodontitis case definitions. Material and methods: Fifty-eight kidney transplant patients were included. The subjects were classified into two groups, deterioration or stable/improvement of renal allograft function as expressed by the difference in glomerular filtration rate (GFR) between two time points at least 6 months apart. Chronic periodontitis was defined as: (1) two or more interproximal sites with clinical attachment level (CAL) >= 4 mm or two or more interproximal sites with probing depth (PD) >= 5 mm (DEF1); (2) PD >= 5 or CAL >= 4 in at least six proximal sites (DEF2); and (3) PD >= 5 or CAL >= 4 in at least two proximal sites in each quadrant (DEF3). Results: In a multivariate linear regression model, none of the continuous periodontal variables were significantly associated with deterioration of allograft function. Of the three definitions of chronic periodontitis, only DEF2 emerged as significantly more prevalent in subjects with GFR deterioration and was a statistically significant predictor of GFR deterioration over time. Conclusion: These findings underscore the importance of periodontitis 'case definition' in the observed statistical associations between periodontitis and systemic disease.