Differences in health care expenditure due to the comorbidity status of periodontal disease and diabetes mellitus

Background: To investigate the differences in health care expenditure (HCE) due to the comorbidity status of periodontal disease (PD) and diabetes mellitus (DM). Methods: This cohort study used health care claims and oral health screening data to identify participants with PD or DM and followed them for 1 year to assess their HCE. PD and DM were determined based on PD screening and medical claims data, respectively. The study participants were divided into four groups: participants without PD and DM (PD−/DM−), participants with PD and without DM (PD+/DM−), participants without PD and with DM (PD−/DM+), and participants with PD and DM (PD+/DM+). Covariates included age, sex, smoking status, and Charlson Comorbidity Index (CCI) score. A generalized linear model (GLM) with a gamma distribution and log link function was used to examine the association between comorbidity and annual HCE, and a two-part model was used to assess the differences in annual HCE. Results: In total, 790 participants (mean age: 63.1, 30.3% male) were included. Compared with the PD−/DM− group, the relative cost ratio (RCR) for the PD+/DM+, PD−/DM+, PD+/DM− groups were 1.31 (95% confidence interval [CI]: 1.06–1.62), 1.27 (95% CI: 0.99–1.64), 1.01 (95% CI: 0.89–1.14) times higher, respectively. The adjusted mean annual HCE for the PD+/DM+, PD−/DM+, PD+/DM− groups were ¥59,328 (95% CI: 14,171–104,484), ¥50,228 (95% CI: −15,801–116,256), ¥-2,162 (95% CI: −24,598–20,274) higher than the PD−/DM− group, respectively. Conclusion: This study provides a significant contribution of PD to the increase in HCE, particularly in individuals with DM. Plain Language Summary: The association between periodontal disease (PD) and diabetes mellitus (DM) has commonly been described in previous literature, but the health expenditure incurred when PD and DM coexist is not clear. This study investigates the differences in health care expenditure (HCE) due to the comorbidity status of PD and DM. HCE is calculated from medical, dental, and pharmacy-dispensing expenditures from the claims data. PD was defined by periodontal pocket scores, and DM was determined based on medical records. Study participants were divided into four groups based on whether they had PD, DM, both, or neither. The results showed that people with both PD and DM had higher HCE compared with those without PD and DM. These findings may suggest the importance of cooperation between medical and dental professionals in the treatment of DM in terms of HCE.