Relationship Between Periodontitis and the Severity of Lung Infection Caused by COVID-19: A Case-Control Observational Study

BACKGROUND AND AIMS: The ongoing COVID-19 pandemic necessitates a deeper understanding of risk factors associated with severe outcomes. Chronic Periodontitis, a persistent inflammatory condition affecting the gums, may be linked to increased COVID-19 severity. This study aimed to determine the relationship between periodontitis and the severity of lung infection caused by COVID-19. METHODS: This observational study was conducted at Valiasr Hospital, Zanjan, Iran, between 2019 and 2020. Participants included individuals with COVID-19-related pneumonia (cases) and a control group without COVID-19. Pneumonia severity was assessed using the Pneumonia Severity Index, while periodontal status was evaluated through clinical parameters such as the Plaque Index, Gingival Index, and probing depth (PD). Statistical analyses included Chi-square, Fisher's exact, Mann-Whitney U tests, and multivariate models to examine associations and control for potential confounders, including age, gender, education, and place of residence. RESULTS: The study included 160 participants, with 86 classified as COVID-19 cases and 74 as controls. Analysis revealed no significant disparities in demographic variables between the two groups. Additionally, no notable differences were observed in the distribution of periodontal conditions. However, a significant correlation emerged between periodontal indices and COVID-19 severity (p < 0.05). Further analysis showed a significant relationship between periodontal conditions and the severity of lung involvement in COVID-19. Logistic regression analysis identified PD as the only significant predictor of COVID-19 severity, with an odds ratio of 1.083 (95% CI: 1.002-1.171, p = 0.04), indicating an 8.3% increase in the odds of severe COVID-19 per unit increase in PD. Additionally, multinomial logistic regression highlighted associations between PD, extent of involvement, and disease type with the severity of COVID-19 pulmonary involvement, reinforcing their potential as predictive factors. CONCLUSION: Further research is warranted to validate these observations, elucidate the underlying mechanisms, and explore potential interventions targeting periodontal health as a strategy for COVID-19 risk reduction.