Periodontal disease does not increase the risk of subsequent psoriasis

www.nature.com/scientificreports OPEN Periodontal disease does not increase the risk of subsequent psoriasis Yoo Sang Baek 1, Eun‑Jung Kwak 2, Young Chan Kim 1, Ko Eun Kim 1, Hae Jun Song 1 & Jiehyun Jeon 1* Previous studies suggested that chronic periodontitis may be a risk factor for psoriasis. However, no study has confirmed this relationship for all stages of periodontal disease (gingivitis and periodontitis). This nationwide population-based retrospective cohort study aimed to investigate whether periodontal disease is an independent risk factor for the development of subsequent psoriasis. Patients aged ≥ 20 years who underwent both medical and oral checkups from the National Health Screening Program between 2002 and 2007 were selected from a customized database provided by the National Health Insurance Service (NHIS). Then, patients with periodontal disease (n = 3,682,468) and without periodontal disease (control, n = 3,637,128) according to oral examination results were identified. We tracked each patient for subsequent psoriasis diagnosis until the end of 2018 using NHIS database. The incidence rates of psoriasis per 1000 person-years were 0.36 and 0.34 in the periodontal disease group and control groups, respectively. After adjusting for potential cofactors, no significant increase in risk (adjusted hazard ratio, 0.994; 95% confidence interval, 0.974–1.015) was observed. Similar results were observed when analyzing the risk of psoriasis in patients who required scaling or periodontal surgery. In conclusion, periodontal disease is not an independent risk factor of psoriasis. Psoriasis is an immune-mediated chronic inflammatory skin disease associated with a substantial physical and psychological burden1. Its global prevalence ranges from 0.2 to 4.8%2. Psoriasis is known to be associated with multiple comorbidities, such as psoriatic arthritis, cardiovascular disease, metabolic syndrome (obesity, diabetes, hypertension, and dyslipidemia), and psychiatric d isorders1. Periodontal disease is a group of inflammatory conditions that affect the gingiva, bone, and periodontal ligaments that provide structural support to the teeth3,4. Periodontal disease usually starts with gingivitis, which is a mild, reversible, and localized inflammation of the gum that is initiated by a microbial biofilm (dental plaque)3,4. The condition progresses to periodontitis when the inflammation extends deeper and causes the loss of supporting tissue, which creates periodontal p ockets3,4. The prevalence of periodontal disease varies based on the 3–5 disease definition and study population . A surveillance study in the United States showed that 47.2% of adults aged ≥ 30 years suffer from some form of periodontitis6. Currently, investigators believe that periodontal diseases (gingivitis and periodontitis) share common etiopathogenesis, and gingivitis almost always precedes periodontitis3,4. In addition, the absence of gingivitis is a good indicator of long-term periodontal health in an individual3,7. Furthermore, periodontal disease is not limited to the oral space but is an inflammatory condition associated with systemic diseases such as diabetes and cardiovascular diseases3,4. Numerous studies have reported association between periodontal disease (mainly, chronic periodontitis) and p soriasis8–11. Shared genetic factors, common pathophysiology, and risk factors have been suggested to explain this a ssociation11,12. For instance, increase level of interleukin (IL)-17 has been implicated in common pathophysiological link between two entities12. Elevated levels of IL-17 in psoriatic patients systemically inhibits osteoblast and induces osteoclast activities, resulting in low bone formation and bone loss13,14. This process may theoretically contribute to the development of p eriodontitis13. On the other hand, Porphyromonas gingivalis in chronic periodontitis can activate the Th17 pathway, and the levels of locally produced IL-17 increased in periodontitis patients13,15,16. Therefore, increased level of IL-17 in psoriasis and periodontitis may generate a vicious c ycle12. Moreover, recent studies have shown that periodontal disease may be an independent risk factor for psoriasis17–19. However, this suggestion can be confounded by common risk factors (such as smoking, diabetes, 1 Department of Dermatology, Guro Hospital, Korea University College of Medicine, 148 Gurodong‑ro, Guro‑gu, Seoul 08308, Republic of Korea. 2National Dental Care Center for Person with Special Needs, Seoul National University Dental Hospital, Seoul, Republic of Korea. *email: Scientific Reports | (2023) 13:5942 | https://doi.org/10.1038/s41598-023-32907-8 1 Vol.:(0123456789) www.nature.com/scientificreports/ and obesity) of both disease. A recent study in Korea investigated the risk of psoriasis in patients with periodontal disease who had been diagnosed with chronic periodontitis and visited dental c linics17. Since patients with early periodontal disease as well as chronic periodontitis rarely seek professional dental care3,4, this recent study may have selected patients with advanced stages who sought clinical care. Therefore, there is a lack of evidence for relationship between psoriasis and general periodontal disease (including gingivitis and periodontitis), regardless of dental visit status. We hypothesized that overall periodontal disease is an independent risk factor for subsequent psoriasis. To capture early or asymptomatic periodontal disease patients, we used oral examination results from the National Health Screening Program (NHSP) for the detection of periodontal disease. Materials and methods Data source and study population. We conducted a nationwide population-based retrospective cohort study using a customized database provided by the National Health Insurance Service (NHIS). The NHIS is a single non-profit insurer in Korea that covers insurance for almost the entire Korean population. It also offers standardized biennial medical and oral checkups under the NHSP. The NHIS manages a computerized database with healthcare-related information about individuals as well as their personal information. The NHIS provides a customized database to researchers with de-identified information regarding the study population upon request. In order to acquire as many individuals as possible, we requested a customized database of all patients aged ≥ 20 years who underwent both medical and oral checkups on the same day (the index date) from 2002 and 2007. In the customized database, we collected medical and oral checkup results, personal information (sex, birth year, and death year), as well as medical claims data of the participants from the index date to the end of 2018. The medical diagnoses in the claims data were defined using the International Classification of Disease, 10th Revision (ICD-10) codes, which is an internationally-recognized classification system that provides standardized codes for eac (...truncated)