Association Between Dementia Development and COVID-19 among Individuals Who Tested Negative for COVID-19 in South Korea: A Nationwide Cohort Study.

We aim to assess whether the number of newly diagnosed dementia increases and whether comorbid psychiatric symptoms of patients with dementia worsen, in people who were tested for COVID-19. We used electronic medical records from a nationwide cohort consisting of people who tested positive (positive group), tested negative (negative group), and those who did not receive the test (control group) for COVID-19. For people with neither a history of dementia nor mild cognitive disorder (MCI), the negative group was more likely to develop dementia than the control group, and less likely to develop MCI than the positive group. For people who already had dementia, the negative group was more likely to develop comorbid psychiatric disorders than the control group, but less likely than the positive group. These findings suggest the necessity of managing mental health not only for patients with COVID-19 but also for people who tested negative for COVID-19.

Incidence of Diabetes After Cancer Development: A Korean National Cohort Study.

Importance: Diabetes is an established risk factor for developing cancer. A limited body of evidence also suggests that cancer can increase the risk of developing new cases of diabetes, but the evidence is inconclusive. Objective: To evaluate whether the development of cancer is associated with increasing risk of subsequent diabetes. Design, Setting, and Participants: This cohort study included a nationally representative sample of the Korean general population observed for up to 10 years (January 1, 2003, to December 31, 2013). A total of 524 089 men and women 20 to 70 years of age without diabetes and with no history of cancer at baseline were included. Exposures: Incident cancer (time-varying exposure). Main Outcomes and Measures: Incident type 2 diabetes using insurance claim codes. Results: During 3 492 935.6 person-years of follow-up (median follow-up, 7.0 years) in 494 189 individuals (50.0% female; mean [SD] age, 41.8 [12.5] years), 15 130 participants developed cancer and 26 610 participants developed diabetes. After adjustment for age, sex, precancer diabetes risk factors, metabolic factors, and comorbidities, the hazard ratio (HR) for diabetes associated with cancer development was 1.35 (95% CI, 1.26-1.45; P < .001). The excess risk for diabetes was highest in the first 2 years after cancer diagnosis, but it remained elevated throughout follow-up. By cancer type, development of pancreatic (HR, 5.15; 95% CI, 3.32-7.99), kidney (HR, 2.06; 95% CI, 1.34-3.16), liver (HR, 1.95; 95% CI, 1.50-2.54), gallbladder (HR, 1.79; 95% CI, 1.08-2.98), lung (HR, 1.74; 95% CI, 1.34-2.24), blood (HR, 1.61; 95% CI, 1.07-2.43), breast (HR, 1.60; 95% CI, 1.27-2.01), stomach (HR, 1.35; 95% CI, 1.16-1.58), and thyroid cancer (HR, 1.33; 95% CI, 1.12-1.59) was associated with a significantly increased risk of diabetes. Conclusions and Relevance: In this large Korean cohort, cancer development increased the risk of subsequent diabetes. These data provide evidence that cancer is associated with an increased risk of diabetes in cancer survivors independent of traditional diabetes risk factors. Physicians should remember that patients with cancer develop other clinical problems, such as diabetes, with higher frequency than individuals without cancer, and should consider routine diabetes screening in these patients.