Background: There is inconclusive and controversial evidence of the association between allergic diseases and the risk of adverse clinical outcomes of coronavirus disease 2019 (COVID-19). Objective: We sought to determine the association of allergic disorders with the likelihood of a positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) test result and with clinical outcomes of COVID-19 (admission to intensive care unit, administration of invasive ventilation, and death). Methods: A propensity-score-matched nationwide cohort study was performed in South Korea. Data obtained from the Health Insurance Review & Assessment Service of Korea from all adult patients (age, >20 years) who were tested for SARS-CoV-2 in South Korea between January 1, 2020, and May 15, 2020, were analyzed. The association of SARS-CoV-2 test positivity and allergic diseases in the entire cohort (n 5 219,959) and the difference in clinical outcomes of COVID-19 were evaluated in patients with allergic diseases and SARS-CoV-2 positivity (n 5 7,340). Results: In the entire cohort, patients who underwent SARS-CoV-2 testing were evaluated to ascertain whether asthma and allergic rhinitis were associated with an increased likelihood of SARS-CoV-2 test positivity. After propensity score matching, we found that asthma and allergic rhinitis were associated with worse clinical outcomes of COVID-19 in patients with SARS-CoV-2 test positivity. Patients with nonallergic asthma had a greater risk of SARS-CoV-2 test positivity and worse clinical outcomes of COVID-19 than patients with allergic asthma. Conclusions: In a Korean nationwide cohort, allergic rhinitis and asthma, especially nonallergic asthma, confers a greater risk of susceptibility to SARS-CoV-2 infection and severe clinical outcomes of COVID-19.

ObjectiveThe adverse effects of proton pump inhibitors (PPIs) have been documented for pneumonia; however, there is no consensus regarding whether the use of PPIs might be harmful regarding the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In this regard, we aimed to measure the potential associations of the current use of PPIs with the infection rates of COVID-19 among patients who underwent SARS-CoV-2 testing.DesignData were derived from a Korean nationwide cohort study with propensity score matching. We included 132 316 patients older than 18 years who tested for SARS-CoV-2 between 1 January and 15 May 2020. Endpoints were SARS-CoV-2 positivity (primary) and severe clinical outcomes of COVID-19 (secondary: admission to intensive care unit, administration of invasive ventilation or death).ResultsIn the entire cohort, there were 111 911 non-users, 14 163 current PPI users and 6242 past PPI users. After propensity score matching, the SARS-CoV-2 test positivity rate was not associated with the current or past use of PPIs. Among patients with confirmed COVID-19, the current use of PPIs conferred a 79% greater risk of severe clinical outcomes of COVID-19, while the relationship with the past use of PPIs remained insignificant. Current PPI use starting within the previous 30 days was associated with a 90% increased risk of severe clinical outcomes of COVID-19.ConclusionPatients taking PPIs are at increased risk for severe clinical outcomes of COVID-19 but not susceptible to SARS-CoV-2 infection. This suggests that physicians need to assess benefit–risk assessments in the management of acid-related diseases amid the COVID-19 pandemic.

In medical research, when independent variables are categorical (i.e., dividing groups), statistical analysis is often required. This situation mostly occurs on randomized controlled trials and observational studies that have multiple patient groups. Also, when analyzing continuous independent variables in a single patient group, breakpoints can be set to categorize them into several groups. To test statistical differences between groups, a proper statistical method should be selected, mainly based on the type of dependent variable (i.e., result) and context. The most commonly used tests include t-test, analysis of variance (ANOVA), non-parametric tests, chi-square, and post-hoc analyses. In this article, the author explains statistical methods and which methods should be selected. Through this paper, researchers will be able to understand statistical methods and receive help when choosing and performing statistical analysis. The article can also be used as a reference when researchers justify their statistical approaches when publishing research results.

Background: Major questions remain regarding the agestratified trends of allergic diseases and asthma in Korea.Purpose: To identify the estimated recent prevalence and 10- year trends in asthma, allergic rhinitis, and atopic dermatitis among the Korean population from 2008 to 2017.Methods: This nationwide cross-sectional survey (Korean National Health and Nutrition Examination Survey) over 10 years (2008–2017) examined representative samples of the Korean population (n=85,006) including 2,131 infants, 4,352 preschool children, 12,919 school-age children, 44,200 adults, and 21,404 elderly adults.Results: In the 2016 to 2017 population, the estimated prevalence of asthma was 0.9% in infants, 2.3% in preschool children, 4.1% in school-age children, 2.3% in adults, and 4.1% in the elderly. The estimated prevalence of allergic rhinitis was 9.0%, 20.2%, 27.6%, 17.1%, and 6.9%, respectively. The estimated prevalence of atopic dermatitis was 5.9%, 11.3%, 14.6%, 3.9%, and 1.6%, respectively. Ten-year trends revealed a significant decrease in asthma prevalence in infants, preschool children, and the elderly. and in atopic dermatitis prevalence in infants and preschool children (<i>P</i><0.05 for all trends). Furthermore, 10-year trends demonstrated a significant increase in allergic rhinitis prevalence in school-age children, adults, and the elderly, and in atopic dermatitis prevalence in school-age children and the elderly (<i>P</i><0.05 for all trends).Conclusion: These results improve our understanding of the age-stratified epidemiology of allergic diseases in Korea and suggest the need for the development of tailored and precise strategies to prevent allergic diseases in different age groups.

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