Changes in Otorhinolaryngologic Disease Incidences before and during the COVID-19 Pandemic in Korea.

This study aimed to investigate the change in the incidence and variance of otorhinolaryngologic diseases during the coronavirus disease 19 (COVID-19) pandemic. The entire Korean population (~50 million) was evaluated for the monthly incidence of 11 common otorhinolaryngologic diseases of upper respiratory infection (URI), influenza, acute tonsillitis, peritonsillar abscess, retropharyngeal and parapharyngeal abscess, acute laryngitis and bronchitis, stomatitis and related lesions, acute sinusitis, rhinitis, otitis media, and dizziness from January 2018 through March 2021 using the International Classification of Disease (ICD)-10 codes with the data of the Korea National Health Insurance Service. The differences in the mean incidence of 11 common otorhinolaryngologic diseases before and during COVID-19 were compared using the Mann-Whitney U test. The differences in the variance of incidence before and during COVID-19 were compared using Levene's test. The incidence of all 11 otorhinolaryngologic diseases was lower during COVID-19 than before COVID-19 (all p < 0.05). The variations in disease incidence by season were lower during COVID-19 than before COVID-19 for infectious diseases, including URI, influenza, acute tonsillitis, peritonsillar abscess, retropharyngeal and parapharyngeal abscess, acute laryngitis and bronchitis, acute sinusitis, and otitis media (all p < 0.05), while it was not in noninfectious diseases, including stomatitis, rhinitis, and dizziness. As expected, the incidences of all otorhinolalryngolgic diseases were decreased. Additionally, we found that seasonal variations in infectious diseases disappeared during the COVID-19 pandemic, while noninfectious diseases did not.

Changes in mean and variance of ophthalmic disease incidences during COVID-19 pandemic in Korea.

This study undertook to determine the changes in the numbers of outpatient visits for various ophthalmic diseases during the COVID-19 pandemic compared with before. The monthly outpatient visits for 14 common ophthalmic diseases were enumerated based on the ICD-10 codes in Korean National Health Insurance Service data. The differences in the mean outpatient visits and disease variance 'before' and 'during COVID-19' were calculated. Subsequently, subgroup analyses according to age and sex were performed. The number of outpatient visits for conjunctivitis, scleritis & episcleritis, keratitis, cataract, diabetic retinopathy, and traumatic ophthalmic disease were lower during than before COVID-19 (all P < 0.001). The lower numbers of outpatient visits for ophthalmic disorders during COVID-19 were consistent across the age and sex subgroups. All ophthalmic diseases other than endophthalmitis showed no change of variation 'during' relative to 'before' COVID-19. In conclusion, during the COVID-19 pandemic, the ophthalmic outpatient visits decreased for infectious and inflammatory diseases, screening diseases, and traumatic diseases. However, COVID-19 is not considered to have had a significant effect on variation.

Incidence of Asthma, Atopic Dermatitis, and Allergic Rhinitis in Korean Adults before and during the COVID-19 Pandemic Using Data from the Korea National Health and Nutrition Examination Survey.

The prevalence of allergic diseases has been increasing globally prior to COVID-19. The pandemic resulted in changes in lifestyle and personal habits such as universal mask-wearing and social distancing. However, there is insufficient information on the impact of the COVID-19 pandemic on the prevalence of allergic conditions such as asthma, atopic dermatitis, and allergic rhinitis. We analyzed the incidence rate for self-reported and doctor-diagnosed cases of allergic diseases of asthma, atopic dermatitis, and allergic rhinitis. A total of 15,469 subjects were registered from a national cohort dataset of the National Health and Nutrition Examination Survey. Using multiple logistic regression analysis, we calculated the adjusted odds ratio (OR) for each disease in 2020 compared to 2019. Subgroup analyses were performed according to age and sex. There were no statistically significant differences between the incidence of doctor-diagnosed and current allergic diseases in 2019 and 2020 (asthma, p = 0.667 and p = 0.268; atopic dermatitis, p = 0.268 and p = 0.973; allergic rhinitis, p = 0.691 and p = 0.942, respectively), and subgroup analysis showed consistent results. Among the Korean population from 2019 to 2020, the incidence of the allergic diseases asthma, atopic dermatitis, and allergic rhinitis did not decrease as expected.

Depression, Stress, and Suicide in Korean Adults before and during the COVID-19 Pandemic Using Data from the Korea National Health and Nutritional Examination Survey.

This study investigated changes in the prevalence of depression, stress, and suicidal attempts during the COVID-19 pandemic. The ≥19-year-old population in the Korea National Health and Nutrition Examination Survey in 2019 and 2020 was included. The histories of depression, stress, and suicidal attempts were compared between the 2019 and 2020 cohorts using multiple logistic regression analysis with complex sampling. The prevalence of depression was not significantly different between the 2019 and 2020 groups (4.1% vs. 4.5%, p = 0.326). The prevalence of stress and suicide attempts was also not significantly different between groups (all p > 0.05). The rates of depression, stress, and suicide attempts were not associated with the 2020 group compared to the 2019 group (all p > 0.05). The 19- to 39-year-old group in the 2020 group indicated a higher rate of depression (diagnosed by physicians) than the 19- to 39-year-old group in the 2019 group (adjusted odds ratio = 1.58, 95% confidence intervals = 1.00-2.50, p = 0.049). The risks of depression, stress, and suicidal attempts were not related to the COVID-19 pandemic in Korean adults. A young adult population demonstrated an increased risk of depression associated with the COVID-19 pandemic.

Physical Activity and Sedentary Time in Korean Adults before and during the COVID-19 Pandemic Using Data from the Korea National Health and Nutritional Examination Survey.

Several recent studies suggested reduced physical activity (PA) related to the COVID-19 pandemic without consensus. This study investigated the changes in PA and sedentary time during the COVID-19 pandemic compared to before the COVID-19 era. The Korea National Health and Nutrition Examination Survey 2019 and 2020 were used. The ≥19-year-old population was examined in 2019 and 2020 for time spent engaging in high- and moderate-intensity PA and sedentary time. Based on the recommended level of PA by the World Health Organization, ≥75 min/wk of high PA and ≥150 min/of moderate PA were classified. A sedentary time of ≥120 min/d was selected. Multiple logistic regression analysis with complex sampling was conducted for ≥75 min/wk of high PA, ≥150 min/wk of moderate PA, and ≥120 min/d of sedentary time in the 2020 group compared to the 2019 group. The ≥75 min/wk high PA was not lower in the 2020 group than in the 2019 group (adjusted odds ratio (aOR) = 0.96, 95% confidence intervals (95% CIs) = 0.79-1.18, P = 0.696). The ≥150 min/wk of moderate PA was also not lower in the 2020 group (aOR = 1.12, 95% CI = 0.94-1.32, p = 0.201). However, the ≥150 min/wk of moderate PA in the female group was higher in the 2020 group than in the 2019 group (aOR = 1.29, 95% CI = 1.01-1.65, p = 0.042). Sedentary time ≥ 120 min/d was lower in the 2020 group (aOR = 0.35, 95% CI = 0.17-0.72, p = 0.005). This association was consistent in the 19-39-year-old and female group. In conclusion, during the COVID-19 pandemic, high and moderate PA were not decreased in Korean adults, while sedentary time was reduced.

Changes in the Mean and Variance of the Numbers of Medical Visits for Allergic Diseases before and during the COVID-19 Pandemic in Korea.

The implementation of precautionary measures, such as wearing a mask and social distancing, may have affected allergic diseases during the coronavirus disease 2019 (COVID-19) pandemic. This study aimed to compare the numbers of medical visits for allergic diseases before and during the COVID-19 pandemic. Data were obtained from the Korean National Health Insurance claims database. Monthly numbers of patients for four allergic diseases, i.e., allergic rhinitis (AR), asthma, atopic dermatitis (AD), and allergic conjunctivitis (AC), were evaluated using ICD-10 codes and compared between the 'before COVID-19' period from January 2018 to February 2020, and the 'during COVID-19' period from March 2020 to June 2021, since the first COVID-19 patient was detected on 20 January 2020, in Korea. Subgroup analyses were performed according to age and sex. The mean numbers of medical visits for AR and asthma were significantly greater before COVID-19 than those during COVID-19 (both p < 0.001). The variance in the number of medical visits for asthma decreased during the COVID-19 pandemic. However, the mean number of medical visits for AD increased slightly during COVID-19 and that for AC did not change before and during the COVID-19 pandemic. In subgroup analyses, the results showed a similar pattern to that of the total number of participants, regardless of age and sex. In conclusion, medical visits for AR and asthma significantly decreased during the COVID-19 pandemic, regardless of age and sex.

Changes in the Incidence of Cardiovascular Diseases during the COVID-19 Pandemic in Korea.

There is scarcity in the evidence addressing the indirect impact of the COVID-19 pandemic on the epidemiology of CVDs. In this study we aimed to examine possible changes in the incidence of CVDs in Korea during the COVID-19 pandemic. ICD-10 codes of six common CVDs (cerebral hemorrhage, cerebral infarction, myocardial infarction, ischemic heart disease, cardiac failure, and arrhythmia) were collected from clinical visits between January 2018 and March 2021 using the National Health Insurance service database, which stores data on all citizens of Korea (~50 million people). The number and distribution of monthly visits for CVDs were compared before and during the COVID-19 pandemic, and the differences were analyzed using the Mann-Whitney U test and Levene's test. Our data showed similar incidences of cerebral hemorrhage and ischemic heart disease, a lower incidence of cerebral infarction, and higher incidences of myocardial infarction, cardiac failure, and arrhythmia during COVID-19. Despite statistical differences, the changes in incidences were not considered meaningful. The monthly incidences also remained similar throughout the year, without seasonal variations, both before and during the COVID-19 outbreak. This study found no significant changes in the incidences or monthly variation in CVDs due to the COVID-19 pandemic in Korea.

Changes in the Incidence Rates of Gastrointestinal Diseases Due to the COVID-19 Pandemic in South Korea: A Long-Term Perspective.

We investigated whether the coronavirus disease 2019 (COVID-19) pandemic, in conjunction with public health measures, influenced the incidence of gastrointestinal diseases according to age and sex during the pandemic. Changes in the monthly incidence rates (January 2018 to June 2021) of common gastrointestinal diseases were assessed using data from the Korean National Health Insurance Service by comparing the data of two periods: before COVID-19 (January 2018-February 2020) and during COVID-19 (March 2020-June 2021). The Mann-Whitney U test and Levene's test were used to compare the differences in the incidences before and during the pandemic. In the pandemic period, compared to in the pre-COVID-19 period, the incidence rates of ulcerative colitis, Crohn's disease, cholelithiasis, and esophageal reflux significantly increased, whereas those of infective enteritis and irritable bowel syndrome decreased, regardless of age or sex. There were no significant changes in the incidence rates of pancreatitis, acute appendicitis, liver cirrhosis, and hemorrhoids. No seasonal variations in gastrointestinal disease occurrence were observed. In conclusion, the COVID-19 pandemic may have had unprecedented and long-term impacts on the epidemiology of gastrointestinal disease. These changes may indicate a substantial future burden on healthcare resources during the recovery phase of the pandemic and thereafter.

Investigation of changes in the physical activity and fall experience before and after the COVID-19 pandemic.

This study aimed to investigate the changes in physical activity levels and the rate of falls during the COVID-19 pandemic in the Korean population. The Korean Community Health Survey (KCHS) conducted in 2019 was compared with that conducted in 2020. Simple or multiple linear regression with complex sampling was conducted to calculate the estimated value (EV) of physical activity in the 2020 group vs. the 2019 group. The odds ratio (OR) of fall histories was calculated using simple or multiple logistic regression with complex sampling for the 2020 group compared to the 2019 group. The time spent on vigorous and moderate physical activity was lower in the 2020 group than in the 2019 group (EV = -10.0, 95% CI = -12.1 to -8.0, P < 0.001 for vigorous exercise and EV = -24.0, 95% CI = -26.7 to -21.4, P < 0.001 for moderate exercise). The rate of falls was lower in the 2020 group than in the 2019 group (OR = 0.66, 95% CI = 0.62 to 0.70, P < 0.001). Vigorous and moderate exercise decreased after the COVID-19 pandemic compared to before the pandemic. The occurrence of falls was lower during the COVID-19 pandemic than in the pre-pandemic period.

Association Between Pneumonia and Chronic Otitis Media: A Nested Case-Control Study Using a National Health Screening Cohort.

BACKGROUND: Pneumonia and chronic otitis media (COM) share a common pathophysiological mechanism in terms of respiratory infection and inflammation, but the epidemiologic association between the 2 diseases has not been investigated. We investigated the association between an event of COM and previous events of pneumonia in a national cohort. METHODS: Data from the Korean National Health Insurance Service-Health Screening Cohort were collected from 2002 to 2015. A 1:4 stratified cohort matched for age, sex, income, and residence region composing the COM group (n=23,436) and a control group (n=93,744) was selected. The crude and adjusted odds ratios (ORs) of pneumonia occurring before the index date for COM were analyzed using a conditional logistic regression model. In addition, ORs of the number of diagnoses of pneumonia (≥5 times vs. <5 times) for COM were analyzed. RESULTS: The incidence of pneumonia (9.3%) was significantly higher (p<0.001) in the COM group than in the control group (7.2%). The ORs of pneumonia were significantly higher in the COM group than in the control group. Pneumonia (adjusted OR=1.31, 95% confidence interval [CI]=1.25-1.38, p<0.001) increased the ORs for COM in all ages and gender. Pneumonia being diagnosed ≥5 times before the index date showed higher ORs (adjusted OR=1.34, 95% CI=1.20-1.49, p<0.001) for COM than pneumonia being diagnosed <5 times. CONCLUSIONS: Our population-based nationwide cohort study indicates that diagnosis of pneumonia was significantly associated with an increased incidence of COM.

Changes in the Mean of Medical Visits Due to Psychiatric Disease in Korean Children and Adolescents before and during the COVID-19 Pandemic.

The COVID-19 pandemic has been suggested to have adverse impacts on psychiatric disorders. This study aimed to investigate the changes in medical visits due to a wide range of psychiatric disorders in children during the COVID-19 pandemic. The medical visits of all Korean children and adolescents (0-19 years old) due to the 12 following psychiatric disorders were investigated: autism; attention-deficit/hyperactivity disorder (ADHD); depressive disorder; bipolar disorder; primary insomnia; schizophrenia; panic disorder; hypochondriasis; posttraumatic stress disorder (PTSD); anxiety disorder; anorexia nervosa; and adephagia. The mean medical visits before and during the COVID-19 pandemic were compared. The mean number of clinical visits due to autism, ADHD, depressive disorder, bipolar disorder, panic disorder, hypochondriasis, PTSD, anxiety disorder, and anorexia nervosa was higher during the COVID-19 pandemic than before the COVID-19 pandemic (all p < 0.05). The higher mean number of medical visits due to psychiatric disorders was maintained in age and sex subgroups. The female and adolescent groups demonstrated a higher mean number of medical visits due to psychiatric disorders during the COVID-19 pandemic. The medical visits due to many psychiatric disorders were higher during the COVID-19 pandemic than before COVID-19 in children and adolescents in Korea. Women and adolescents were more susceptible to psychiatric disorders during the COVID-19 pandemic.

Changes in the Mean of and Variance in Psychological Disease Incidences before and during the COVID-19 Pandemic in the Korean Adult Population.

The coronavirus disease 2019 (COVID-19) pandemic has been suggested to increase the risk of depression and anxiety disorders. This study expanded upon previous findings by estimating the changes in medical visits for various psychological disorders during the COVID-19 pandemic compared to before COVID-19. The entire Korean population ≥ 20 years old (~42.3 million) was included. The first COVID-19 case in Korea was reported on 20 January 2020. Thus, the period from January 2018 through to February 2020 was classified as "before COVID-19", and the period from March 2020 through to May 2021 was classified as "during COVID-19". Monthly medical visits due to the following 13 psychological disorders were evaluated: depressive disorder, bipolar disorder, primary insomnia, schizophrenia, panic disorder, hypochondriasis, posttraumatic stress disorder (PTSD), anxiety disorder, anorexia nervosa, addephagia, alcoholism, nicotine dependency, and gambling addiction were evaluated. The differences in the number of medical visits and the variance of diseases before and during the COVID-19 pandemic were analyzed using the Mann-Whitney U test and Levene's test. Subgroup analyses were conducted according to age and sex. The frequencies of medical visits for depressive disorder, bipolar disorder, primary insomnia, panic disorder, hypochondriasis, PTSD, anxiety disorder, anorexia nervosa, addephagia, and gambling addiction were higher during COVID-19 than before COVID-19 (all p < 0.001). However, the frequencies of medical visits for schizophrenia, alcoholism, and nicotine dependency were lower during the COVID-19 pandemic than before the COVID-19 pandemic (all p < 0.001). The psychological disorders with a higher frequency of medical visits during COVID-19 were consistent in all age and sex subgroups. In the old age group, the number of medical visits due to schizophrenia was also higher during COVID-19 than before COVID-19 (p < 0.001). Many psychological disorders, including depressive disorder, bipolar disorder, primary insomnia, panic disorder, hypochondriasis, PTSD, anxiety disorder, anorexia nervosa, addephagia, and gambling addiction, had a higher number of related medical visits, while disorders such as schizophrenia, alcoholism, and nicotine dependency had a lower number of related medical visits during COVID-19 among Korean adults.

Physical Activity Is Associated with a Lower Risk of Osteoporotic Fractures in Osteoporosis: A Longitudinal Study.

The purpose of our study was to examine the occurrence of osteoporotic fractures (fxs) according to the level of physical activity (PA) among osteoporosis using the Korean National Health Insurance Service (NHIS) customized database. From NHIS data from 2009 to 2017, osteoporosis was selected as requested. PA was classified into 'high PA' (n = 58,620), 'moderate PA' (n = 58,620), and 'low PA' (n = 58,620) and were matched in a 1:1:1 ratio by gender, age, income within the household unit, and region of residence. A stratified Cox proportional hazard model was used to calculate hazard ratios (HRs) for each type of fx comparing PA groups. The 'low PA' group was the reference group. For vertebral fx, the adjusted HR (95% confidence intervals (CIs)) was 0.27 (0.26-0.28) for the 'high PA' group and 0.43 (0.42-0.44) for the 'moderate PA' group. For hip fx, the adjusted HR (95% CIs) was 0.37 (0.34-0.40) for the 'high PA' group and 0.51 (0.47-0.55) for the 'moderate PA' group. For distal radius fx, the adjusted HR (95% CIs) was 0.32 (0.30-0.33) for the 'high PA' group and 0.46 (0.45-0.48) for the 'moderate PA' group. The results of this study suggest that a higher intensity of PA is associated with a lower risk of osteoporotic fxs, including vertebral fx, hip fx, and distal radius fx.

The Association of Pre-existing Diagnoses of Alzheimer’s Disease and Parkinson’s Disease and Coronavirus Disease 2019 Infection, Severity and Mortality: Results From the Korean National Health Insurance Database

Objectives Despite the numerous studies on coronavirus disease 2019 (COVID-19), data regarding the impact of pre-existing diagnoses of Alzheimer’s disease (AD) and Parkinson’s disease (PD) on the susceptibility to and outcome of COVID-19 are limited. We aimed to determine whether patients with AD/PD had a higher likelihood of contracting COVID-19 and experiencing worse outcomes. Methods Data from patients with confirmed diagnoses of COVID-19 (n = 8,070) from January to June 2020 and control participants (n = 121,050) who were randomly selected to match the patients on the basis of age and sex were extracted from the Korean National Health Insurance Database. Pre-existing diagnoses of AD and PD were identified based on medical claim codes. The associations of pre-existing AD or PD with contracting COVID-19, developing severe COVID-19 and dying due to COVID-19 were examined using a logistic regression model. The participants’ age, sex, income, comorbidity score, and history of hypertension/diabetes were assessed as covariates. Results COVID-19 cases were more likely to have a pre-existing AD diagnosis (adjusted odds ratio [aOR] = 2.11, 95% confidence interval [CI] = 1.79–2.50, P-value < 0.001) than controls. COVID-19 cases were more likely to have a pre-existing PD diagnosis than controls, although this estimate did not quite reach statistical significance (aOR = 1.41, 95% CI = 1.00–2.00, P-value = 0.054). Pre-existing AD was related to severe disease and mortality from COVID-19 (aOR = 2.21, 95% CI = 1.64–2.98;aOR = 2.21, 95% CI = 1.00–2.00). Pre-existing PD was not associated with mortality (aOR = 1.54, 95% CI = 0.75–3.16) but was associated with severe disease (aOR = 2.89, 95% CI = 1.56–5.35). Conclusion We found that COVID-19 infection was significantly associated with a pre-existing diagnosis of AD but not with a pre-existing diagnosis of PD. Patients with pre-existing AD had higher odds of developing severe COVID-19 and dying. Pre-existing PD was only associated with a higher odds of developing severe COVID-19.

Physical Activity, Sunshine Duration, and Osteoporotic Fractures: A Nested Case-Control Study.

This study examined the associations between the occurrence of osteoporotic fractures in detailed sites and combined physical activity (PA) and sunshine duration (SD). Data from the Korean National Health Insurance Service-National Health Screening Cohort for 7-year periods and from the Korea Meteorological Administration were used. Osteoporotic fractures (n = 12,103), including vertebral fractures, hip fractures, and distal radius fractures, and matched controls (n = 24,206) were selected in 1:2 ratios by age, sex, income, and region of residence. PA was classified as moderate- to high-intensity PA (High PA) and low-intensity PA (Low PA). SD was classified as Short SD (<6.1 h) and Long SD (≥6.1 h). Conditional logistic regression was used to calculate the odds ratios (ORs) with 95%-confidence intervals (CIs) of the combined PA and SD groups for the occurrence of each osteoporotic fracture. Compared to 'Low PA + Short SD', the adjusted ORs (95% CIs) for vertebral fracture in 'High PA + Short SD' and 'High PA + Long SD' were 0.83 (0.76-0.91) and 0.84 (0.77-0.92), respectively. Hip/distal radius fractures were not associated with the combined PA and SD group. We suggest that a higher intensity of PA is inversely associated with the risk of vertebral fracture.

Assessment of the difference in depressive symptoms of the Korean adult population before and during the COVID-19 pandemic using a community health survey.

BACKGROUND: The aim of this study was to evaluate the rate of depression during the COVID-19 pandemic compared to that during the prepandemic period. METHODS: Data from participants in the Korean Community Health Survey in 2019 and 2020 aged ≥ 19 years old were analyzed. In total, the data of 223,306 participants from the 2020 group were compared with the data of 217,133 participants from the 2019 group regarding the experience and severity of depression. The experience of depression was surveyed in terms of a history of sadness or despair for ≥2 weeks in the last year. In addition, the PHQ-9 scores were used, and participants with PHQ-9 scores ≥10 were recategorized as having moderate to severe depression. The odds for depression of the 2020 group compared to the 2019 group based on the survey and PHQ-9 scores were calculated using simple or multiple logistic regression with complex sampling with weighted values. RESULTS: The rate of depression experience was lower in the 2020 group than in the 2019 group. The odds of experiencing depression were lower in the 2020 group than in the 2019 group (adjusted odds ratio [aOR] = 0.95, 95% confidence intervals [95% CI] = 0.91-0.98, P = 0.004). The odds of moderate to severe depression were also lower in the 2020 group than in the 2019 group (aOR=0.92, 95% CI=0.88-0.97, P = 0.001). CONCLUSION: The rate of depression experience was not higher during the COVID-19 pandemic than during the prepandemic period in Korea.

Comparison of Stress and Suicide-Related Behaviors Among Korean Youths Before and During the COVID-19 Pandemic.

Importance: The COVID-19 pandemic has had a substantial psychological effect on young people. A quantitative assessment of the association between the pandemic and stress and suicidality in youths is needed. Objective: To investigate the association of the COVID-19 pandemic with self-reported stress and suicide-related behaviors in youths. Design, Setting, and Participants: This cross-sectional study used data from the the Korea Youth Risk Behavior Web-based Survey (KYRBWS) conducted in 2019 and 2020 with youths aged 12 to 18 years. Statistical analysis was performed from January to February 2021. Main Outcomes and Measures: The odds ratios (ORs) with 95% CIs for subjective stress level, sadness or despair, suicidal thoughts, suicide planning, and suicide attempts among 2020 participants were compared with those of the 2019 participants using multiple logistic regression analysis with complex sampling using weighted values. Results: The 48 443 youths in the 2019 KYRBWS (24 917 male youths [51.3%]; mean [SD] age, 15.0 [1.7] years) and the 44 216 youths in the 2020 KYRBWS (23 103 male youths [52.5%]; mean [SD] age, 15.1 [1.7] years) were compared. The degree of subjective stress was lower in the 2020 participants than in the 2019 participants (severe stress: adjusted OR [aOR], 0.90 [95% CI, 0.83-0.97]; very severe stress: aOR, 0.65 [95% CI, 0.60-0.72]). Sadness or despair was also lower in the 2020 participants than in the 2019 participants (aOR, 0.81 [95% CI, 0.78-0.84]). There were fewer suicide-related behaviors, including suicidal thoughts, suicide planning, and suicide attempts, among the 2020 participants than among the 2019 participants (suicidal thoughts: aOR, 0.77 [95% CI, 0.73-0.80]; suicide planning: aOR = 0.88 [95% CI, 0.81-0.96]; suicide attempts: aOR, 0.64 [95% CI, 0.58-0.70]). Conclusions and Relevance: This cross-sectional study found that severe stress, sadness or despair and suicide-related behaviors had inverse associations with the early COVID-19 pandemic in Korean youths. These findings suggest that levels of high stress decreased among Korean youths in the early period of the pandemic compared with prepandemic levels.

The associations of previous influenza/upper respiratory infection with COVID-19 susceptibility/morbidity/mortality: a nationwide cohort study in South Korea.

We aimed to investigate the associations of previous influenza/URI with the susceptibility of COVID-19 patients compared to that of non-COVID-19 participants. A nationwide COVID-19 cohort database was collected by the Korea National Health Insurance Corporation. A total of 8,070 COVID-19 patients (1 January 2020 through 4 June 2020) were matched with 32,280 control participants. Severe COVID-19 morbidity was defined based on the treatment histories of the intensive care unit, invasive ventilation, and extracorporeal membrane oxygenation and death. The susceptibility/morbidity/mortality associated with prior histories of 1-14, 1-30, 1-90, 15-45, 15-90, and 31-90 days before COVID-19 onset were analyzed using conditional/unconditional logistic regression. Prior influenza infection was related to increased susceptibility to COVID-19 (adjusted odds ratio [95% confidence interval] = 3.07 [1.61-5.85] for 1-14 days and 1.91 [1.54-2.37] for 1-90 days). Prior URI was also associated with increased susceptibility to COVID-19 (6.95 [6.38-7.58] for 1-14 days, 4.99 [4.64-5.37] for 1-30 days, and 2.70 [2.55-2.86] for 1-90 days). COVID-19 morbidity was positively associated with influenza (3.64 [1.55-9.21] and 3.59 [1.42-9.05]) and URI (1.40 [1.11-1.78] and 1.28 [1.02-1.61]) at 1-14 days and 1-30 days, respectively. Overall, previous influenza/URI did not show an association with COVID-19 mortality. Previous influenza/URI histories were associated with increased COVID-19 susceptibility and morbidity. Our findings indicate why controlling influenza/URI is important during the COVID-19 pandemic.

The Effects of Income Level on Susceptibility to COVID-19 and COVID-19 Morbidity/Mortality: A Nationwide Cohort Study in South Korea.

This study aimed to investigate the association of income level with susceptibility to coronavirus disease 2019 (COVID-19) and COVID-19 morbidity and mortality. Using the Korean National Health Insurance COVID-19 Database cohort, medical claim data from 2015 through 2020 were collected. A total of 7943 patients who were diagnosed with COVID-19 from 1 January 2020 to 4 June 2020 were included. A total of 118,914 participants had negative COVID-19 PCR tests. Income levels were classified by 20th percentiles based on 2019 Korean National Health Insurance premiums. The 20th percentile income levels were categorized into three groups (low, middle, and high). The relationship of income level with susceptibility to COVID-19 and COVID-19 morbidity and mortality was analyzed using logistic regression analysis. A high income level was related to lower odds of COVID-19 infection (adjusted odds ratio (aOR) = 0.79, 95% confidence interval (CI) = 0.75-0.83, p < 0.001). The negative association between income level and COVID-19 infection was maintained in all subgroups. Patients with low income levels were susceptible to COVID-19 infection; however, there was no relation of COVID-19 morbidity and mortality with income level in the Korean population.

The Effects of Previous Asthma and COPD on the Susceptibility to and Severity of COVID-19: A Nationwide Cohort Study in South Korea.

BACKGROUND: There is controversial evidence of the associations of asthma and chronic obstructive pulmonary disease (COPD) with the risk and outcomes of Coronavirus Disease 2019 (COVID-19). We aimed to evaluate the effects of asthma and COPD on the susceptibility to and severity of COVID-19. METHODS: Data from a nationwide COVID-19 cohort database by the Korea National Health Insurance Corporation were utilized. A total of 4066 COVID-19 patients (1 January 2020 through 4 June 2020) were 1:4 matched with 16,264 controls with regard to age, sex, and income. Asthma and COPD were defined as diagnostic codes (ICD-10) and medication claim codes. Conditional and unconditional multivariate logistic regression were applied to analyze the susceptibility to and severity of COVID-19 associated with asthma and COPD. RESULTS: The prevalence of mild and severe asthma/COPD did not differ between the COVID-19 and control patients in the multivariate analyses. Among the total 4066 COVID-19 patients, 343 (8.4%) had severe COVID-19, of whom 132 (3.2% of the total COVID-19 patients) died. Regarding the outcomes of COVID-19, neither mild nor severe asthma were associated with the severity or mortality of COVID-19 after adjusting for other variables. However, severe COPD was a significant risk factor for severe COVID-19 (odds ratio (OR) = 2.23, 95% confidence intervals (CI): 1.08-4.60, p = 0.030) and the mortality of COVID-19 in the multivariate analyses (OR = 3.06, 95% CI: 1.14-8.2, p = 0.026). CONCLUSIONS: In a Korean nationwide cohort, neither asthma nor COPD were associated with COVID-19, but severe COPD was associated with the severity and mortality of COVID-19.