We aimed to identify whether lymphopenia is a reliable prognostic marker for COVID-19. Using data derived from a Korean nationwide longitudinal cohort of 5628 COVID-19 patients, we identified propensity-matched cohorts (n = 770) with group I of severe lymphopenia (absolute lymphocyte counts [ALC]: <500/mm³, n = 110), group II of mild-to-moderate lymphopenia (ALC: ≥500–<1000/mm³, n = 330), and group III, no lymphopenia (ALC: ≥1000/mm³, n = 330). A significantly higher mortality rate was associated with lymphopenia severity: 40% in group I, 22.7% in group II, and 13.0% in group III (p < 0.001). At 28 days, the estimated inferior overall survival associated with intensified lymphopenia: 62.7% in group I, 79.9% in group II, and 89.0% in group III (p < 0.001). Lymphopenia contributed significantly toward a greater need for interventions in all groups but at varying degrees: requirements of invasive ventilation, intensive oxygen supply, or adequate oxygen supply, respectively (p < 0.001). The lymphopenia intensity was independently associated with higher COVID-19 mortality in multivariable analysis; adjusted odds ratios of 5.63 (95% CI, 3.0–10.72), and 2.47 (95% CI, 1.5–4.13) for group I and group II, respectively. Lymphopenia and its severity levels may serve as reliable predictive factors for COVID-19 clinical outcomes; thus, lymphopenia may provide the prognostic granularity required for clinical use in the management of patients with COVID-19.

Preventing exacerbation in chronic obstructive pulmonary disease (COPD) patients is crucial, but requires identification of the exacerbating factors. To date, no integrated analysis of patient-derived and external factors has been reported. To identify factors associated with COPD exacerbation, we collected data, including smoking status, lung function, and COPD assessment test scores, from 594 COPD patients in the Korean COPD subgroup study (KOCOSS), and merged these data with patients’ Korean Health Insurance Review and Assessment Service data for 2007–2012. We also collected primary weather variables, including levels of particulate matter <10 microns in diameter, daily minimum ambient temperature, as well as respiratory virus activities, and the logs of web queries on COPD-related issues. We then assessed the associations between these patient-derived and external factors and COPD exacerbations. Univariate analysis showed that patient factors, air pollution, various types of viruses, temperature, and the number of COPD-related web queries were associated with COPD exacerbation. Multivariate analysis revealed that the number of exacerbations in the preceding year, female sex, COPD grade, and influenza virus detection rate, and lowest temperature showed significant association with exacerbation. Our findings may help COPD patients predict when exacerbations are likely, and provide intervention as early as possible.

Sojeong Yun, B.S., Ji Hyeong Ryu, M.S., Joo Hee Jang, B.S., Hyunjoo Bae, M.S., Seung-Hyo Yoo, M.T., Ae-Ran Choi, M.T., Sung Jin Jo, M.D., Jihyang Lim, M.D., Jehoon Lee, M.D., Hyejin Ryu, M.D., Sung-Yeon Cho, M.D., Dong-Gun Lee, M.D., Jongmin Lee, M.D., Seok Chan Kim, M.D., Yeon-Joon Park, M.D., Hyeyoung Lee, M.D., and Eun-Jee Oh, M.D.. Ann Lab Med 2021;41:577-87. https://doi.org/10.3343/alm.2021.41.6.577

Background: There are only a few longitudinal studies regarding medical utilization and costs for patients with COPD. The purpose of this study was to analyze the trend of medical utilization and costs on a long-term basis. Methods: Using the Korean Health Insurance Review and Assessment Service (HIRA) data from 2008 to 2013, COPD patients were identified. The trend of medical utilization and costs was also analyzed. Results: The number of COPD patients increased by 13.9% from 2008 to 2013. During the same period, the cost of COPD medication increased by 78.2%. Methylxanthine and systemic beta agonists were most widely prescribed between 2008 and 2013. However, inhaled medications such as long-acting beta-2 agonist (LABA), long-acting muscarinic agonist, and inhaled corticosteroid plus LABA were dispensed to a relatively low proportion of patients with COPD. The number of patients who were prescribed inhaled medications increased gradually from 2008 to 2013, while the number of patients prescribed systemic beta agonist and methylxanthine has decreased since 2010. Conclusion: This study shows that there is a large gap between the COPD guidelines and clinical practice in Korea. Training programs for primary care physicians on diagnosis and guideline-based treatment are needed to improve the management of COPD.

Quantitative SARS-CoV-2 antibody assays against the spike (S) protein are useful for monitoring immune response after infection or vaccination. We compared the results of three chemiluminescent immunoassays (CLIAs) (Abbott, Roche, Siemens) and a surrogate virus neutralization test (sVNT, GenScript) using 191 sequential samples from 32 COVID-19 patients. All assays detected >90% of samples collected 14 days after symptom onset (Abbott 97.4%, Roche 96.2%, Siemens 92.3%, and GenScript 96.2%), and overall agreement among the four assays was 91.1% to 96.3%. When we assessed time-course antibody levels, the Abbott and Siemens assays showed higher levels in patients with severe disease (p < 0.05). Antibody levels from the three CLIAs were correlated (r = 0.763–0.885). However, Passing–Bablok regression analysis showed significant proportional differences between assays and converting results to binding antibody units (BAU)/mL still showed substantial bias. CLIAs had good performance in predicting sVNT positivity (Area Under the Curve (AUC), 0.959–0.987), with Abbott having the highest AUC value (p < 0.05). SARS-CoV-2 S protein antibody levels as assessed by the CLIAs were not interchangeable, but showed reliable performance for predicting sVNT results. Further standardization and harmonization of immunoassays might be helpful in monitoring immune status after COVID-19 infection or vaccination.