Given that a substantial proportion of the subgroup of COVID-19 patients that face a severe disease course are younger than 60 years, it is critical to understand the disease-specific characteristics of young COVID-19 patients. Risk factors for a severe disease course for young COVID-19 patients and possible non-linear influences remain unknown. Data were analyzed from COVID-19 patients with clinical outcome in a single hospital in Wuhan, China, collected retrospectively from Jan 24th to Mar 27th. Clinical, demographic, treatment and laboratory data were collected from patients’ medical records. Uni- and multivariable analysis using logistic regression and random forest, with the latter allowing the study of non-linear influences, were performed to investigate the clinical characteristics of a severe disease course. A total of 762 young patients (median age 47 years, interquartile range [IQR] 38–55, range 18–60; 55.9% female) were included, as well as 714 elderly patients as a comparison group. Among the young patients, 362 (47.5%) had a severe/critical disease course and the mean age was statistically significantly higher in the severe subgroup than in the mild subgroup (59.3 vs. 56.0, Student’s t-test: p < 0.001). The uni- and multivariable analysis suggested that several covariates such as elevated levels of serum amyloid A (SAA), C-reactive protein (CRP) and lactate dehydrogenase (LDH), and decreased lymphocyte counts influence disease severity independently of age. Elevated levels of complement C3 (odds ratio [OR] 15.6, 95% CI 2.41–122.3; p = 0.039) are particularly associated with the risk of developing severe COVID-19 specifically in young patients, whereas no such influence seems to exist for elderly patients. Additional analysis suggests that the influence of complement C3 in young patients is independent of age, gender, and comorbidities. Variable importance values and partial dependence plots obtained using random forests delivered additional insights, in particular indicating non-linear influences of risk factors on disease severity. This study identified increased levels of complement C3 as a unique risk factor for adverse outcomes specific to young COVID-19 patients.
【저자키워드】 Risk factors, Diseases, 【초록키워드】 Treatment, severe COVID-19, Clinical characteristics, disease severity, Comorbidities, LDH, Gender, risk, risk factor, elderly patients, lactate dehydrogenase, Clinical outcome, adverse outcome, Lymphocyte count, Characteristics, clinical, female, Patient, Logistic regression, Mild, age, Critical, patients, COVID-19 patients, Analysis, Odds ratio, COVID-19 patient, Elderly patient, Complement C3, medical records, C-reactive protein (CRP, student, interquartile range, Factor, 95% CI, median age, laboratory data, disease course, serum amyloid, multivariable analysis, covariate, random, influences, variable, single hospital, severe disease course, independent, Wuhan, China, SAA, analyzed, performed, collected, proportion, elevated, unique, suggested, significantly higher, the mean, influence, statistically, 【제목키워드】 disease severity, risk factor, COVID-19 patient, Wuhan, China, unique,