This retrospective study identified high CT scores and COPD as risk factors for deterioration in hospitalized patients with COVID-19 in Wuhan, China. Additionally, being older and male, having chest tightness, hypertension, and elevated levels of D-dimer, C-reactive protein, α-hydroxybutyrate dehydrogenase, lactate dehydrogenase, creatine kinase, creatinine, and NLR were associated with progression to severe or critical COVID-19 illness.
Recently, Zhou et al. demonstrated that older age is associated with death in hospitalized COVID-19 patients in a retrospective, multicenter cohort study of 191 patients [10]. Other studies have also shown that older age (> 65 years) is associated with poorer clinical outcome in patients with COVID-19 [6, 11, 12]. The present study confirmed that more severely or critically ill patients were older (༞60 years) than patients with moderate type COVID-19 symptoms. The age-dependent risk has also been seen in previous studies of SARS and MERS [12, 13]. However, in this current study, older age was not shown to be an independent predictor of deterioration in hospitalized patients with COVID-19. The difference between the present and previous studies may be partly due to the different outcomes. The current study was aimed at the progress of moderate type patients with COVID-19 who eventually recovered, rather than died. Furthermore, we had a relatively small sample size for the severe or critical group.
Chest CT is the routine imaging modality for clinical diagnosis of patients with COVID-19 pneumonia in the Hubei Province. It may help to screen patients with suspected COVID-19 symptoms, especially those with a negative RT-PCR result at the early stages of the disease [14]. In order to comprehensively evaluate the CT features of COVID-19 pneumonia, a semi-quantitative scoring system has been developed to quantitatively estimate the severity of inflammation based on quantifying the extent of pulmonary abnormalities (including ground-glass opacities, consolidations, or other fuzzy interstitial opacities)[9]. Using this method, no significant differences of initial CT scores have been found between moderate type and severe/critical type groups. A recent study showed that CT scores in severe-critical type groups were significantly higher than those in the moderate type groups [15]. This may be explained by the fact that patients with COVID-19 in the present study were all of the moderate type initially. With the progression of COVID-19, there were significant differences in the highest CT scores between moderate type and severe/critical type groups. Moreover, using multivariable analysis, the maximum CT score indices were found to be an important independent predictor of deterioration of patients who progressed from moderate type symptoms to severe/critical type symptoms. Furthermore, ROC analysis showed an optimal cutoff value of a maximum score CT index of 11 (sensitivity of 85% and specificity of 78.3%) to predict deterioration. We hope that this maximum score CT index may be used to identify patients at earlier stages of COVID-19 who may potentially progress to severe/critical stage symptoms from moderate type symptoms. Patients with this maximum score CT index will then receive more aggressive treatment and close monitoring. However, the efficacy of such an approach remains to be validated in multi-center and large sample studies in the future.
Lung complications, especially COPD, are common in patients with pneumonia. According to a national cross-sectional study, the total number of patients with COPD in China approximates 100 million [16]. Most of the recent studies have shown no significant differences in COPD between patients with COVID-19 in non-severe types and severe types [1, 7, 17–19]. In the current study, COPD was more common in the severe/critical type group than those in the moderate type group, a finding which agreed with results reported by Guan et al [6]. In addition, COPD has been found to be associated with the deterioration of patients with COVID-19. It should be noted that all studies to date, including our study, have used small sample sizes of COVID-19 patients with COPD. The potential impact of COPD on the disease outcomes of patients with COVID-19 requires further observation and research.
Our study has some limitations. First, not all laboratory tests were done in all patients, including the measurement of levels of α-hydroxybutyrate dehydrogenase, lactate dehydrogenase, creatine kinase, procalcitonin and brain natriuretic peptide. Therefore, their roles might be underestimated in predicting disease progression. In addition, we did not analyze the changes in laboratory findings in the process of the disease progression or patient recovery. Some of these results might also contribute to the deterioration in some patients. Second, this was a retrospective study from a single center with a relatively small sample size and a certain selection bias, as some patients were transferred to other medical institution through government decree. Thus, comparisons of clinical characteristics, laboratory findings, and imaging features may be skewed. Third, the semi-quantitative methods for measuring COVID-19 pneumonia lesions may be somwhat subjectivie. Last, infants, children and adolescents were not included in the present study, and an effort should be made to include these groups in future studies.