Differential Diagnosis of Coronavirus Disease 2019 from Pneumonias Caused by Other Etiologies in a Fever Clinic in Beijing
Coronavirus disease 2019 (COVID-19) is an acute respiratory infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). During the early stages of the COVID-19 outbreak, fever clinics in general hospitals played a critical role in identifying and managing suspected cases. Patients with body temperatures ≥37.3°C were directed to these clinics, where a triage strategy was implemented to identify probable or possible cases. Given the prevalence of other respiratory infections, such as influenza, during the same period, distinguishing COVID-19 from pneumonias caused by other etiologies posed a significant challenge for physicians. This study aimed to provide insights into the differential diagnosis of COVID-19 in a fever clinic setting in Beijing.
The study was conducted retrospectively at the fever clinic of Peking University Third Hospital from January 21 to February 15, 2020. Patients were recruited based on epidemiological history, clinical symptoms, and radiological findings. Cases with possible or probable COVID-19 were referred to a multidisciplinary panel for discussion and subsequently tested for SARS-CoV-2 using reverse transcription-polymerase chain reaction (RT-PCR). Pediatric patients were excluded from the study. The diagnosis and severity assessment of COVID-19 were based on the Guidelines for the Diagnosis and Treatment of Novel Coronavirus (2019-nCoV) Infection issued by the National Health Commission of China. Laboratory testing for SARS-CoV-2 was performed by the Beijing Center for Disease Control and Prevention (CDC) and the Haidian District CDC of Beijing.
Demographic and epidemiological data were collected, including whether the patient had traveled to Wuhan or other cities in Hubei Province within the past two weeks, had close contact with individuals from these areas, or had contact with confirmed COVID-19 cases. Clinical symptoms and laboratory findings, including blood tests and computed tomography (CT) scans, were also recorded. CT findings were reviewed by experts in Pulmonary and Critical Care Medicine and Radiology. Statistical analyses were performed using SPSS software, version 22.0, with continuous variables expressed as mean ± standard deviation or median (interquartile range) and categorical variables as numbers (%). Differences between groups were analyzed using Student’s t-test, Mann-Whitney U test, Chi-square test, or Fisher’s exact test, with a significance level of P < 0.05.
During the study period, 156 cases were referred to the multidisciplinary panel for discussion, of which 110 were considered possible or probable COVID-19 cases and underwent SARS-CoV-2 RT-PCR testing. Nineteen cases tested positive for SARS-CoV-2 (COVID-19 group), while 91 cases tested negative. After excluding cases without CT scans or signs of pneumonia, 67 patients were included in the non-COVID-19 group for comparison.
The median age of COVID-19 patients was 44.0 years, with an equal distribution of men and women. Seventeen of the 19 COVID-19 patients (89.5%) had a clear epidemiological history, including close contact with family members who were infected with SARS-CoV-2. The incubation period ranged from 2 to 10 days, with a median of 6.0 days. Most patients (89.5%) had mild to moderate disease severity, while two were classified as severe cases with pulse oxygen saturation (SpO2) ≤93% on presentation. No critical cases were identified.
On admission, 89.5% of COVID-19 patients presented with fever, with a mean body temperature of 37.8°C. Common symptoms included cough (36.8%), expectoration (31.6%), fatigue (52.6%), and headache or dizziness (36.8%). Other symptoms included shortness of breath, myalgia or arthralgia, sore throat, nasal symptoms, and diarrhea. Compared to non-COVID-19 patients, a significantly higher proportion of COVID-19 patients had a clear epidemiological history (89.5% vs. 32.8%, P < 0.001). Clinical symptoms were similar between the two groups, except for cough, which was more prevalent in non-COVID-19 patients (79.1% vs. 36.8%, P < 0.001).
Blood tests revealed that 42.1% of COVID-19 patients had decreased lymphocyte counts, while more than 80% had normal white blood cell (WBC) and neutrophil counts. Compared to non-COVID-19 patients, COVID-19 patients had significantly lower total WBC counts (5.30 ± 1.48 × 10^9/L vs. 7.21 ± 2.94 × 10^9/L, P < 0.001) and neutrophil counts (3.10 × 10^9/L vs. 4.45 × 10^9/L, P = 0.006). Leukocytosis and neutrophilia were more common in non-COVID-19 patients, with 20.9% and 31.3% showing increased WBC and neutrophil counts, respectively, compared to 0.0% and 5.3% in COVID-19 patients.
CT findings showed that COVID-19 patients were more likely to have multi-lobe involvement, with 50.0% having lesions in 4–5 lobes compared to 16.4% in non-COVID-19 patients (P = 0.009). In COVID-19 patients, lung lesions were predominantly peripheral or sub-pleural in distribution (77.8%), while severe cases exhibited diffuse lesions (22.2%). In contrast, 34.3% of non-COVID-19 patients showed airway-dominant lesions, and only 4.5% had diffuse distribution. The patterns of lesions, including ground-glass opacity (GGO), consolidation, or mixed GGO and consolidation, did not differ significantly between the two groups. However, centrilobular nodules were observed exclusively in non-COVID-19 patients.
The study highlighted the importance of epidemiological history in identifying suspected COVID-19 cases. Over 90% of COVID-19 patients had clear epidemiological evidence, compared to only about 30% of non-COVID-19 patients. In the early phase of the study, most cases were imported from Wuhan or other cities in Hubei Province, while later cases were linked to family clusters. Lower blood WBC and neutrophil counts were useful in differentiating COVID-19 from pneumonias caused by other etiologies. Persistent lymphopenia was noted as a predictor of severe COVID-19 cases.
In conclusion, this study provided valuable insights into the differential diagnosis of COVID-19 in a fever clinic setting. Epidemiological history, clinical symptoms, and laboratory and radiological findings were critical in distinguishing COVID-19 from other pneumonias. Lower WBC and neutrophil counts, along with multi-lobe involvement on CT scans, were key indicators of COVID-19. These findings contribute to the clinical management of respiratory infections in fever clinics, particularly during the early stages of an emerging epidemic. However, the study’s limitations, including its single-center design and small sample size, underscore the need for larger, multicenter studies to further validate these findings.
doi.org/10.1097/CM9.0000000000001121
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