A systematic review and meta-analysis on the association between lymphocyte subsets and the severity of COVID-19

Introduction: Prominent prognostic parameters that reflect the severity of coronavirus disease 2019 (COVID-19) to adopt an appropriate therapeutic approach are not fully identified. This systematic review and meta-analysis aimed to explore the association between lymphocyte variation and disease severity in COVID-19 individuals. Methods: We searched Web of Science, Scopus, PubMed, EMBASE and WHO website to retrieve studies investigating lymphocyte subset counts in non-severe and severe cases of COVID-19. The pooled standardized mean difference (SMD) between two groups and the pooled average count of each lymphocyte subset were assessed by employing a random-effect model. Results: Thirty-nine investigations on 5087 participants, including 3578 non-severe patients and 1509 severe patients, were included. The pooled analysis showed that non-severe patients had higher total T lymphocytes (SMD = 1.01;95% CI: 0.82, 1.20;I2 = 75.7%), T helper cells (SMD = 1.07;95% CI: 0.85, 1.28;I2 = 85.4%), T cytotoxic cells (SMD = 1.07;95% CI: 0.82, 1.32;I2 = 87.1%), B cells (SMD = 0.72;95% CI: 0.45, 0.98;I2 = 79.7%), and natural killer cells (SMD = 0.65;95% CI: 0.47, 0.84;I2 = 63.1%) than severe patients and the average count of the corresponding lymphocyte signatures in non-severe patients/severe patients were 878.88/448.40, 493.12/268.96, 311.91/158.91, 177.09/110.37, and 155.02/103.09 cells/mu L, respectively. Conclusion: Lymphopenia may be a dilemma in COVID-19 management because over-activation of lymphocytes may lead to cytokine storm or acute respiratory distress syndrome (ARDS). In contrast, lymphopenia may increase SARS-CoV-2 amplification and COVID-19 severity. Therefore, novel therapies targeting lymphocyte proliferation or contraction may counterbalance lymphocyte counts in these patients.

Accuracy of chest computed tomography and reverse transcription polymerase chain reaction in diagnosis of 2019 novel coronavirus disease;a systematic review and meta-analysis

Introduction: This study aims to measure the diagnostic accuracy of chest computed tomography (CT) and reverse transcription polymerase chain reaction assay (RT-PCR) in COVID-19 in a systematic review and metaanalysis. Methods: PubMed, Scopus, Embase, and Google Scholar, WHO, SSRN, and MedRxiv have been searched on March 26, 2020 for all the alternative names of the disease and virus. Risk of bias assessment was based on QUADAS-2. Data from English-language studies after January 12, 2019 were pooled to calculate necessary diagnostic values and underwent diagnostic test accuracy, random-effects, proportions, and subgroup metaanalysis. Results: Pooled from 27 included studies, the sensitivity of chest CT was calculated 96.6%, specificity 22.5%, diagnostic odds ratio (DOR) 8.2, positive likelihood ratio (PLR) 1.2 (95% CI: 1.1-1.4), and negative likelihood ratio (NLR) 0.15 (95% CI: 0.1-0.3). The sensitivity for initial RT-PCR was 79.7%, the specificity 100%, and NLR 0.18. Conclusion: Considering the results, in order to diagnose COVID-19 (coronavirus disease 2019), it is recommended to initially performing chest CT to rule out the uninfected people. In suspicious cases, we suggest RT-PCR to confirm the disease. Performing serial RT-PCR instead of the one-time test is highly recommended, to let the viral loads reach the diagnostic levels, especially in cases of high clinical suspicion.

An overview of the prominence of current diagnostic methods for diagnosis of COVID-19

Coronavirus disease 2019 (COVID-19) caused a fatal pandemic worldwide. This review aims to discuss laboratory, molecular, and serological methods and their advantages and disadvantages over each other in COVID-19 diagnosis. Moreover, computed tomography (CT) scan, that is used on suspicion of COVID-19 pneumonia and for determining the severity and progression of the disease, is also discussed. Different CT features categorize the patients into low to high-risk groups. Here, we described three kinds of CT classification based on CT patterns within different time courses of the disease. Chest CT imaging should be considered for screening, evaluating, and following up COVID-19 due to its high sensitivity. Approximately, shortly after the onset of symptoms, viral load can be diagnosed by real-time PCR technique through bronchoalveolar lavage, nasopharyngeal and/or oropharyngeal swab sampling. Proper sampling may delineate the result of this test. Although RT-PCR assay is currently considered the gold standard test, false-negative results should be considered. Furthermore, a positive test may indicate the infection with SARS-CoV-2, but not necessarily the disease, and the person may be a carrier or other organs may be involved other than the lungs. In contrast to CT imaging, RT-PCR assay has poor sensitivity, but it helps the decision-making on hospitalization and isolation. The emergence of reliable serological tests has promoted the diagnosis, treatment process, chronic or carrier status of an individual, and epidemiological studies. In addition, an earlier and more accurate diagnosis will be provided for asymptomatic or susceptible individuals.