Two Consecutive Visits to the Emergency Department: Potential Role of CBC Parameters in COVID-19 Patients Whose PCR Tests Change from Negative to Positive

Introduction: The coronavirus disease-2019 (COVID-19) pandemic is an important health problem worldwide. In this study, we aimed to investigate the relationship between the clinical features and complete blood count (CBC) parameters of COVID-19 patients who were admitted to the emergency department (ED) and whose first polymerase chain reaction (PCR) test was negative and turned positive on the second admission. Methods: The study was designed as a single-center, retrospective, cross-sectional, and observational study. Demographic characteristics, vital signs, complaints, comorbidities, duration of complaints, time between two admissions, and defined CBC parameters in both the first and second admissions were recorded. Positive parameters were recorded in patients whose first PCR test was negative and turned positive and who were admitted to the ED again within ten days. The relationship between the PCR tests and these parameters was investigated. Results: A total of 123 patients were included in the study at the first admission, 89 of them were symptomatic. Of these, in the symptomatic group, body temperature was found higher and peripheral oxygen saturation percentage was found lower. Hypertension was the most common comorbidity, followed by diabetes mellitus and coronary artery disease, respectively. The most common symptom was fever, followed by cough and pain. The median time between the two PCR tests was six days. The leukocyte count, neutrophil count, lymphocyte count, platelet count, and hematocrit decreased on the second admission, whereas the plateletlymphocyte ratio (PLR) increased. Conclusion: CBC parameters defined in repeated evaluations with suspicion of COVID-19 may support the predictions of a positive test. Regardless of symptoms, the increase in PLR and decrease in leukocyte count, neutrophil count, lymphocyte count, platelet count, and hematocrit should raise suspicion that the COVID-19 test, which was initially negative, may turn positive in the process.