In this third and final video, we will be reviewing the laboratory tests that are most helpful for monitoring the severity and progression disease as well as helpful imaging studies. And finally, we will review the different stages of COVID-19 and factors that are associated with a poor prognosis or outcome. Laboratory findings are nonspecific. However I have found three values to be particularly helpful in assessing the severity and prognosis of COVID-19. C reactive protein, abbreviated CRP is a measure the degree of inflammation, and is elevated in the majority of cases, a normal value is zero to five. More severe cases of COVID COVID-19 have levels of 100 to 400. And the higher the CRP, the higher the the likelihood of severe disease. D dimer is a reflection of abnormal clotting and is elevated in severe cases. A normal value is less than 0.5. A value of one to two point five is associated with approximately a three fold increase in clot formation in the veins or arteries. And a value of greater than two point five is associated with it six to seven fold increased risk of abnormal clotting. The lymphocyte count has been shown to be an important prognostic factor when it is under 800 or 0.8 thousand. The risk of poor of poor outcome increases. Here are the values for the patient I presented. Note the marked elevation of CRP, D dimer, and the decrease in lymphocyte count. Note how these parameters all improved after convalescent plasma was administered. At the time of the plasma administration, the lymphocyte count had dropped to zero point four eight. Subsequently rising to a normal value of one point one six. Here are two of our patients x rays on day one and day two. You can see the marked increase in lung opacification are wideout, consistent with the development of acute respiratory distress syndrome or a RDS? Checks a tray is abnormal in 60% of patients. Chest CT is a more sensitive Identifying abnormalities in 84% of cases. It should be emphasize that CT scan may identify abnormalities even in mild cases. In severe disease, 96% of the time abnormalities are identified. Here are two examples of ground glass appearance on. On the left is in one lung field. The arrow on the right is bilateral ground glass appearance. This is Is from the WHO and shows the verios levels of illness severity and potential outcome. Moderate and mild cases make up 80% of all cases, and mild cases rarely progress to death. Moderate disease and severe disease more commonly progress and patients who are critical, like our patient, have a high chance of dying 22-62%. Critically ill patients may develop septic shock with organ failure. History syndrome may be associated with high levels of Cydocine. Including interleukin six. As seen in the case I presented. The average duration of hospitalization and the who experience was 12 days. 11 days for non severe cases and 13 days for severe cases. Mechanical ventilation was required in 38% of severe cases. To assess what stage each patient is in, and to predict whether or not the patient will worsen. It is important to understand the timing of the different stages to disease. Whenever possible is important to estimate the time of exposure and know what day symptoms began. The usual incubation, incubation period after exposure is four to five days. During this period the patient has no symptoms. Onset of symptoms can take up to 14 days. Early on, the symptoms tend to be mild and 40%. Do not progress five to eight days after the onset of symptoms. 40% of patients experienced shortness of breath, indicating moderate disease. At eight to 12 days 15% of cases progressed to severe disease. These patients experienced a decrease in oxygen saturation below 93% and require oxygen administration. At 12 to 14 days 5% become critically ill and work are managing the IMICU and often require mechanical ventilation as described in our case. In the New England Journal of Medicine series, deaths occurred in 1.4% of cases with a 0.1% mortality for non severe cases and 8.1% for severe cases. The case fatality ratio reported by the WHO was 3.8% in China. Case fatality or CF is defined as the number of deaths per total number of patients with disease. This percentage may be an over estimate, because milder disease is not always recognized, lowering the denominator, the case face. Fatality rate will also be higher where care is limited, given these limitations experts estimate the case fatality rate is somewhere between 0.5 and 3.5%. To put this in perspective influenza case fatality rate is 0.1%, therefore the case fatality rate of COVID-19, is five to 35 times higher than seasonal influenza. Mortality is related to set the sex of the patient men having a higher mortality than women, as do patients with chronic illnesses, specifically hypertension, diabetes, cardiovascular disease, lung disease and cancer. Also patients with obesity and sickle cell disease have a worse outcomes. Mortality is also affected by age. Death is exceedingly rare below age Is 30 and begins to climb in those over a 60, being 4% for ages 60 to 70, 8% for ages 70 to 80 and 15 to 25% for those eight year old older. This series from New York City demonstrate even worse outcomes related age, with a very steep slope relating age to mortality beginning at age 50. Note that patients over 80 had a 60% mortality in the New York series. In summary, lab findings in this disease are nonspecific. CRP and D-dimer are helpful for assessing severity of disease, and a low lymphocyte count is associated with a poor outcome. Check x-ray has a low sensitivity, just CT scan being more sensitive, often showing ground glass opacification. 80% of the time the disease is mild to moderate in severity, but the disease can progress to irreversible hypoxia and death. Higher mortality is seen in men, those 60 years of age or older and those with underlying diseases. Overall mortality is 0.5 to 3.5%, that is 5 to 35 times more deadly than influenza.