The long-term consequences of Covid-19 infection are the subject of intensive study around the world. In the January issue of the Lancet journal, the results of a cohort study on a population of 1,733 patients treated for covid infection in medical hospitals in Wuhan Province and discharged between January 7, 2020 and May 29, 2020 are published. The main purpose of the study was to study the consequences of infection and their impact on health and quality of life. The cohort did not include discharged patients who could not be monitored or monitoring would be difficult due to various reasons (mental disorders, dementia, re-hospitalization, etc.).
All patients were interviewed using a series of questionnaires to assess the severity of symptoms and the quality of life associated with health, underwent a physical examination and a 6-minute walk test. All patients underwent blood tests. Patients were stratified into groups depending on the severity of the course of covid infection on a 7-categorical point scale during their stay in the hospital in groups 3, 4 and 5-6 degrees of severity. The scale included indicators of lung function, high-resolution chest CT and ultrasound examination. Patients receiving lopinavir therapy for SARS-CoV-2 (severe acute respiratory syndrome) were tested for antibodies to the coronavirus.
Study consequences of Covid-19
The average age of patients was 57 years, there were 897 men (52%). The average follow-up time after the onset of symptoms was 186 days. 6 months after discharge, 76% of patients reported at least one or more symptoms, the number of which was higher in women. The most common symptoms were fatigue and muscle weakness (63%, 1038 out of 1655) and sleep problems (26%, 437 out of 1655). 23% (367 out of 1617) of patients reported anxiety or depression. In the 6-minute walk test, values below the reference threshold were shown by 24% of patients with 3 degrees of severity of the disease, 22% of patients with 4 degrees of severity and 29% of patients with 5-6 degrees of severity. The percentage of patients with diffuse lung changes during follow-up was higher in the group of patients with the most severe course of the disease in the acute phase. These patients had a higher score according to the CT results at follow-up (consequences of Covid-19).
Reduced transparency of the pulmonary fields in the form of frosted glass and uneven lines, which were observed during the radiological imaging method during subsequent observation, were the most common signs of lung tissue damage. Characteristic diffuse lung changes were registered in 22% of patients with grade 3 severity, in 29% with grade 4 and in 56% of patients with grade 5-6 severity. The average score according to the CT results was 3.0 in the group of patients with grade 3 severity; 4 in the group of patients with grade 4 severity and 5.0 in the group of patients with grade 5-6 severity. In patients of 5-6 degrees of severity, the ratio of the chances of detecting diffuse lung changes in comparison with the group of patients with 3 degrees of severity was 4.6 (95%), and in patients of the group of 4 degrees of severity – 1.61 (95%). A similar correlation was observed with respect to anxiety and depression, as well as fatigue and muscle weakness: in the group of the most severe course of the disease, compared with patients of the group of the most mild severity, they were 95% and 2.69, respectively.
The titers of neutralizing antibodies at the subsequent observation were significantly lower in comparison with the acute phase. The damage to the kidneys was indicated by the negative dynamics of the estimated glomerular filtration rate, which was at the level of 90 ml or more in 107 out of 822 patients without acute kidney damage in the acute phase of the disease, and at a control examination after 6 months it was below 90 ml. Antibodies were detected in 94 patients at a control examination after 6 months, but the seropositivity and median titer of neutralizing antibodies were significantly lower compared to the acute phase of the disease: 96.2% vs. 58.5% and 19.0 vs. 10.0, respectively. A decrease in neutralizing antibodies indicates a risk of re-infection with the Covid-2 virus.
The results of this study showed that in patients with the most severe course of the disease in the acute phase, more serious diffuse damage to the lung tissue persisted in the long term, which were easily detected by radiological methods. Examination of patients after 6 months allows screening patients who are particularly in need of long-term rehabilitation and control of the risk of re-infection with SARS-CoV-2.