Researchers in Spain have discovered that patients who have so-called long COVID two years after their initial infection are more likely to have symptoms if they were not hospitalized after contracting the disease than those who were hospitalized.
In research published Tuesday in Infectious Diseases, the Spanish researchers reported in their cross-sectional study that the percentage of patients with at least one post–COVID-19 symptom two years after acute infection was 59.7% for hospitalized patients; that number increased to 67.5% for those who had not required hospitalization.
These results suggest that patients who were not initially hospitalized are at risk of suffering from long COVID just as much, if not more so, than those who required hospitalization initially.
“Current evidence supports that long COVID will require specific management attention independently of whether the patient has been hospitalized or not,” the researchers concluded in their report.
The researchers believe this work represents the first study to compare the presence of post–COVID-19 symptoms between hospitalized and nonhospitalized patients two years after the infection.
The study also revealed that long COVID patients who had been hospitalized were more likely to have suffered from dyspnea (shortness of breath) in their initial infection, whereas anosmia (loss of smell) was more prevalent among nonhospitalized patients.
Despite these initial different symptoms, both hospitalized and nonhospitalized patients suffered from similar symptoms post-COVID.
Overall, small differences in COVID-19 onset symptoms without differences in post–COVID-19 symptoms were found among hospitalized and nonhospitalized COVID-19 survivors, reinforcing the hypothesis that post–COVID-19 symptoms are not correlated solely with COVID-19 severity.
The study included a group of individuals hospitalized due to SARS-CoV-2 infection from two urban hospitals and a group of patients infected with SARS-CoV-2 not needing hospitalization who were managed in an outpatient setting by their general practitioners in Spain.
All hospitalized and nonhospitalized patients with COVID-19 who were managed at all of the participating centers during the first wave of the pandemic were included in an anonymous database; 400 patients each from both hospitalized and nonhospitalized groups were then randomly selected using randomization software.
Of the 400 hospitalized patients and the 400 nonhospitalized patients randomly selected, 360 hospitalized patients and 308 nonhospitalized patients participated.
The study only looked at patients with COVID-19 who had been infected with the Wuhan variant and not reinfected. This is a critical point, since current data about post–COVID-19 symptoms and SARS-CoV-2 variants of concern suggest that the Alpha and Delta variants overall exhibit less severe post–COVID-19 symptoms than the Wuhan variant. Studies have indicated that the Omicron variant also produced less prolonged symptoms than the Delta variant.
Additionally, the study did not take into consideration vaccination status. However, the researchers did note that most patients reported that they had received two doses of vaccine without experiencing a significant change in their symptoms.
Another limitation of the study was that post–COVID-19 symptoms were self-reported by patients in telephone interviews. This could lead to potential recall bias; it is possible that the use of scales evaluating different symptoms (such as dyspnea and anosmia) could reveal potential differences between groups.