By IDSE News Staff

Obesity and female sex are consistent determinants for symptoms persisting after COVID-19, according to data shared at ECCMID 2023: the European Congress of Clinical Microbiology & Infectious Diseases, held in Copenhagen, Denmark (abstract O0045).

Researchers in the Netherlands analyzed the immunologic, clinical and psychosocial consequences of SARS-CoV-2 infection in data from the RECoVERED study. In a prospective study beginning in May 2020, the researchers enrolled 349 participants with a median age of 51 years; 56% were male and 51% had been hospitalized for COVID-19. All participants had laboratory-confirmed SARS-CoV-2 infection.

During the first month of follow-up, participants underwent many structured interviews. They collected biological samples and physical measurements, as well as data about sociodemographic features. Participants completed online questionnaires about the presence of ongoing symptoms monthly from months 2 to 12 as well as months 18 and 24 after the onset of COVID-19. Participants also completed the Brief Illness Perception Questionnaire (B-IPQ) at months 1, 6 and 12 of follow-up.

The B-IPQ asks nine questions about illness perception, including expected treatment effect and the feeling of personal control over their illness. The tool has been used to quantify illness perception in other chronic conditions, such as heart failure and chronic obstructive pulmonary disease.

“The reason why we wanted to include the Brief Illness Perception Questionnaire was to explore the participants’ experience of their illness over time,” researcher Elke Wynberg, MBBS-MSc, a clinical research fellow at Amsterdam University Medical Centers and Public Health Service of Amsterdam (GGD Amsterdam), said during the presentation.

The most common symptom associated with post–acute sequelae of COVID-19, commonly known as long COVID, has consistently been shown to be fatigue, Dr. Wynberg noted.

However, although more than 50 different symptoms have been reported as part of long COVID, which is defined by the World Health Organization as having at least one persistent symptom for three months after infection that is not explained by an alternative cause. A research gap remains in how these symptoms progress over time.

“Therefore, using our prospective data, we wanted to identify longitudinal trajectories of long-COVID symptoms up to two years after infection. We also then wanted to examine the determinants of belonging to a given trajectory, and finally, we wanted to investigate the association between the symptom trajectories and the participants’ illness perception over time,” Dr. Wynberg said.

The researchers found approximately one in 10 of the study participants experienced six or more symptoms over the two-year period. Most participants had two to four symptoms over two years. Conversely, about 25% did not experience any symptoms associated with long COVID.

“And what we see with these trajectories is that there is actually very little fluctuation in the total mean number of persistent symptoms over time, which we found quite surprising,” Dr. Wynberg said.

But when the researchers modeled groups based on the trajectories of an individual’s symptoms, they observed substantial fluctuation over time in the presence of some symptoms. For example, 15% of the study’s participants experienced improvement in their fatigue over time. On the other hand, and more worryingly, about 25% reported an increase in fatigue over the two-year period.

“When we looked at the determinants associated with belonging to a given trajectory, we saw once again what has been previously shown in other studies, that [being] overweight and obesity and also female sex were associated with belonging to a trajectory with a higher number of long-COVID symptoms,” Dr. Wynberg said.

When analyzing the association between trajectories of the total number of persistent symptoms and illness perception over time, the authors found that participants reporting six or more symptoms did not seem to experience an improvement in their illness perception, whereas those with approximately four or fewer symptoms reported improvement. In addition, participants reporting a greater number of symptoms experienced a more negative illness perception over time.

“While we cannot include a causal relationship between the number of symptoms and illness perception, this association does suggest that the patient’s own perspective of their condition is an important component of the experience of persistent symptoms,” she said.

The most important take-home messages for clinicians, Dr. Wynberg concluded, is that obesity and female sex are consistently being shown to be determinants of long COVID. Moreover, it is important to recognize that the presence of individual symptoms may fluctuate over time, even if the total number of symptoms remains constant.