Long COVID linked to increased sick leave rate

In a recent study published on medRxiv* preprint server, researchers in Denmark examined associations between coronavirus disease 2019 (COVID-19) and sick leave after acute infection.

Study: Covid-19 and post-acute work stoppage: a hybrid register and questionnaire study in the Danish adult population. Image Credit: OlivierLeMoal/Shutterstock.com

*Important Notice: medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be considered conclusive, guide clinical practice/health-related behaviors, or treated as established information.

Background

Long COVID is defined as the persistence of post-acute symptoms in people previously infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is estimated that up to 20% of those infected develop long-lasting COVID.

A previous study identified sick leave as a potential indicator of long covid symptoms in Denmark. Yet the extent to which these symptoms translate into work capacity is poorly defined.

About the study

In the present study, researchers assessed the associations between COVID-19 and sick leave following acute infection in the adult Danish population.

Data was used from the national EFTER-COVID (AFTER-COVID) survey, launched in August 2021, to assess public health during the COVID-19 pandemic, focusing on the long COVID.

Danish residents were invited to participate via a nationwide digital messaging system based on SARS-CoV-2 reverse transcription polymerase chain reaction (RT-PCR) test results in the Danish Microbiology Database.

Test-negative controls without a positive result in the database at any time prior to the survey were randomly selected. This analysis included participants who completed the survey nine months after their RT-PCR test. Survey data was integrated with registry data on age, gender, vaccination, COVID-19 test results, reinfections and comorbidities.

The questionnaire was designed to provide information on participants’ baseline characteristics and sick leave between the test and survey dates. The team obtained data on inpatient and outpatient diagnoses from the Danish National Patient Register (DNPR).

All participants were asked whether they had taken sick leave at the time of the test or after. Those who answered yes were asked to indicate the duration and whether the leave was part-time or full-time.

The prevalence of extensive full-time versus part-time sick leave, that is, full-time versus part-time sick leave for more than four weeks after infection, was compared between subjects. positive and negative on the test using risk differences.

Results

Overall, 106,917 of 294,035 guests responded to the survey nine months after COVID-19 testing. After exclusions, the study population comprised 88,818 participants, including 37,482 SARS-CoV-2 positive individuals. They were on average 45 years old; most participants (64.3%) were women.

Less than 1% have received at least one dose of the COVID-19 vaccine. About 16.6% of participants were obese. Depression, anxiety and high blood pressure were the other common pre-existing conditions. The prevalence of substantial sick leave was higher in subjects who tested positive at 4.5% compared to 1.4% in controls.

It was similar across all age groups in controls, but increased with age in infected participants. It should be noted that 21% of those who tested positive who took significant sick leave were diagnosed with long COVID, compared to 1.6% of those infected who did not take the leave. Infected people had a higher risk of taking substantial full-time sick leave than controls.

The risk difference was attenuated when substantial sick leave was increased and defined as at least six months. Risk differences were higher for women than for men and for people aged 50 or older than the general population. The highest risk differences were for people with fibromyalgia, common obstructive pulmonary disease (COPD) or other lung diseases, and diabetes.

Healthcare workers had a higher risk differently than the general population. Infected people were also more likely to take substantial part-time sick leave than controls.

However, the risk of a major part-time work stoppage was lower for people aged 50 or over than that associated with a major full-time work stoppage, but was similar to that of the general population.

conclusion

The team noted that people infected with SARS-CoV-2 had an increased risk of taking significant sick leave. More than a fifth of those infected also had a long COVID diagnosis. The main limitations of the study include self-report design and potential recall bias.

Additionally, the duration of sick leave was not solely attributable to long COVID, as the questionnaire captured sick leave status in general. Additionally, participation bias was also likely, as people in poor health or with symptoms expressed more interest in participating.

Taken together, the results suggest that among subjects infected with SARS-CoV-2, 33 more people out of 1,000 took significant sick leave between one and nine months after acute infection compared to controls. Women, the elderly and people with pre-existing conditions such as fibromyalgia, obesity and COPD were the most affected.

*Important Notice: medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be considered conclusive, guide clinical practice/health-related behaviors, or treated as established information.