New data reveals the real risk of long covid in patients with rheumatic diseases.
An international survey of rheumatology patients has found that about one in four infected with covid suffered symptoms for more than 28 days, and one in 10 experienced symptoms for 90 days or longer.
However, the good news is that many patients recover within the first two weeks, and long covid incidence rates appear to be lower among those who caught the virus more recently.
At the study outset, the authors hypothesised that people with systemic autoimmune rheumatic diseases may be more susceptible than the general population to prolonged covid symptoms, based on observed prolonged viral shedding.
They suggested potential reasons for extended symptoms include longer duration of infection, altered immunity, the use of immunosuppressants and rheumatic disease flares occurring at the same time as covid symptoms.
The data was collected in a COVID-19 Global Rheumatology Alliance (GRA) survey among systemic rheumatic disease patients who had received at least one covid vaccine dose. The survey took place from April to October 2021, and the GRA received around 11,000 responses, mostly from North America and the UK/Europe.
The current analysis included 441 respondents who reported test-confirmed covid infection with at least 28 days of follow up and was published in RMD Open.
The median reported symptom duration was 15 days, which appears to be similar to the general population.
A total of 107 people (24.2%) experienced symptoms lasting at least 28 days, thereby meeting the CDC definition of long covid. Among patients with sufficient follow-up, 42 (9.8%) met criteria for the WHO definition of long covid, which is 90 days or longer.
In addition to symptom duration and the proportion of patients with prolonged symptom duration, the authors also investigated baseline predictors of long covid.
Compared with people who didn’t report prolonged symptoms, those who experienced long covid tended to be older. After adjusting for age, those who were hospitalised with covid or who’d suffered more severe symptoms, including difficulties performing everyday activities, had more comorbidities or had osteoarthritis were also at increased risk of long covid.
Conversely, patients who contracted covid in 2021 were less likely to report long covid than those who’d caught it in the first half of 2020. This likely reflects the availability of vaccines or better acute covid management, or possibly the effects of different covid variants in circulation.
Estimates of long covid in the general population vary widely. Australian health economists say between 5% and 10% of people who get covid progress to long covid. However, Australia was largely shielded from earlier variants and many people were at least partly vaccinated when the Delta and Omicron surges occurred.
Globally, the statistics are all over the shop because of different study designs, a lack of definitive criteria for long covid and different kinds of health records being used, as well as vastly different covid experiences.
Professor Martin Hensher, of the Menzies Institute for Medical Research at the University of Tasmania, said that based on UK data, “maybe about 10% of people who’ve had a covid infection might still be experiencing long covid at three months.”
On the other hand, ongoing CDC surveys in the US have reported that among people who’ve ever had covid, around one in three experienced covid symptoms that lasted three months or longer.
It’s reassuring that the numbers reported in the GRA survey are at the lower end of this range.
Study strengths included the large sample size and the international nature of the study. Limitations include potential self-selection of healthier patients completing the survey, the possibility of inaccurate reporting or recall bias, the lack of data on specific symptoms and the lack of a general population comparator group.
“Prospective studies are needed to investigate symptom duration after breakthrough infection, among those on specific immunosuppressive therapies and in contemporaneous settings, related to treatment and viral variants,” noted the authors.
Commenting on the study, co-author Dr Jeffrey Sparks also suggested future studies need to sort out which symptoms are long covid symptoms, rather than rheumatic disease flares, organ damage or other unrelated symptoms.
