- Design
- Retrospective matched cohort from a national US database
- Population
- 187,106 adults with first SARS-CoV-2 infection, with and without autoimmune rheumatic disease
- Primary outcome
- Long COVID diagnosis 28–365 days after infection
- Effect
- 2.8% vs 1.5%; adjusted HR 1.56 (95% CI 1.45 to 1.67)
Using the US National COVID Cohort Collaborative, researchers matched 187,106 adults with a first SARS-CoV-2 infection between 2021 and 2023, comparing those with autoimmune rheumatic disease with matched controls. Long COVID was defined by a diagnostic code or a long COVID clinic visit.
Long COVID was recorded in 2.8% of patients with rheumatic disease and 1.5% of controls (adjusted HR 1.56, 95% CI 1.45 to 1.67). Within the rheumatic disease group, severe acute illness, lung disease, obesity, and prior rituximab or glucocorticoid use were associated with higher risk. Sjögren's disease carried a higher risk than other conditions.
Coded diagnoses undercount long COVID and may be applied more readily to patients who already see specialists, so the true difference is uncertain. Fatigue and pain from the underlying disease also overlap with long COVID symptoms.
For clinicians, it is a reminder to ask about persistent symptoms after infection, and to weigh rituximab and steroid exposure when counselling about COVID-19 risk.
- Ask patients with rheumatic disease about persistent symptoms after a COVID-19 infection
- Keep glucocorticoid doses as low as possible
- Counsel patients on rituximab about their higher risk of complicated COVID-19
- Keep COVID-19 vaccination current in patients on immunomodulatory therapy
Why it matters
It identifies a group at higher risk of lasting symptoms that overlap with their underlying disease.
Don't overread it
Long COVID was defined from billing codes, which may be applied unevenly between groups.
The statistics, in plain English
A hazard ratio of 1.56 means about 56% higher risk, but in absolute terms the difference is 2.8% against 1.5%. Because long COVID was identified from coding, differences in how often it was diagnosed could account for some of the gap.
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