Work Strain Intensifies Inflammation in ACPA-Positive Rheumatoid Arthritis

New cohort data suggest physical job demands may worsen early joint inflammation in antibody-positive disease but effects ease with treatment.

Topline

Among people newly diagnosed with rheumatoid arthritis, higher work-related physical strain was linked to more severe joint inflammation at diagnosis only in those with anti-citrullinated protein antibodies. This association weakened after disease-modifying treatment began, highlighting an early window where mechanical stress may matter most.

Study Details

Rheumatoid arthritis is a chronic autoimmune disease marked by joint inflammation, pain, and long-term disability. Anti-citrullinated protein antibodies identify a biologically distinct form of the disease that is often more aggressive. Researchers from Leiden University Medical Center examined whether physical demands at work influence how severe joint inflammation is at the time of diagnosis and whether this differs by antibody status.

The study followed 417 patients with recent-onset rheumatoid arthritis treated at a Dutch tertiary center between 2010 and 2020. About half were ACPA-positive and half were ACPA-negative, allowing a direct comparison between these two groups.

Methodology

Investigators used an observational cohort design.
Work-related physical strain was estimated using standardized job exposure classifications and expressed as the percentage of time involving heavy lifting.
Joint inflammation was assessed at diagnosis using two approaches:
• Clinical examination with a 44-joint swollen joint count
• MRI imaging of the hands and forefeet to quantify inflammation such as synovitis and bone marrow edema

Patients were followed at regular intervals for up to five years after starting disease-modifying antirheumatic drugs.

Key Findings

• In ACPA-positive rheumatoid arthritis, every 10 percent increase in work-related physical strain was associated with about 7 percent more swollen joints at diagnosis, mainly in the hands.

• The same increase in strain was linked to roughly 5 percent higher MRI-detected joint inflammation, driven largely by bone marrow inflammation.

• After treatment with disease-modifying drugs began, the association between work strain and joint swelling weakened and was no longer observed over long-term follow-up.

• In ACPA-negative rheumatoid arthritis, work-related physical strain showed no meaningful association with joint swelling or MRI inflammation.

Implications for Practice

For patients, these findings suggest that physically demanding work may worsen joint inflammation at the earliest stage of antibody-positive rheumatoid arthritis, before treatment is established. This does not mean people should stop working or change careers, but it may explain why symptoms feel more severe at diagnosis for some individuals.

For clinicians, the results reinforce the importance of early diagnosis and rapid initiation of effective therapy in ACPA-positive disease. They also highlight a role for occupational therapy and workplace adaptations early in the disease course, especially for patients with physically demanding jobs. Addressing mechanical stress may help reduce symptom burden while medical treatment takes effect.