Rheumatoid Arthritis and Pulmonary Abnormalities on Spirometry

Takeaway

• Rheumatoid arthritis (RA) was associated with an increased risk of restrictive and obstructive pattern pulmonary abnormalities on spirometry.
• The associations were not explained by smoking and existing chronic respiratory illness.

Why this matters

• Emerging evidence suggests that airways diseases may be common in patients with RA, independent of smoking.

Study design

• A cross-sectional study of 350,776 participants (2008 with RA and 348,768 control participants) from the UK Biobank who underwent spirometry.
• Co-primary outcomes: spirometric abnormalities (restrictive or obstructive pulmonary pattern).
• Secondary outcomes: continuous % predicted forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), FEV₁/FVC, forced expiratory flow at 25-75% (FEF_25-75%) and severity of patterns.
• Funding: None.

Key results

• After adjusting for confounders, including smoking, RA vs control group had an increased risk of (adjusted OR [aOR]; 95% CI):
  • restrictive pattern (1.36; 1.21-1.53); and
  • obstructive pattern (1.31; 1.16-1.47).
• These associations remained significant after further adjustment for known chronic respiratory illness (aOR; 95% CI):
  • restrictive pattern (1.36; 1.21-1.52); and
  • obstructive pattern (1.21; 1.07-1.37).
• RA vs control group had a significantly lower (β; 95% CI):
  • % predicted FEV₁ (−2.93; −3.63 to −2.24) and FVC (−2.08; −2.72 to −1.45);
  • FEV₁/FVC (−0.008; −0.010 to −0.005); and
  • FEF_25-75% (−4.79; −6.08 to −3.49).
• In terms of severity of patterns, RA vs control group had the strongest risk of (aOR; 95% CI):
  • severe restrictive pattern (1.86; 1.08-3.23); and
  • severe obstructive pattern (1.54; 1.10-2.16).

Limitations

• RA cases were identified using self-reported data and current treatment with RA-specific medications.
   

This clinical summary originally appeared on Univadis, part of the Medscape Professional Network.