Rheumatoid arthritis tied to increased risk for asthma

Takeaway

• A population-based cohort study found a 23% increased risk for asthma in adults with rheumatoid arthritis (RA) compared with a control group without asthma (matched for age, sex, income, region of residence, and medical history).

Why this matters

• Asthma affects 4.3%-8.6% of adults globally.
• Study is one of the largest to date and controlled for more factors than previous analyses.

Study design

• Prospective cohort of 6695 patients with rheumatoid arthritis and matched control patients not diagnosed with RA (n=26,780) from the Korean Health Insurance Review and Assessment Service-National Sample Cohort, 2002-2013.
• Funding: National Research Foundation of Korea.

Key results

• RA group had 23% higher risk of asthma vs control participants (16.4% vs 13.0%; aHR, 1.23; P<.001).
• Subgroup analysis by age:
  • men aged <40 years vs control participants: HR, 1.50 (P=.063);
  • women aged <40 years vs controls: HR, 1.28 (P=.017);
  • men aged 40-59 years vs controls: HR, 2.21 (P<.001);
  • women aged 40-59 years vs controls: HR, 1.10 (P=.074);
  • men aged >60 years vs controls: HR, 1.46 (P=.007); and
  • women aged >60 years vs controls: HR, 1.16 (95% CI, 1.05-1.35).
• Subgroup analysis by treatment:
  • methotrexate: HR, 1.27 (P<.001);
  • leflunomide: HR, 1.23 (P=.033); and
  • other treatment: HR, 1.20 (P<.001).

Limitations

• Findings may be restricted to Korean ethnicity.
• Observational design.