Obesity, C-reactive protein (CRP), functional status, and extensive smoking are new risk factors for rheumatoid arthritis-associated interstitial lung disease (RA-ILD), according to a study in the Journal of Rheumatology.
In this nested case-control study, 84 incident RA-ILD cases and 233 matched controls on age, sex, RA duration, rheumatoid factor, and time from exposure assessment to RA-ILD, were included.
Obesity, high-positive CRP (≥10 mg/L), and poor functional status (MDHAQ ≥1) were associated with increased risk of RA-ILD (OR 2.42, 95% confidence interval [CI] 1.11-5.24 vs normal BMI; OR 2.61, 95% CI 1.21-5.64 vs CRP <3mg/L; OR 3.10, 95% CI 1.32-7.26 vs MDHAQ <0.2).
Compared to nonsmokers, smoking 30 pack-years or more was strongly associated with risk of RA-ILD.
For RA-ILD, lifestyle and clinical exposures had an area under the curve of 0.79 (95% CI 0.73-0.85).
The authors concluded that these risk factors may be helpful in risk assessment and prevention, but that the “overall ability to predict RA-ILD remains modest.”
Kronzer VL, Huang W, Dellaripa PF, et al. Lifestyle and clinical risk factors for incident rheumatoid arthritis-associated interstitial lung disease. J Rheumatol. 2020:jrheum.200863. DOI: 10.3899/jrheum.200863. Epub ahead of print. PMID: 33191286.