Smoking and Subclinical ILD in RA versus the Multi-Ethnic Study of Atherosclerosis.

Cheilonda Johnson,Eric A Hoffman,Joan Bathon,R Graham Barr,Sonye K Danoff,Jon T Giles,David Lederer,Lynn M Schnapp

doi:10.1371/journal.pone.0153024

Cheilonda Johnson, Eric A Hoffman + Show 6 more

Open Access

https://doi.org/10.1371/journal.pone.0153024

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Abstract

A population-based cohort showed an association between cigarette smoking and subclinical parenchymal lung disease defined as regions of increased computed tomography (CT) lung densitometry. This technique has not been applied to the rheumatoid arthritis (RA) population where associated ILD is highly prevalent. The association between cumulative cigarette smoking and volume of areas of high attenuation (HAA: >-600 and <-250 Hounsfield Units) on full inspiratory CT was compared in 172 RA participants and 3,969 controls in a general population sample. Multivariable regression models were used to adjust for demography, anthropometrics, percent emphysema, and CT parameters. The mean cumulative cigarette smoking exposure was 25 (IQR 10–42) and 15(IQR 5–31) pack-years for the RA and non-RA cohorts, respectively. Mean HAA was 153(±57) cm3 and 129(±50) cm3 in the RA and non-RA cohorts, respectively. Each 10 cigarette pack-year increment was associated with a higher HAA by 0.03% (95% CI, 0.007–0.05%) in RA patients and by 0.008% (95% CI, 0.003–0.01%) in those without RA (interaction p = 0.001). Cigarette smoking was associated with higher lung attenuation; with a magnitude of association more pronounced in those with RA than in the general population. These data suggest that cigarette smoking may be a more potent ILD risk factor for RA patients than in the general population.

Highlights

Interstitial lung disease (ILD) is an important extrarticular manifestation of rheumatoid arthritis(RA)[1]
Thirty-eight percent were on prednisone therapy, 87% were on non-biologic DMARDs, and 46% were on biologic DMARDs at the start of the study (Table 2)
Forty-one percent had respiratory symptoms with 8% showing a restrictive pattern on pulmonary function tests (PFT) and 17% a diffusing capacity impairment (Table 2)

Summary

Introduction

Interstitial lung disease (ILD) is an important extrarticular manifestation of rheumatoid arthritis(RA)[1]. Since its first description over six decades ago, RA-associated ILD (RA-ILD) remains a significant source of morbidity and mortality [1,2,3,4] This is due in part to poorly understood disease pathobiology and limited therapeutic options[1]. A large general population based study has shown that cumulative cigarette smoking is a risk factor for high attenuation lung lesions using CT densitometry that could represent preclinical interstitial lung disease [23]. This technique is highly reproducible and has been validated for quantifying the extent of lung parenchyma affected by lung injury, inflammation or fibrosis [23, 24].

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