People with rheumatoid arthritis who smoke are four times more likely to have interstitial lung abnormalities (ILA), placing them at a significantly greater risk of death, new research shows.

According to the research team from Brigham and Women’s Hospital, Boston, the findings emphasise the importance of further screening and treatment strategies for preclinical ILD in RA.

The team looked at data [link here] from a prospective cohort of current and former smokers in the US-based COPDGene trial, which included non-Hispanic White or Black smokers (aged 45-80 years) with at least 10 pack-years of smoking history, from which they identified 83 RA cases and 8,725 non-RA comparators who were scanned for ILA.

They found that the incidence of subclinical ILA – as determined by chest high-resolution computed tomography (HRCT) – was 17% in people with RA and 5% in those without the condition.

Furthermore, this association persisted after adjusting for confounders such as smoking intensity and duration, genetic risk (via the MUC5B promoter variant rs35705950) and other lifestyle factors, with RA linked with a 4-fold higher odds of ILA (OR 4.76 95%CI 2.54 to 8.92).

Particularly strong link with fibrotic ILA

The team also showed a strong association with fibrotic ILA, which was found in 8.4% of RA patients compared to 1.1% of the control group (OR 9.26; 95%CI 3.82 to 22.44), according to the paper, published in the British Journal of Rheumatology.

The analysis also revealed that RA with ILA or indeterminate ILA was linked with higher all-cause mortality than non-RA without ILA (HR 3.16, 95%CI 2.11 to 4.74) and RA without ILA (HR 3.02, 95%CI 1.36 to 6.75), equating to a three-fold increased risk of death.

At 50%, the ten-year death rate was also much higher in people with RA and ILA or indeterminate ILA compared to RA patients without ILA (22.0%) and for controls without ILA (21.2%).

The study had key limitations, including that RA patients were identified through a mix of self-reporting and use of DMARDs, that researchers had limited information on RA covariates, and that the prevalence of RA in the COPDGene cohort was relatively low, at 0.8%.

Nevertheless, the authors stressed that the findings “suggest that interstitial lung abnormalities have important prognostic significance in RA patients and emphasise the urgent need for additional research investigating the screening, monitoring, and early treatment strategies for subclinical ILD in RA, especially in high-risk patients with significant smoking history”.

Professor Peter Nash, Director of the Rheumatology Research Unit on the Sunshine Coast, added in an editorial that “in the context of self-management, [the study] also reminds of the importance of lifestyle advice in our patients including smoking cessation where applicable, which can improve patient outcomes and response to treatment”.