MILAN – Patients with psoriatic arthritis (PsA) who are using biologic and targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs) have fivefold higher risk for interstitial lung disease (ILD) than does the general population, according to the first study to explore risk of ILD in this particular patient group.
The study also found 10-fold higher risk of ILD in patients with RA who were starting a b/tsDMARD, compared with the general population, while the addition of methotrexate did not appear to be associated with increased risk for ILD in either RA nor PsA.
Sella Aarrestad Provan, MD, of the Center for Treatment of Rheumatic and Musculoskeletal Diseases at Diakonhjemmet Hospital, Oslo, presented the results at the annual European Congress of Rheumatology.
Explaining the motivation for the study, Dr. Aarrestad Provan said that, in RA, methotrexate’s role in ILD development remained unclear, while some small studies linked b/tsDMARDs with risk for ILD. “In PsA, very few studies have explored the risk of ILD, and no systematic studies have looked at ILD risk factors in this disease.”
The researchers analyzed patient data from hospital and death registries across five Nordic countries (Denmark, Norway, Finland, Iceland, and Sweden) and compared them with general population controls. They calculated risk ratios for people who developed ILD within 5 years of starting a b/tsDMARD (with or without methotrexate).
A total of 37,010 patients with RA, 12,341 with PsA, and 569,451 members of the general population were included in the analysis, with respective disease durations of 10 and 8.9 years. Methotrexate was used along with b/tsDMARDs in 49% of patients with RA and 41% with PsA, and most patients were already on methotrexate when b/tsDMARDs were started. The tumor necrosis factor inhibitor etanercept (Enbrel) was the most commonly used b/tsDMARD in both RA and PsA, followed by infliximab (Remicade and biosimilars) and adalimumab (Humira and biosimilars).
The incidence of ILD within 5 years of starting a b/tsDMARD was 0.8% in patients with RA, 0.2% with PsA, and 0.1% in the general population, and these findings generated hazard ratios of 10.1 (95% confidence interval, 8.6-11.9) for RA and 5.0 (95% CI, 3.4-7.4) for PsA, compared with the general population as reference.
When the risk for ILD was explored according to methotrexate use in RA patients, “there was no signal of increased risk across patients using methotrexate,” Dr. Aarrestad Provan reported. When risk of ILD was explored according to b/tsDMARD use in RA patients, a signal of increased risk was observed with rituximab, she noted, “but upon adjusting for age, sex, and comorbidities, this association was no longer significant, but was still numerically increased.”
Iain McInnes, MD, PhD, vice principal, professor of rheumatology, and head of the College of Medical, Veterinary and Life Sciences at the University of Glasgow, remarked that he “loves results that are unexpected” and thanked the researcher for such an “important study.”
“For years, we’ve been interested in the potential for DMARDs to impact interstitial lung disease, with potential that drugs could make it worse, or better,” he said. “This study is wonderful and novel because first of all, there hasn’t, until now, been a direct comparison between RA and PsA in quite this way, and secondly, we haven’t really assessed whether there is a drug-related risk in PsA. Note that drug related does not necessarily imply causality.”
Regarding mechanisms, Dr. McInnes added that “epidemiologic studies suggest that PsA often coexists with the presence of cardiometabolic syndrome and obesity, which has a higher prevalence in PsA than in RA. Obesity is also related to ILD. As such, it begs the question of whether cardiometabolic, diabetes, or obesity-related features may give us a clue as to what is going on in these PsA patients.”
The research was supported by NordForsk and FOREUM. Dr. Aarrestad Provan reported serving as a consultant to Boehringer Ingelheim and Novartis and receiving grant/research support from Boehringer Ingelheim. Dr. McInnes declared no disclosures relevant to this study.
This article originally appeared on MDedge.com, part of the Medscape Professional Network.
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