Rheumatoid Arthritis Linked to Risk of ILD, Further Increased by Comorbidities: Study
UK: Researchers have found in a new study that patients with rheumatoid arthritis have an elevated risk of interstitial lung disease, which is further increased by coexisting comorbidities. The retrospective study showed that general comorbidity tools, such as the Charlson index, were limited in their ability to predict ILD risk, whereas a rheumatology-specific comorbidity assessment provided better risk stratification, potentially aiding earlier monitoring and preventive care.
The findings, published in Rheumatology, come from a retrospective analysis led by Amanda Busby from the Centre for Health Services and Clinical Research, University of Hertfordshire, Hatfield, and colleagues. The investigators examined how different methods of measuring comorbidity burden influenced the identification of ILD risk in people newly diagnosed with rheumatoid arthritis (RA).
Data were drawn from two consecutive multicentre, prospective RA inception cohorts in the UK. The study included 2,701 patients with newly diagnosed RA who were followed for a median of six years. Baseline information covered sociodemographic characteristics, disease features, treatments, laboratory findings, and functional status. Comorbidity burden was assessed using three approaches: a simple count of major comorbidities, the Charlson Comorbidity Index (CCI), and the Rheumatic Disease Comorbidity Index (RDCI), which is tailored to patients with rheumatic conditions.
The study led to the following findings:
- During follow-up, 101 patients (3.7%) developed interstitial lung disease (ILD).
- Of these, 12 had ILD at the time of rheumatoid arthritis (RA) diagnosis, 46 were diagnosed during follow-up, and 43 cases were identified through death certificates.
- Older age at RA onset was associated with a higher risk of ILD (adjusted odds ratio [aOR] 1.03 per year increase).
- Seropositive patients had more than twice the risk of ILD compared with seronegative patients (aOR 2.58).
- Individuals with a history of smoking had a 70% higher risk of developing ILD (aOR 1.70).
- A greater burden of lung-related comorbidities measured using the Rheumatic Disease Comorbidity Index (RDCI) was strongly associated with ILD development (aOR 4.59).
- The overall RDCI score was also significantly associated with ILD risk (aOR 1.32).
- Comparable associations were not consistently observed when comorbidity burden was assessed using the Charlson Comorbidity Index or simple comorbidity counts.
The researchers concluded that the choice of a comorbidity assessment tool can alter the ability to detect patients at risk of ILD. A disease-specific index such as the RDCI appears to identify clinically relevant associations that broader, generic tools may overlook.
The findings suggest that baseline lung comorbidities should be recognized as an additional risk factor for ILD in RA. Incorporating rheumatology-focused comorbidity measures into routine assessment may help clinicians better identify high-risk patients, enabling more targeted screening and earlier intervention to mitigate serious pulmonary complications.
Reference:
Dacheva, R., Busby, A., Kiely, P., Young, A., Walsh, D. A., McWilliams, D. F., Galloway, J., & Nikiphorou, E. Rheumatoid arthritis and interstitial lung disease: The role of comorbidities. Retrospective analysis of two RA inception cohorts in the UK. Rheumatology. https://doi.org/10.1093/rheumatology/keag089
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