Does RA influence the development of lung diseases?

This study investigated the relationship between the diagnosis of rheumatoid arthritis (RA) and the development of lung diseases (LDs) over five years. 

The study showed that the markers of RA activity were associated with the development of lung disease.

LDs such as interstitial lung disease (ILD) commonly appear in patients with RA. They can lead to severe complications and, in some cases, even death. Over the course of an LD, the lung tissue can develop into scar tissue (fibrosis). Fibrosis makes the lungs stiffer, which heavily impacts the lungs' function and, eventually, the patients’ quality of life. 

In the early stages of LD, the symptoms (clinical appearance) might not be obvious. Other tests can indicate the onset of an LD. Certain blood measures can indicate inflammation, like the C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). The higher the CRP value and the quicker the red blood cells' settling time in a sample (higher ESR), the higher the level of inflammation. Testing the molecule transfer capacity from the smallest part of the lungs into the bloodstream with a DCLO-test (diffusing capacity of carbon monoxide) can give information about the lungs' state. 

It is also important to track the state of the RA itself. The measurement of DAS28 (Disease Activity Score of 28 joints) can determine how severe the RA has affected each patient's function. The value of rheumatoid factor (RF) in the blood might also give information about the state of the disease.

The treatment of RA usually includes drugs to lower inflammation and the resulting symptoms. If there is a relationship between the diagnosis and treatment of RA and the development of an LD is not yet known. 

This study observed 32 patients for five years. All 32 had recently been diagnosed with RA and did not show any lung-related symptoms. The authors measured lifestyle habits such as smoking. They also evaluated clinical appearance, blood measures like CRP, ESR, and RF. They included the results of digital imaging, DCLO, and DAS28 in their evaluation. The measures were taken shortly after the diagnosis of RA and at the end of the study.

The drugs prescribed to the patients by doctors included disease-modifying anti-rheumatic drugs (DMARDs). The most commonly used DMARD was methotrexate (MTX; Otrexup).

After the 5-year period, 40.63% (13 patients) presented symptoms related to the lung. Of these, 23.08% (3 patients) had developed ILD. 

Decreasing DCLO in the lung was significantly related to rising inflammation indicators (higher CRP and higher ESR-time). Smoking habits and MTX use were not related to the progression of LD. 

The authors concluded that there is a significant relationship between RA markers and the development of LD. They recommend starting monitoring indicators of LDs already in the early stages of RA.

This study included only a small number of patients. ESR and RF can be uncertain measures because of their risk for error.

Ask your doctor about the risks and identification of developing an LD.