Prevalence of CTD-ILDs

Pulmonary fibrosis is a critical threat across a broad range of connective tissue disease-associated interstitial lung diseases (CTD-ILDs)1–5



ILDs make up a diverse group of more than 200 heterogeneous lung disorders, mostly classified as rare or only infrequently seen in clinical practice8–10

While some ILDs are idiopathic, others manifest as a result of environmental exposure to antigens or as a pulmonary complication of an underlying CTD11

In CTD-ILDs, pulmonary fibrosis is characterised by the often chronic and irreversible scarring of lung tissue,12,13 and is a key driver of irreversible lung damage and early mortality in CTDs.1–5,14

What is the prevalence of ILD in CTDs?

Prevalence estimates for different CTDs and CTD-ILDs vary between different studies. Prevalence figures shown below are based on a range of different estimates from different studies15–40

Prevalence of RA, SSc, primary Sjögren’s syndrome and PM/DM/CADM as CTDs and CTDs-ILDs per 100,000


Prevalence of CTDs and CTD-ILDs per 100,000.
Prevalence figures sourced as midpoint values from ranges for CTD and CTD-ILD prevalence as follows: RA prevalence 500–1000 per 100,000;15–17 RA-ILD prevalence 10%–30% of RA.18-22 SSc prevalence 7.2–44.3 per 100,000;23 SSc-ILD prevalence 42% of SSc.24 primary Sjögren’s syndrome prevalence 90–2700 per 100,000;25,26 primary Sjögren’s syndrome-ILD prevalence 8%–20% of primary Sjögren’s syndrome.27-30 PM/DM prevalence 5–22 per 100,000;31,32 PM/DM/CADM-ILD prevalence 20%–78% of PM/DM/CADM.33-40

Varying prevalence of ILD in diverse CTDs has led to different approaches to screening

CTD-ILDs are an important subgroup of ILDs10
CTD-ILDs a large / important subgroup of ILDs


* Not an estimated clinical diagnosis
† For example: asbestosis, silicosis.
Adapted from: Cottin V, et al. Eur Respir Rev. 2018;27:180076.


ILD occurs in 42%–50% of all SSc patients24,41


Find out more about the prevalence of SSc-ILD


ILD develops in up to 30% of patients with RA18-22


Find out more about the prevalence of RA-ILD


ILD develops in 8%–20% of patients with primary Sjögren’s syndrome27-30


Find out more about the prevalence of primary Sjögren’s syndrome-ILD



ILD often develops early in the course of a CTD, and may even be the first manifestation of a previously undiagnosed or unrecognized CTD.1,2,5,6 ILD in CTDs may be subclinical in nature (presenting without symptoms),7 be chronically progressive, or even present in a life-threatening manner.42

Acute exacerbation of ILD, characterized by rapid respiratory deterioration with severe hypoxemia, can occur in patients with CTD-ILDs at any point during the course of disease.43–47 Based on patients with IPF, acute exacerbation of ILD is most likely triggered by an acute event, such as infection.48 Post-exacerbation hospital mortality in patients with CTD-ILDs is reported to range from 50%–100%.43


See what Clive Kelly, Senior Lecturer, has to say about the prevalence of pulmonary fibrosis in patients with CTDs


We see a great many patients with connective tissue diseases who evolve pulmonary fibrosis, but the pattern is much different one disease to the other. For example, at one extreme we’ll see scleroderma, where up to 50% of patients may have interstitial lung disease by comparison with SLE where perhaps less than 5% do. In between that we see rheumatoid arthritis with something around 8% prevalence and Sjögren’s syndrome with a higher prevalence but rather less in the way of progression. So, it’s not just the prevalence that differs, but it’s the degree of progression that differs between each of these diseases. The commonalities would be male sex is something which we know is a major predictor for interstitial lung disease. Smoking, which is undoubtedly a big risk factor and the presence of various antibodies which differ depending on which specific connective tissue disease we are dealing with. So, the classic patient would be phenotypically a male smoker with positive antibodies.

What could fibrotic ILD mean for your patients with CTDs?

CTD, connective tissue disease; CTD-ILD, connective tissue disease-associated interstitial lung disease; IIP, idiopathic interstitial pneumonia; ILD, interstitial lung disease; HP, hypersensitivity pneumonitis; IPAF, interstitial pneumonitis with autoimmune features; IPF, idiopathic pulmonary fibrosis; LAM, lymphangioleiomyomatosis; LCH, Langerhans cell histiocytosis; NSIP, non-specific interstitial pneumonia; RA, rheumatoid arthritis; RA-ILD, rheumatoid arthritis-associated interstitial lung disease; SSc, systemic sclerosis; SSc-ILD, systemic sclerosis-associated interstitial lung disease.

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