Risk of interstitial lung disease in patients with newly diagnosed systemic autoimmune rheumatic disease: A nationwide, population-based cohort study
Introduction
Systemic autoimmune rheumatic diseases (SARDs) comprise a group of diseases which involve immune dysregulation and affect various organ systems. About 5% of the general population are affected by SARD [1], which may involve the respiratory system including the airways, pleura, parenchyma or vasculature. Interstitial lung disease (ILD) describes a subgroup of pulmonary disorders involving inflammation and fibrosis of the lung parenchyma, which result in thickening and distortion of the alveolar wall with consequent impairment of gas exchange. Rheumatoid arthritis (RA), systemic sclerosis (SSc), polymyositis (PM), dermatomyositis (DMtis), primary Sjögren's syndrome (pSS) and systemic lupus erythematosus (SLE) are SARDs which are frequently associated with ILD. However, ILD can be the predominant presentation in patients with clinical features that suggest autoimmune processes but do not meet the classification criteria for a particular SARD. Such cases are described as ‘interstitial pneumonia with autoimmune features’ according to the 2015 guidelines of the European Respiratory Society/American Thoracic Society. In patients with SARDs, comorbid ILD may be increase the economic burden, reduce the quality of life and increase the risks of morbidity and mortality [2], [3], [4], [5], [6], [7], [8], [9].
The prevalence of ILD among patients with various SARDs vary across the world, mainly because of differences in screening methods used for ILDs. Among patients with SARD-associated ILD, cohort studies from the United States and China have shown that RA and SSc are the two major groups of SARDs, followed by DMtis/PM, pSS and SLE [10,11]. A cross-sectional study using an European cohort across 11 countries revealed that 30% of patients inflammatory myositis had ILD [12]. Recently, the prevalence of ILD was around 50% in a Nationwide Norwegian SSc cohort [13]. However, very few studies have investigated the incidence of ILD in patients with a specific SARD [14], [15], [16], [17]. To the best of our knowledge, there have been no population-based epidemiologic studies concurrently estimating the incidence rates (IRs) of ILD among patients with various SARDs and examining the relative risks of ILD in patients with SARD compared with non-SARD individuals. Recently, the Taiwanese National Health Insurance Research Database (NHIRD) has assisted population-based, longitudinal epidemiologic studies. Therefore, the present study aimed to examine the risks of ILD among patients with various SARDs using the NHIRD.
Section snippets
Ethics statement
The present study was approved by the Institutional Review Board (IRB) of Taichung Veterans General Hospital (IRB number: CE17100B). The requirement for informed consent was waived because personal detailed was completely anonymised before analysis of data.
Study design
This investigation was a nationwide, population-based, matched cohort study.
Data source
The study included claims data from 1997 to 2013 extracted from the Taiwanese NHIRD. The National Health Insurance (NHI) was initiated in Taiwan in 1995, and is a
Baseline characteristics
In total, we identified 62,930 patients with SARD and 251,720 matched non-SARD individuals in our analysis. The flow chart of subject identification is shown in Fig. 1. The mean ± SD follow-up duration was 6.1 ± 3.5 years in the SARD group and 6.3 ± 3.5 years in the non-SARD group. Table 1 shows the demographic and clinical characteristics of the study subjects. The mean age and gender distribution were not significantly different between SARD and non-SARD groups. The most common SARD was RA,
Discussion
This investigation is the first to compare the incidences of ILD between patients who were newly diagnosed with various SARDs with non-SARD individuals using a nationwide, population-based database. We found that the risk of developing ILD is highest for patients with SSc, followed by patients with DMtis, PM, pSS, SLE and RA. Recently, Bergamasco et al. reviewed epidemiological data of SSc-associated ILD in European and North American populations [18]. The authors found that the prevalence of
Funding
This study did not receive any funding support.
Declaration of Competing Interest
None.
Acknowledgements
The study is based on data from the NHIRD provided by the National Health Insurance Administration and the Ministry of Health and Welfare and managed by the National Health Research Institutes. The interpretation and conclusions do not represent those of the National Health Insurance Administration, the Ministry of Health and Welfare or the National Health Research Institutes.
The authors would like to thank the Biostatistics Task Force of Taichung Veterans General Hospital, Taichung, Taiwan,
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2022, Handbook of Systemic Autoimmune DiseasesCitation Excerpt :In three international registries that have included a large number of SLE patients, the prevalence of ILD ranges from 0.4% in the LUMINA (for Lupus in Minorities: Nature vs. Nurture) cohort [9] to 1.4% in the GLADEL (Latin American Group for the Study of Lupus) cohort [10], and 2% in the RELESSER (Spanish Rheumatology Society SLE Registry) cohort [3]. Recently, two studies from Sweden and Taiwan reported that the incidence rates of ILD in patients with incident SLE compared with the general population were 3.1 per 1000 years and 120 per 105 years, respectively [11,12]. Results of a recent systematic review of the literature and meta-analysis indicated that late-onset SLE patients, defined as ≥50 years of age, are more likely than early-onset patients to develop pulmonary manifestations.
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These authors contributed equally.