Screening and follow-up of interstitial lung disease associated with rheumatoid arthritis (RA-ILD) is a challenge in clinical practice. In fact, the majority of RA-ILD patients are asymptomatic and optimal tools for early screening and regular follow-up are lacking. Furthermore, some patients may remain oligosymptomatic despite significant radiological abnormalities. In RA-ILD, usual interstitial pneumonia (UIP) is the most frequent radiological and pathological pattern, associated with a poor prognosis and a high risk to develop acute exacerbations and infections. If RA-ILD can be identified early, there may be an opportunity for an early treatment and close follow-up that might delay ILD progression and improve the long-term outcome. In connective tissue disease–associated interstitial lung disease (CTD-ILD), lung ultrasound (LUS) with the assessment of B-lines and serum Krebs von den Lungen-6 antigen (KL-6) has been recognized as sensitive biomarkers for the early detection of ILD. B-line number and serum KL-6 level were found to correlate with high-resolution computed tomography (HRCT), pulmonary function tests (PFTs), and other clinical parameters in systemic sclerosis–associated ILD (SSc-ILD). Recently, the significant correlation between B-lines and KL-6, two non-ionizing and non-invasive biomarkers, was demonstrated. Hence, the combined use of LUS and KL-6 to screen and follow up ILD in RA patients might be useful in clinical practice in addition to existing tools. Herein, we review relevant literature to support this concept, propose a preliminary screening algorithm, and present 2 cases where the algorithm was used.

中文翻译：

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肺部超声 B 线和血清 KL-6 在类风湿性关节炎患者筛查和随访中识别间质性肺疾病的作用：文献综述、初步算法建议和临床应用

与类风湿性关节炎相关的间质性肺病 (RA-ILD) 的筛查和随访是临床实践中的一个挑战。事实上，大多数 RA-ILD 患者是无症状的，缺乏早期筛查和定期随访的最佳工具。此外，尽管有明显的放射学异常，一些患者可能仍然没有症状。在 RA-ILD 中，普通间质性肺炎 (UIP) 是最常见的放射学和病理学模式，与预后不良和发生急性加重和感染的高风险有关。如果可以及早发现 RA-ILD，则可能有机会进行早期治疗和密切随访，从而延缓 ILD 进展并改善长期结果。在结缔组织病相关的间质性肺病 (CTD-ILD) 中，肺超声 (LUS) 评估 B 线和血清 Krebs von den Lungen-6 抗原 (KL-6) 已被公认为早期检测 ILD 的敏感生物标志物。发现 B 线数和血清 KL-6 水平与高分辨率计算机断层扫描 (HRCT)、肺功能测试 (PFT) 和系统性硬化症相关 ILD (SSc-ILD) 的其他临床参数相关。最近，证明了 B 系和 KL-6（两种非电离和非侵入性生物标志物）之间的显着相关性。因此，除了现有工具外，联合使用 LUS 和 KL-6 来筛查和随访 RA 患者的 ILD 可能在临床实践中有用。在此，我们回顾了支持这一概念的相关文献，提出了一种初步筛选算法，并介绍了使用该算法的 2 个案例。