Assessing disease activity in scleroderma-related interstitial lung disease: a review and practical guide to management

Systemic sclerosis (SSc) is a heterogeneous disease with a propensity to involve multiple organ systems. There is a significant proportion of these patients with interstitial lung disease (ILD) who are at risk of mortality and morbidity. There are limited available tools to assess the severity of parenchymal lung involvement and are subject to confounding factors, including the presence of pulmonary hypertension and concomitant smoking history. The diagnostic tools include careful clinical history, examination, thoracic imaging, and pulmonary function tests. One of the limitations of assessing disease severity in SSc-ILD is the lack of standardized definitions for disease activity and serum biomarkers to predict future progression. Although there has been significant progress in managing SSc-related ILD over the last couple of decades with a few randomized double-blind clinical trials assessing the role of immunosuppression (mainly Cyclophosphamide and Mycophenolate Mofetil), the efficacy of these therapies is at best modest and is associated with significant toxicities. Furthermore, Nintedanib has shown promise in reducing forced vital capacity decline in SSc-ILD and in progressive fibrotic-ILD of a range of etiologies. Data are emerging for therapies like Rituximab and Tocilizumab, and we are likely to see further evidence of similar drugs being efficacious in this disease cohort. A relatively simplified algorithm is proposed in this review to guide clinicians dealing with ILD and SSc. It is imperative that clinicians take a multi-disciplinary approach to managing this complex disease in a changing therapeutic landscape.