and indirectly with mosaicism and air trapping on expiratory imaging). Similar to RA-ILD, a subset of patients will have evidence of RA-airways disease on diagnostic testing without accompanying symptoms. Symptoms can range from a mild cough or wheeze with activity to profound exertional breathlessness, depending on the type of airway involvement. The presence of airway disease can lead to increased morbidity and even mortality [113, 118]. A study comparing mortality in RA patients with and without obstructive lung disease found a doubling in the risk of death in those with obstructive lung disease [113].

Subtypes or RA-AD

Obliterative Bronchiolitis

Obliterative bronchiolitis (OB) is a form of airway disease affecting the small airways (de ned as airways ≤2 mm in diameter). Though rst described in 1977 in six subjects ( ve of whom had RA [119]), there is a paucity of literature to guide clinicians in diagnosis and management. OB (also referred to as constrictive bronchiolitis) is identi ed by concentric narrowing of membranous and respiratory bronchioles caused by peribronchiolar infammation and brosis without evidence of lymphoid hyperplasia [120]. RA has the highest incidence of bronchiolitis among the CTDs [121] though the cause is unknown and true estimates of prevalence are lacking. Studies looking at centrilobular nodules as a marker of bronchiolitis nd these changes in 6% of patients [110, 122]. It is reported to be more common in women [123–126] and some case series report long-standing RA as a risk factor [124, 127]. Patients present with a nonspeci c symptom complex of either abrupt or gradual onset of breathlessness and can have an accompanying cough with or without sputum production. Exam reveals squeaks and crackles on auscultation. HRCT imaging shows mosaic perfusion with or without concomitant bronchiectasis and air trapping on expiratory imaging [128] and lavage shows increases in neutrophils [129]. Up to a third of patients can have concomitant ILD [123]. There are conficting results in the literature regarding prognosis. Older studies report declines often over months [119, 123, 127, 130–132]. In contrast, the largest case series of subjects with RA and OB found general stability with a slow decline in FEV1 over time and 27% all-cause mortality over a median follow-up of 5 years [124]. This stability over time was replicated in a study looking at all-comers with CTD-ILD (the majority of whom had RA) [121]. Female sex has been associated with better outcomes [121]. Treatment choices are based on case reports and anecdotal evidence and involve combinations of inhalers and systemic corticosteroids with or without other immunomodulatory agents. Corticosteroids are often tried

though their effect may be limited [123, 126, 127, 129]. Other agents have been used in case reports such as azathioprine [127], cyclophosphamide [125], macrolide antibiotics [124, 129, 133], and etanercept [134].

Bronchiectasis

Though studies have found widely variable rates of bronchial dilatation or bronchiectasis in RA ranging from 16% to 62% [114, 135, 136], many studies nd an overall prevalence around 30% [5, 29, 110, 122]. Bronchial dilatation is reported as one of the most common ndings in both early and late RA [117] and, though studies have found cases where bronchiectasis precedes RA, it may be more prevalent in long-­standing severe RA [137]. Recurrent infections and/or airway colonization likely play some role in its development in this population of patients treated with immunosuppression [138]. Secondary Sjögren in RA may also predispose to chronic or recurrent airway infection due to decreased and altered airway secretions. A higher prevalence of mutations in the cystic brosis transmembrane conductance regulator (CFTR) gene has been noted in RA patients with bronchiectasis [139]. While bronchiectasis is often found as an incidental nding on chest imaging, it can cause cough with sputum, hemoptysis, dyspnea, and recurrent infections when severe [137]. The presence of earlyonset bronchiectasis has been reported to increase mortality [140], up to vefold in one study compared to patients with RA alone [141], and higher than bronchiectasis of other etiologies [142]. Treatments are similar to bronchiectasis of other etiologies and include strict management of respiratory infection, sputum mobilization, and consideration of scheduled oral/inhaled antibiotics in severe cases with recurrent infections. Severe bronchiectasis with recurrent respiratory infection in RA can be a management challenge, requiring providers to balance the use of immunosuppressive agents to control synovitis versus the risk of recurrent respiratory infection.

COPD

Though the incidence and prevalence of COPD appears to be increased in RA [113, 143–149], many studies did not control for smoking [143–145], a risk factor for both RA and COPD. Utilizing the Nurse’s Health Study, investigators looked at 843 women with RA and a mean follow-up of 18.6 years and found that RA was associated with an increased risk for COPD after controlling for smoking (HR 1.68, 95% CI: 1.36–2.07) [148]. This increased risk in both smokers and non-smokers was also found in a popu- lation-based cohort study that included 603 RA patients from the Rochester Epidemiology Project [113]. These data suggest that RA patients may be more susceptible to the effects of tobacco smoke. Indeed there are possible