E064 Identifying patients with pulmonary disease in a mixed connective tissue disease cohort

Abstract Background/Aims Respiratory involvement specifically interstitial lung disease (ILD) is a recognised complication of mixed connective tissue disease (MCTD), with a reported prevalence ranging from 40-78%. Surveillance for ILD in other connective tissue diseases such as systemic sclerosis is established clinical practice. Using guidelines recently published by the American College of Rheumatology (2023) we undertook a service evaluation to evaluate current practice for patients in our centre. Methods Electronic case notes were searched using key terms ‘mixed connective tissue disease’, ‘MCTD’ and ‘anti-RNP positive’ to identify patients seen between January 2021-2023. Patients identified were then compared against three MCTD classification criteria (Sharp et al, Alarcon-Sergovia et al and Kasukawa et al). To ensure a robust diagnosis, only those meeting the classification threshold on two or more criterion were included. Results 56 patients were identified however only 44 met two classification criteria and were subsequently included. Mean age was 47.3 years with 40/44 (91%) female. 28/44 (64%) had previous CT chest imaging. In the remaining 16/44 (46%), none had reported symptoms suggestive of ILD in preceding two years. 34/44 (77%) patients had previous pulmonary function testing. In those without, 1/10 had recently reported dyspnoea. 9/44 (20%) had identified MCTD-ILD of which 7/9 (30%) were on immunosuppression, 3/9 for predominant lung disease. Of those with ILD, 7/9 (78%) had had PFTs in the last year. No patients with ILD had undergone assessment for ambulatory desaturation. 7/9 (78%) patients with ILD had received specialist respiratory input, 1 had been seen in a general respiratory clinic, and in 1 case it was unknown. All patients with identified ILD who met established criteria for treatment were receiving immunosuppression. No patient met criteria for progressive fibrotic ILD. No specific disease characteristics (utilising clinical criterion from classification criteria) were demonstrated to have association with ILD (statistical analysis performed using the chi-squared test). No association was demonstrated in patients displaying anti- Ro52 and Ro60 positivity and ILD. Conclusion This evaluation has highlighted that patients with identified MCTD-ILD are being treated and monitored well. However further surveillance for pulmonary involvement both at baseline and then subsequent interval pulmonary function testing needs to improve. This may account for the lower prevalence of ILD in our MCTD cohort in comparison to the literature. Surveillance of pulmonary involvement should take place regardless of clinical disease manifestations displayed. We need to establish feasibility for ambulatory desaturation testing in those with ILD within our outpatient setting. With increasing immunomodulatory treatment available identifying patients with MCTD-ILD is imperative. Disclosure R. Benson: None. K. Mashida: None. M. Ahmad: None. L.G. Spencer: None. Z. McLaren: None. T. Barnes: None.