An observational study on effectiveness of azathioprine in treatment of interstitial lung disease secondary to connective tissue disease

Abstract

Azathioprine (AZA) is common treatment for connective tissue disease (CTD) related interstitial lung disease (ILD) which is reflected in the British Thoracic Society 2008 ILD guideline [1]. However, this is only a grade C evidence and no studies have reported the real-life effectives in this patient subgroup. An observational study of the effectiveness of AZA in CTD ILD was carried out by retrospective data collection of 30 patients seen in CTD – ILD clinic between January 2010 and December 2018. The mean age of patients was 62.79 (+/- 13 SD) years of which 16 (53%) were females with underlying CTDs (table 1). 16 (53%) patients continued AZA for a mean duration of 52 (+/- 18 SD) months. The FVC and DLCO were preserved in this group compared to those who did not [Mean FVC change: -1.630% (CI 0.95 = 0.284) vs -15.767% (CI 0.95 = 0.555), Mean DLCO change: -4.478% (CI 0.95 = 0.302) vs -14.233% (CI 0.95 = 0.689) respectively]. AZA was stopped in 16 patients due to toxicity (16%) or intolerability (27%). 2 were later re-started on AZA with good tolerance. Our single centre experience showed that FVC of patients with CTD related ILD, over a mean 50-month duration of therapy with of AZA, remained stable. This leads us to conclude that AZA is effective in treatment of CTD related ILD but prone to poor tolerability and systemic toxicity. Reference: [1] Wells AU, Hirani N. Interstitial lung disease guideline. Thorax. 2008 Sep 1;63(Suppl 5):v1-58.