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Introduction Interstitial lung disease (ILD) is associated with increased mortality and significant morbidity in systemic sclerosis (SSc) patients. The recent ERS/EULAR guidelines recommend both mycophenolate mofetil (MMF) and rituximab (RTX) for SSc-ILD and suggest to use a combination of immunosuppressive therapies in high-risk patients. In this study, we used the EUSTAR database to retrospectively assess lung function outcomes in patients with SSc-ILD treated with RTX alone, MMF alone, or upfront combination therapy (MMF + RTX).Material and Methods We included SSc patients meeting the 2013 ACR/EULAR criteria, with ILD confirmed by chest HRCT and available % predicted FVC (%pFVC) at baseline and at follow-up closest to 12 months. Patients were grouped based on treatment initiated at baseline: (a) MMF alone, (b) RTX alone, or (c) upfront combination therapy. Patients on nintedanib or tocilizumab were excluded.Inverse probability of treatment weighting (IPTW) was used to adjust for confounding and treatment imbalances, following multiple imputation for missing data. The propensity score model incorporated the following variables: age, gender, disease subset (diffuse vs. limited), autoantibody status (ATA positivity), C-reactive protein. Linear mixed-effects models were used to compare the change in %pFVC and %pDLCO at follow-up across groups, adjusted for baseline values.Results A total of 535 patients were included: 346 on MMF, 168 on RTX and 21 on combination therapy. Patients baseline characteristics are summarized in the table 1.After a median follow-up of 13 months (IQR 11-17), %pFVC remained stable in all treatment groups. After IPTW, the average treatment effect (ATE) for %pFVC was 0.50 (95%CI -2.51, 3.50) for MMF vs combination and -1.24 (95%CI -4.31, 1.83) for RTX vs combination. For %pDLCO, ATE was 0.07 (95%CI -3.59, 3.74) for MMF vs combination and -0.76 (95%CI -4.49, 2.97) for RTX vs combination.Conclusions In this EUSTAR cohort analysis, treatment of SSc-ILD patients with MMF, RTA or upfront combination therapy were equally effective in slowing the decline of %pFVC. Further studies are required to better understand the role of combination of immunosuppressive therapies in SSc-ILD.Abstract P.120 Table 1Baseline characteristics and lung function of included patients