OP0146 Idiopathic inflammatory myopathies & interstitial lung disease

Background

Idiopathic inflammatory myopathies (IIM) is associated with interstitial lung disease (ILD). IIM associated ILD ranges from subclinical disease, to rapidly progressive ILD (RPILD). Early recognition of these patients is essential for determining treatment.

Objectives

A retrospective case-control study in a tertiary referral centre to identify: a) Clinical features associated with ILD in IIM. b) Whether antibodies e.g. anti-ENA and myositis specific antibodies (MSA), may aid recognition of ILD or RPILD. c) Whether intensive immunosuppressants have implication on prognosis of ILD.

Methods

The clinical records of IIM patients who were followed up in rheumatology clinic or admitted into our hospital from Jan 2013 to Dec 2016 were reviewed. We analyse the clinical characteristics (rash, arthritis, myositis, Raynaud's phenomenon, mechanic hands, and cutaneous ulcers with blood tests), antibody profile (anti ENA: anti-Jo1, Ro, La, Sm, RNP, Scl 70 and MSA: anti OJ, EJ, PL7, PL12, SRP, PM-Scl75, PM-Scl100, Ku, SAE1, NXP2, TIF1γ, MDA5, Mi2), treatment and survival. We compare these parameters in IIM-ILD patients against those without ILD. Chi-squared and Mann-Whitney U tests were used to analyse categorical and continuous variables. Log rank test was used to compare survivals.

Results

Among the 101 IIM patients, the mean age was 62 years old with 71% female. 74 patients (73%) had dermatomyositis, 17 (17%) had polymyositis and 10 (10%) clinical amyopathic dermatomyositis. 53 patients (52%) had ILD; 48 (48%) had no ILD. In ILD group, 11/53 patients (21%) were RPILD. All patients had anti-ENA checked. 59/101 patients (58%) had MSA profile. Significantly more ILD patients had arthritis, mechanic hands, anti Jo1, anti Ro and anti MDA5 than those without ILD. 21/101 patients had cancers associated with IIM, but cancers were less common in ILD group. Subgroup analyses revealed arthritis, mechanic hands and anti MDA5 were again significantly more common in RPILD compared to other ILD patients (table 1). Anti MDA5 were more commonly found in deceased versus alive patients (40% vs 8.2%, p=0.02; OR=7.5). Deceased patients also had significantly higher median peak ferritin (2475 vs 553 pmol/L, p=0.008), so did the ILD group (2332 vs 484 pmol/L, p=0.02). ILD patients received more intensive immunosuppressants (high dose steroid, cyclophosphamide, MMF, tacrolimus, IVIg or even rituximab) than non ILD group. The survival was not significantly different between ILD and non ILD groups. However despite intensive immunosuppressants, RPILD patients' survival was still much worse than the other ILD patients (figure 1).

Conclusions

Certain clinical features and MSA aid recognition of IIM-ILD. Anti MDA5 is related to ILD, RPILD and mortality. Ferritin may be a disease activity and prognostic marker for IIM-ILD. With immunosuppressants, survival of IIM patients with or without ILD is similar. For RPILD patients, the survival is significantly worse despite active treatment.

References

[1] Satoh M, et al. Clin Rev Allergy Immunol2017Feb;52(1):1–19. [2] Xu Y, et al. Clin Rheumatol2016Jan;35(1):113–6. [3] Nakashima R, et al. Lupus2016Jul;25(8):925–33.

Disclosure of Interest

None declared