Long-term evaluation of pulmonary function and survival of patients with interstitial pneumonia with autoimmune features.

OBJECTIVES: Interstitial pneumonia with autoimmune features (IPAF) includes patients with interstitial lung disease with autoimmune features who do not meet criteria for a connective tissue disease (CTD). Previous studies showed a wide variation in the radiologic pattern, pulmonary function and prognosis but there is still limited data on longitudinal outcomes. We aim to describe the long-term pulmonary function, radiological patterns, and survival of IPAF patients and explore a classification based on CTD-like subgroups by using clinical/serologic data. METHODS: Retrospective analysis of IPAF patients who were sub-classified into six CTD-(like) subgroups: systemic lupus erythematosus-like, rheumatoid arthritis-like, Sjögren's syndrome-like, scleroderma, myositis-like, and unclassifiable. Linear mixed-effect models were used to compare the change in percent-predicted forced vital capacity (FVC%), percent-predicted diffusion capacity (DLCO%), and six-minute walk distance (SMWD) over time; and survival in the entire cohort and according to CTD-like subgroups and radiological patterns. RESULTS: Fifty-nine patients fulfilled IPAF criteria. FVC%, DLCO%, and SMWD remained stable over time. There was no difference between usual interstitial pneumonia (UIP) versus non-UIP radiologic patterns. Thirty-five patients were sub-classified into CTD-like subgroups. Survival decreased from 79% at 60 months to 53% at 120 months in the entire cohort but was similar among CTD-like subgroups and radiological patterns. CONCLUSIONS: Long-term pulmonary function and six-minute walk test remained stable over 36 months in our IPAF cohort. Prognosis and pulmonary function in UIP had similar outcomes compared to non-UIP. Although 40% of IPAF patients could not be sub-classified, our exploratory subclassification stratified 60% of patients into a CTD-like subgroup.

Magnetic resonance measurement of muscle T2, fat-corrected T2 and fat fraction in the assessment of idiopathic inflammatory myopathies.

OBJECTIVE: This study examines the utility of MRI, including T2 maps and T2 maps corrected for muscle fat content, in evaluating patients with idiopathic inflammatory myopathy. METHODS: A total of 44 patients with idiopathic inflammatory myopathy, 18 of whom were evaluated after treatment with rituximab, underwent MRI of the thighs and detailed clinical assessment. T2, fat fraction (FF) and fat corrected T2 (fc-T2) maps were generated from standardized MRI scans, and compared with semi-quantitative scoring of short tau inversion recovery (STIR) and T1-weighted sequences, as well as various myositis disease metrics, including the Physician Global Activity, the modified Childhood Myositis Assessment Scale and the muscle domain of the Myositis Disease Activity Assessment Tool-muscle (MDAAT-muscle). RESULTS: Mean T2 and mean fc-T2 correlated similarly with STIR scores (Spearman rs = 0.64 and 0.64, P < 0.01), while mean FF correlated with T1 damage scores (rs = 0.69, P < 0.001). Baseline T2, fc-T2 and STIR scores correlated significantly with the Physician Global Activity, modified Childhood Myositis Assessment Scale and MDAAT-muscle (rs range = 0.41-0.74, P < 0.01). The response of MRI measures to rituximab was variable, and did not significantly agree with a standardized clinical definition of improvement. Standardized response means for the MRI measures were similar. CONCLUSION: Muscle T2, fc-T2 and FF measurements exhibit content validity with reference to semi-quantitative scoring of STIR and T1 MRI, and also exhibit construct validity with reference to several myositis activity and damage measures. T2 was as responsive as fc-T2 and STIR scoring, although progression of muscle damage was negligible during the study.