Relationship between high-resolution computed tomography quantitative imaging analysis and physiological and clinical features in antisynthetase syndrome-related interstitial lung disease

Abstract

Objectives: To explore the association between the extent of CT abnormalities by quantitative imaging analysis (QIA) and clinical/physiological disease parameters in patients with antisynthetase syndrome associated interstitial lung disease (ARS-ILD).

Methods: We analysed 20 patients with antisynthetase antibodies and active ILD enrolled in the Abatacept in Myositis-Associated Interstitial Lung Disease study. High-resolution chest CT was obtained at weeks 0, 24 and 48 and QIA scored the extent of ground glass (quantitative score for ground glass), fibrosis (quantitative score for lung fibrosis, QLF) and total ILD (quantitative ILD, QILD). Mixed-effects models estimated longitudinal QIA scores over time. Associations between QIA scores with clinical/physiological parameters were analysed longitudinally using repeated-measures mixed-effects models.

Results: Patients were median age 57 years, 55% males and 85% white. Higher (worse) baseline QIA scores correlated with lower baseline forced vital capacity (FVC) and diffusing capacity adjusted for haemoglobin (DLCO). Longitudinal QIA trajectories trended towards improving scores during the trial, and patients on O₂ at baseline had worsening QIA trajectories which were different from patients who were not on O₂. Longitudinal QIA scores demonstrated strong associations with both FVC and DLCO over time. Higher QILD scores over time were also associated with worse dyspnoea scores, pulmonary visual analogue scale, physician and patient global disease activity, health status in 6/8 domains of the Short Form-36 and higher oxygen requirements. Patients with significant radiographic improvement at 48 weeks had higher baseline QLF, QILD and worse DLCO.

Conclusions: Longitudinal QIA scores associate with lung physiology, patient perception of respiratory status, overall disease activity and quality of life over time in ARS-ILD. QIA may allow reproducible monitoring of disease progression and response to therapy over time.

Trial registration number: NCT03215927.

Keywords: Dermatomyositis; Outcome Assessment, Health Care; Polymyositis; Pulmonary Fibrosis.

Figure 1. Quantitative CT scores (QIA-WL % scores) over time in all patients with HRCT scans (n=17). Bold lines are estimated trajectories of QIA (QGG, QLF, QILD) % whole lung scores over time (months) using mixed-effects models in 17 patients who had one or more HRCT scans adequate for QIA. Mean change±SE for QGG was −0.12±0.09 per month, p=0.21; for QLF −0.19±0.18 per month, p=0.30; for QILD −0.33±0.24 per month, p=0.19. HRCT, high-resolution chest CT; QGG, quantitative score for ground glass; QIA, quantitative image analysis; QILD, quantitative interstitial lung disease; QLF, quantitative score for lung fibrosis; WL, whole lung.

Figure 2. Longitudinal quantitative CT scores in different patient subgroups. P value of interaction term. Estimated trajectories of QIA (QGG, QLF, QILD) % whole lung scores over time (months) in patient subgroups by (a) baseline supplemental oxygen use and (b) baseline visual ILD pattern. ILD, interstitial lung disease; NSIP, non-specific interstitial pneumonia; OP, organising pneumonia; QGG, quantitative score for ground glass; QIA, quantitative image analysis; QILD, quantitative ILD; QLF, quantitative score for lung fibrosis.