High-resolution computed tomography (HRCT) is useful for the prognosis of patients with systemic scleroderma-related interstitial lung disease (SSc-ILD), research shows.
Patients with baseline HRCT imaging showing extensive disease - defined as more than 20% - were 3.0 times more likely to die or experience severe deterioration than patients with limited disease (<20%), after adjusting for age and other lung parameters.
Patients whose disease extent was unclear or indeterminate on HRCT were graded as having limited or extensive disease using a forced vital capacity threshold of 70%.
"Based on our study, we would propose the routine use of this HRCT grading system to obtain prognostic information in patients with SSc-ILD," say Mandana Nikpour (St Vincent's Hospital, Melbourne, Victoria, Australia) and co-authors.
They note in Rheumatology that this could be useful as patients with extensive SSc-ILD are thought to experience the most gain from cyclophosphamide and may also benefit from early immunosuppressive therapy.
The study followed up 172 SSc-ILD patients for an average of 3.5 years after HRCT, during which time there were 19 deaths, 10 patients required home oxygen, and one patient underwent lung transplantation.
Multivariate time-varying covariate analysis of 1309 serial pulmonary function tests (PFTs) and 353 serial HRCTs showed that a poor patient outcome was predicted by extensive lung disease on HRCT (hazard ratio [HR]=3.3).
Forced vital capacity (HR=0.9), serial diffusing capacity of the lung for carbon monoxide by alveolar volume ratio (HR=0.4), and increasing age (HR=1.06) were also significant markers for poor outcome.
Pulmonary hypertension, use of immunosuppressive therapy, and anti-Scl-70 antibodies were not associated with prognosis, however.
"We have shown that both serial HRCT and serial PFTs give prognostic information in SSc-ILD," say Nikpour et al.
Noting that a major change in HRCT disease extent was always accompanied by a 30% or greater decrease in PFT values, however, the team suggests that PFTs may be more practical than HRCT in the clinic. In particular, the researchers cite the risks associated with repeated HRCT radiation exposure, and the rapid, reproducible nature of PFTs.
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