Accuracy of High Resolution Computed Tomography, Lung Function Tests in SSc Evaluated in New Study

Accuracy of High Resolution Computed Tomography, Lung Function Tests in SSc Evaluated in New Study

In a recent study published in the journal Arthritis & Rheumatology, researchers found that high resolution computed tomography (HRCT) predicts fibrosis development, rate of fibrosis progression and pulmonary function decline in Systemic sclerosis (SSc).

Systemic sclerosis (SSc) is a major challenge in clinical practice; the disease is heterogeneous, has unpredictable outcomes, and no disease modifying therapies are available. Mortality rates are increased and mainly driven by two cardiopulmonary disease components; pulmonary hypertension (PH) causing right-sided heart failure, and interstitial lung disease (ILD) progressing to extensive lung fibrosis.

Pulmonary function tests (PFT) are key instruments for SSc-ILD assessment in daily clinical practice, and forced vital capacity (FVC) has also been highlighted as a core outcome measure for clinical trials in a recently published expert opinion reports.

SSc patients with abnormal PFTs and/or ILD symptoms are routinely investigated by high resolution computed tomography (HRCT). This modality detects ILD with higher sensitivity than ordinary x-ray,(13) differentiates between abnormalities in airways and parenchyma, and allows quantitative assessment of the changes observed.

In the study titled Predictive value of serial HRCT analyses and concurrent lung function tests in systemic sclerosis,” Anna-Maria Hoffmann-Vold, MD PhD from Oslo University Hospital in Norway along with colleagues conducted serial HRCTs and corresponding PFTs in a large, prospective population of 305 patients with SSc, covering the whole spectrum of disease severities.

Paired PFTs and high resolution computed tomography (HRCT) images were obtained at baseline and follow-up and the extent of fibrosis was scored on 10 sections from every HRCT and expressed as percentage of total lung volumes.

The results showed that the frequency of SSc patients with lung fibrosis was stable across the observation period, and that the annual fibrosis progression rate was associated to the extent of fibrosis at baseline.

The researchers also found that the baseline HRCT predicted fibrosis development and deterioration in lung function, and that the extent of lung fibrosis and the fibrosis progression rate were not associated with mortality.

Results indicate that a baseline examination in newly diagnosed SSc patients should include both lung HRCT and PFTs, as it appears that these two modalities together efficiently segregate patients in subsets with low and high SSc-ILD risk. Patients with low ILD risk should not undergo serial HRCT examinations, but probably need serial PFTs as an adjunct PH detection tool.

According to the researchers, these results do not provide unequivocal answers regarding the value of serial HRCT examinations in patients with fibrosis already on the baseline HRCT.

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