Pulmonary function testing (PFT) is a part of screening for ILD in patients with SSc, but there is a high false negative rate. A PFT conducted to evaluate for ILD may also show evidence of myopathy (e.g., with decreased forced vital capacity with normal diffusing capacity of the lungs for carbon monoxide [DLCO]) or pulmonary hypertension (e.g., decreased DLCO out of proportion to other parameters). PFTs can be helpful in following restrictive lung disease, and changes over time in PFT parameters can provide insight into disease activity.
On the subject of lung imaging, high-resolution computed tomography (CT) of the chest can help characterize ILD patterns, such as nonspecific interstitial pneumonia (NSIP) or usual interstitial pneumonia (UIP). If there are atypical findings on imaging, it is important to look for infections or malignancy. Fibrosis on CT imaging implies a poorer prognosis for patients.
Dr. Boin posed the question: Should all patients with SSc be screened with high-resolution CT of the chest? Although one survey-based study has indicated that a majority of rheumatologists would do so, it is not clear if this should be the standard of care.3
In the future, techniques for screening for ILD in SSc patients may include routine use of bronchoscopy and bronchoalveolar lavage, genetic testing (e.g., with single nucleotide polymorphisms and measuring telomere length) and exhaled breath analysis.
Pulmonary Hypertension
Pulmonary hypertension may be asymptomatic early in the SSc disease course. Risk factors for pulmonary hypertension include later age of onset, limited skin involvement, severe Raynaud’s and the presence of telangiectasias. Right heart catheterization is the gold standard for confirming pulmonary hypertension, and the key question is how best to identify which patients should undergo this testing.
The DETECT algorithm (https://www.suspectpahctd.com/DETECT) is a freely available tool with high sensitivity for detecting pulmonary hypertension (96%). However, this comes at the cost of low specificity, meaning a fair number of patients without pulmonary hypertension will be referred for right heart catheterization.
Dr. Boin described the balance of risks and benefits well: Although we want to avoid costly, unnecessary, and invasive tests, we also don’t want to miss pulmonary hypertension because it is associated with an increased risk of death. Detecting pulmonary hypertension earlier rather than later is ideal because effective therapies exist and can prevent severe complications.
Scleroderma Renal Crisis
Scleroderma renal crisis is a medical emergency for patients, explained Dr. Boin. Risk factors for this condition include early diffuse cutaneous disease, the presence of anti-RNA polymerase III antibodies and use of ≥15 mg of prednisone per day or lower doses of corticosteroids for longer periods of time.
