Lung Disease Inadequately Assessed by FVC in PH-Scleroderma Patients

Patients with pulmonary hypertension secondary to scleroderma (also known as systemic sclerosis) may not be properly assessed for interstitial lung disease through forced vital capacity (FVC) alone, according to Dr. Elizabeth Volkmann, of the University of California, Los Angeles. Dr. Volkmann, a rheumatologist, spoke at the annual European Congress of Rheumatology held June 11-14 in Paris, France.

Instead, “A structural, physiologic, and patient-oriented composite outcome may be a more comprehensive measure of treatment response,” said Dr. Volkmann, as reported by Skin and Allergy News. Her findings came from an 83-patient trial related to scleroderma treatment. During her study, she found the Transition Dyspnea Index (TDI), the scleroderma modified Health Assessment Questionnaire Disability Index (HAQ-DI), and quantitative, serial assessment of high-resolution computed tomography (HRCT) images of patient lungs to be most robust in assessing interstitial lung disease in systemic sclerosis patients.

Patients were from a larger, 158-patient trial comparing oral cyclophophamide against placebo in patients with systemic sclerosis and interstitial lung disease. Multivariate analysis was used to find the best means for predicting the outcome of patients assessed with an HRCT scan at baseline and 12 months after treatment.

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The three tests were “more robust and comprehensive than FVC,” helping Dr. Volkmann meet her main goal of identifying the best assessment of lung disease in systemic sclerosis patients. Additionally, the results may impact how patients with systemic sclerosis are managed in routine practice.

Many physicians “rely solely on FVC for following patients, and I think this may not be the best measure,” said Dr. Volkmann. “Now that we have great imaging options we should use them. And the strongest correlates were with the HAQ-DI, a measure of what patients can do, and the TDI, in which patients say how much their diseases has progressed. They are both patient-oriented and tell you how the patient is doing.” In fact, when a model was created without FVC, slightly better predictions were made using HAQ-DI and TDI.

Yet a senior collaborator on the study, Dr. Daniel Furst, believes it is too early to stop using FVC to assess systemic sclerosis patients. What’s more, quantitative assessment of annual HRCT scans is not widely available, and the methodology has a variability of 10%.

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“We haven’t discarded FVC, but we’ve added the other things,” said Dr. Furst. “Five years ago we only did FVC, three years ago we added the scleroderma HAQ-DI.” Questionnaires are administered every three to six months, and Dr. Furst and colleagues use annual HRCT imaging with the TDI.

Since scleroderma is characterized by inflammation and tissue thickening, it can lead to pulmonary hypertension when blood vessels in the lungs are narrowed. According to the Scleroderma Program at the University of Michigan, 40% of scleroderma patients have narrowed lung blood vessels without lung scarring and inflammation. This aligns with the World Health Organization’s distinction of pulmonary arterial hypertension “as a distinct medical syndrome that shares common tissue features of non-inflammatory blood vessel narrowing.” Scleroderma patients may be better served by tests in addition to FVC to help determine if they have chronic lung disease that could lead to pulmonary hypertension.