Is anti-topoisomerase I a serum marker of pulmonary involvement in systemic sclerosis?

Study objective: To determine the value of the level of anti-topoisomerase I (anti-topo I) to evaluate lung involvement defined by abnormal high-resolution computed tomography (HRCT) score and pulmonary function tests (PFTs) in systemic sclerosis (SS). Patients: Forty-eight patients with SS, 20 with lung involvement and 28 with no lung involvement. Design: PFT measurement, HRCT scoring of lung involvement, and anti-topo I assay by enzyme-linked immunosorbent assay. Normal anti-topo I level was defined as < 30. Results: There was a significant association between cutaneous extent and anti-topo I level (6.5% of patients with limited cutaneous scleroderma had abnormal anti-topo I levels vs 70.6% of patients with diffuse cutaneous scleroderma, p = 0.0001), In patients with diffuse cutaneous scleroderma, pulmonary involvement was associated with a higher percentage of abnormal anti-topo I level: 91.7% vs 20% (p = 0.010), In patients with diffuse cutaneous scleroderma, a significant association was found between the class of anti-topo I level and total lung capacity (median, 69 in patients with abnormal anti-topo I level vs 87 in patients with normal anti-topo I level, p = 0.010), between the class of anti-topo I level and HRCT score (median, 12 in patients with abnormal anti-topo I level vs 5 in patients with normal anti-topo I level, p = 0.05). Conclusion.. Anti-topo I can be considered as a marker of lung involvement in patients with diffuse cutaneous scleroderma.