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.
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