Objective: To compare anti-Th/To-positive and anticentromere antibody (ACA)-positive patients with limited cutaneous systemic sclerosis (lcSSc).
Methods: We reviewed the medical records of 107 anti-Th/To-positive patients and 365 ACA-positive patients who were first evaluated during 1985-2000. ACA was detected by indirect immunofluorescence on HEp-2 cell substrate, and anti-Th/To was detected by RNA immunoprecipitation with K562 cell extracts. Patients were included if they had a clinical diagnosis of lcSSc, and excluded if they had >1 SSc-associated serum autoantibody.
Results: The final study groups comprised 87 lcSSc patients with anti-Th/To antibodies and 306 with ACAs. Anti-Th/To-positive patients were younger (P < 0.04) and had a shorter disease duration at their first evaluation (P < 0.003). Patients with anti-Th/To antibodies had more subtle skin changes, less severe vascular involvement, and less frequent distal esophageal hypomotility. Both groups had a higher frequency of "intrinsic" pulmonary hypertension than has been previously reported in the literature (28% and 19% of anti-Th/To-positive and ACA-positive patients, respectively), perhaps due to referral bias. Patients in the anti-Th/To group more often had radiographic evidence of interstitial lung disease (48% versus 13% of the ACA group; P < 0.0001). Scleroderma renal crisis was uncommon (4 cases), but occurred exclusively in the anti-Th/To group. Survival among the anti-Th/To-positive patients was reduced compared with that in the ACA group (P < 0.02).
Conclusion: Patients with anti-Th/To and those with ACA most often develop lcSSc and have a high frequency of "intrinsic" pulmonary hypertension. Compared with the ACA patients, anti-Th/To lcSSc patients have more subtle cutaneous, vascular, and gastrointestinal involvement, but more often have certain features typically seen in diffuse scleroderma, such as pulmonary fibrosis and scleroderma renal crisis, as well as reduced survival.