Predictors of Isolated Pulmonary Hypertension in Patients with Systemic Sclerosis and Limited Cutaneous Involvement

Objective: To determine whether there are factors, such as the diffusing capacity for carbon monoxide (DLCO) or pulmonary artery pressure (PAP) on echocardiogram, that can predict the development of pulmonary hypertension (PHT) in patients with limited scleroderma.

Methods: Using the large Pittsburgh Scleroderma Databank, 106 patients who had the diagnosis of PHT after January 1, 1982, were matched with 106 controls by scleroderma subtype, age, sex, race, disease duration, and the mean time to the diagnosis of PHT after the initial Pittsburgh visit. Autoantibodies, vascular features, use of calcium channel blockers, extent of pulmonary function, and echocardiogram findings were determined at any time prior to the diagnosis of PHT (or prior to the matched time in controls).

Results: Patients with PHT had a mean DLCO of 52% of predicted at an average of 4.5 years prior to the diagnosis of PHT. This was markedly decreased compared with the values in controls, whose mean DLCO was 81% of predicted (P < 0.0001). The estimated mean PAP on echocardiogram was only slightly higher in the PHT patients compared with controls (34 mm Hg versus 29 mm Hg; P not significant). Nineteen PHT patients had 4 serial measurements of the DLCO during the 15 years prior to the diagnosis of PHT. The initial mean DLCO was 80% of predicted, which decreased in a linear manner to a mean of 35% of predicted at the time of diagnosis of PHT, whereas the value in controls remained at approximately 80% of predicted (P < 0.0001). PHT patients had more severe Raynaud's phenomenon and more severe digital tip ulcers, but they used calcium channel blockers significantly less frequently (37% versus 61% of controls; P < 0.01). The predominance of nucleolar autoantibodies and the absence of anti-Scl 70 antibody were associated with PHT.

Conclusion: A decreasing DLCO is an excellent predictor of the subsequent development of isolated PHT in limited scleroderma. The DLCO may be significantly decreased for many years prior to the diagnosis of PHT. The presence of autoantibodies and the PAP may also be helpful predictors. The long-term use of calcium channel blockers may be protective, but newer agents that are more effective in treating PHT may also be helpful in altering the natural history of this serious complication in limited scleroderma.