Longterm Efficacy and Safety of Monotherapy versus Combination Therapy in Systemic Sclerosis-associated Pulmonary Arterial Hypertension: A Retrospective RESCLE Registry Study.

Monotherapy is an option as first-line therapy for pulmonary arterial hypertension (PAH). However, combination therapy is a beneficial alternative. Our objective was to evaluate the efficacy of monotherapy versus combination therapy in patients with systemic sclerosis (SSc)-associated PAH. All patients with SSc-associated PAH from the Spanish Scleroderma Registry (RESCLE) were reviewed. Patients were split into 3 groups: monotherapy versus sequential combination versus upfront combination therapy. The primary endpoint was death from any cause at 1, 3, and 5 years from PAH diagnosis. Seventy-six patients (4.2%) out of 1817 had SSc-related PAH. Thirty-four patients (45%) were receiving monotherapy [endothelin receptor antagonist (n = 22; 29%) or phosphodiesterase-5 inhibitors (n = 12; 16%)], 25 (33%) sequential combination, and 17 (22%) upfront combination therapy. A lower forced vital capacity/DLCO in the sequential combination group was reported (2.9 ± 1.1 vs 1.8 ± 0.4 vs 2.3 ± 0.8; p = 0.085) and also a higher mean pulmonary arterial pressure in combination groups (37.2 ± 8.7 mmHg vs 40.8 ± 8.8 vs 46 ± 15.9; p = 0.026) at baseline. Treatment regimen (p = 0.017) and functional class (p = 0.007) were found to be independent predictors of mortality. Sequential combination therapy was found to be an independent protective factor (HR 0.11, 95% CI 0.03-0.51; p = 0.004), while upfront combination therapy showed a trend (HR 0.68, 95% CI 0.23-1.97; p = 0.476). Survival from PAH diagnosis among monotherapy, sequential, and upfront combination groups was 78% versus 95.8% versus 94.1% at 1 year, 40.7% versus 81.5% versus 51.8% at 3 years, and 31.6% versus 56.5% versus 34.5% at 5 years (p = 0.007), respectively. Side effects were not significantly different among groups. Combination sequential therapy improved survival in our cohort.