Objective: To determine the prevalence of right heart catheterization (RHC) confirmed pulmonary hypertension (PH) and the potential subtypes of PH and its associations with clinical characteristics and treatment response.
Materials and Methods: A historical cohort study was conducted of Thai SSc patients presenting at Srinagarind Hospital between January 2014 to December 2016. The PH subtypes were categorized using hemodynamic parameters from RHC, pulmonary function tests, and findings on high-resolution computed tomography (HRCT).
Results: 409 SSc patients were enrolled (F:M = 2.17:1); 75% had diffuse cutaneous SSc. The median age at the time of the study was 57 years (range, 20 to 87). and median disease duration was 4.83 years. The prevalence of PH was 9.5% and the estimated incidence of PH was 1.1 per 100 person-years. Among PH patients 97.4% (38/39) were pre-capillary, of whom 23 (60.5%) had PH due to interstitial lung disease (PH-ILD), 8 (21.1%) combined pulmonary arterial hypertension (PAH) and PH-ILD, 6 (15.8%) isolated PAH, and only 1 (2.6%) pulmonary veno-occlusive disease (PVOD). Pulmonary involvement >20% by HRCT was associated with the presence of PH. The treatment response to PAH-specific drug(s) was better among isolated PAH-SSc compared to subtypes with an interstitial lung component (83 vs. 62%).
Conclusion: The prevalence of PH among Thai patients with SSc was 9.5%; the majority was PH-ILD and combined PAH/PH-ILD. Isolated PAH was identified in 15.8%, which was associated with a better response to treatment. Pulmonary involvement >20% by HRCT was associated with the presence of PH.

Keywords: Systemic sclerosis; Pulmonary hypertension