Pulmonary arterial hypertension in systemic sclerosis: a national inpatient analysis

Background:Pulmonary arterial hypertension (PAH) is a progressive, and eventually fatal complication of Systemic Sclerosis (SSc) that affects the prognosis, quality of life, and mortality rate. Non-specific manifestations of PAH can result in delayed diagnosis and therefore in poorer outcomes. Objectives: We aim to study the prevalence and epidemiology of pulmonary arterial hypertension in SSc, and the impact of PAH on SSc hospitalizations in the United States population. Methods: We utilized the National Inpatient Sample (NIS) from 2016-2019 to obtain adult hospitalizations with the primary/secondary diagnosis of SSc and coexistent PAH (SSc-PAH). Epidemiological variables, mortality rates, and secondary outcomes were studied including pulmonary embolism, atrial flutter, atrial and ventricular fibrillation, pneumonia, sepsis, cardiac arrest and cardiac & renal failure, and ventilator requirement. Healthcare burden was estimated from total hospital charges (THC) and length of stay (LOS). Statistical analysis was performed on STATA 16.1, using linear and logistic regression analyses. Results: Out of 126,685 adult systemic sclerosis hospitalizations, 16.89% had PAH (SSc-PAH). The SSc-PAH group had significantly more females (85.4 % vs. 83.8%) and higher mean age (64.85 +/- 13.29 vs. 62.56 +/- 14.51). More African Americans were in this group than in the control group (19.5% vs. 14.6, p-value<0.001) while Whites (61.3% vs. 65.6%, p<0.001) and Asians (18.0 % vs. 2.8%, p<0.001) were less common. Charlson comorbidity index was higher for the SSc-PAH population (3.42 vs. 2.94, p-value<0.001). SSc-PAH group had a higher adjusted odds ratio (aOR) for mortality (aOR: 1.39, p<0.001), increased LOS (6.64 vs. 6.0 days, p<0.001) increased THC ($83,813 vs. $71,016, p <0.001). For the SSc-PAH group, there were also significantly higher odds of cardiac failure (aOR 3.13), ventilator requirement (aOR 2.15), cardiac arrest (aOR 1.39), kidney failure (aOR 1.63), pulmonary embolism (aOR 1.84), atrial flutter (aOR 1.86) atrial fibrillation (aOR1.56) and pneumonia (aOR 1.22). No significant difference in ventricular fibrillation, sepsis, or respiratory failure was noted. Conclusion: Pulmonary arterial hypertension in SSc is associated with worse outcomes in terms of mortality and morbidity, and higher healthcare burden compared to SSc without PAH. Also, PAH disproportionately affects White, African American & Asian populations. There remains a pressing need to continue efforts for early diagnosis and management of PAH in SSc patients.