Iron deficiency in systemic sclerosis patients with and without pulmonary hypertension

SSc-associated pulmonary hypertension (SSc-PH) has a worse prognosis compared with SSc without PH (SSc-nonPH). Iron deficiency (ID) was previously associated with worse clinical outcome and survival in other types of PH, but ID effects in SSc-PH are unknown. Therefore we investigated the prevalence and clinical significance of ID in systemic sclerosis patients with and without PH.

Body iron status was determined in SSc-PH (n = 47) and SSc-nonPH patients (n = 122). ID was defined by circulating soluble transferrin receptor (sTfR) levels >28.1 nmol/l. Clinical and exercise parameters were compared between the groups. Four-year survival after iron measurements was determined.

ID prevalence was 46.1% in SSc-PH compared with 16.4% in SSc-nonPH patients (P < 0.001). Overall hepcidin levels were high compared with reference values and related to sTfR, but not with IL-6 (P = 0.82). Six-minute walking distance and maximal achieved work at ergometry was lower in SSc-PH compared with SSc-nonPH patients (P < 0.001 and P < 0.01, respectively) and was even further reduced in case of ID (P(interaction) < 0.05). In addition, ID SSc-PH patients had a poorer survival compared with non-ID patients [hazard ratio (HR) 0.34, 95% CI 0.14, 0.82, P < 0.05) and a similar trend was observed in SSc-nonPH patients (HR 0.16, 95% CI 0.02, 1.11, P = 0.06).

ID is more prevalent in SSc-PH than in SSc-nonPH patients and is associated with exercise impairment in both SSc-PH and SSc-nonPH. In addition, ID SSc-PH patients have a significantly worse survival compared with non-ID patients.