Prognosis in pulmonary arterial hypertension.

We read with interest the article by HUMBERT et al. [1] on the difference in prognosis in prevalent versus incident cohorts of patients with pulmonary arterial hypertension (PAH). The study highlights a survival bias in the prevalent cohort due to under-representation of more severely ill patients that might have died before inclusion in the registry. HUMBERT et al. [1] subsequently found a 1-yr and 3-yr survival rate of 89% and 69% for the prevalent cohort and 89% and 55% for the incident cohort of patients with idiopathic, familiar or anorexigen-associated PAH, respectively. Although we acknowledge that prevalent cohorts have a selection bias, it is surprising that this does not refer to a difference in mortality at 1-yr but only later during follow-up. If selection of the sickest patients would account for better survival one would expect the same phenomenon in the incident cohort. This would lead to a high early mortality rate, which then should stabilise over time as the sickest patients will have deceased. However, the prevalent patients have the disadvantage of potentially more advanced disease and, because of that, delayed start of targeted therapy. In contrast to the results reported by HUMBERT et al. [1] we found a better survival for the incident patients when compared with the prevalent ones in a cohort of 250 patients with idiopathic, familiar or anorexigen-associated PAH. These patients were enrolled at seven German pulmonary hypertension centres between 1996 and 2008. All patients enrolled at the time of diagnosis were defined as incidental, whereas all remaining patients were defined as prevalent case. All underwent baseline invasive haemodynamic studies and the results as well as the baseline clinical data are shown in table 1. Patients were subsequently started on targeted PAH therapy. Incident patients were started on inhaled iloprost (n511), oral beraprost (n58), bosentan (n521) or sildenafil (n56). 30 patients were switched to a different PAH therapy after 301¡67 days and 22 patients were started on combined PAH therapy after 632¡110 days. Prevalent patients were started on inhaled iloprost (n566), intravenous iloprost (n510), oral beraprost (n524), bosentan (n556) or sildenafil (n52). 78 patients were subsequently switched to a different PAH therapy (422¡46 days) and 46 patients treated with combined PAH therapy (807¡91 days). During a mean follow-up of 1408¡65 days 20 of the incident patients and 71 of the prevalent patients died. 25 patients underwent lung transplantation (one in the incident group). Overall survival …