Recent reports from worldwide pulmonary hypertension registries show a new demographic picture for patients with idiopathic pulmonary arterial hypertension (IPAH), with an increasing prevalence among the elderly. We aimed to investigate the effects of age and comorbidity on risk stratification and outcome of patients with incident IPAH. The study population (n=264) was categorised into four age groups: 18-45, 46-64, 65-74 and amp;gt;= 75 years. Individual risk profiles were determined according to a risk assessment instrument, based on the European Society of Cardiology and the European Respiratory Society guidelines. The change in risk group from baseline to follow-up (median 5 months) and survival were compared across age groups. In the two youngest age groups, a significant number of patients improved (18-45 years, Z=-4.613, pamp;lt; 0.001; 46-64 years, Z=-2.125, p=0.034), but no significant improvement was found in the older patient groups. 5-year survival was highest in patients aged 18-45 years (88%), while the survival rates were 63%, 56% and 36% for patients in the groups 46-64, 65-74 and. 75 years, respectively (pamp;lt; 0.001). Ischaemic heart disease and kidney dysfunction independently predicted survival. These findings highlight the importance of age and specific comorbidities as prognostic markers of outcome in addition to established risk assessment algorithms.