Assessing the severity of PAH
The severity of symptoms and the degree of physical limitation in patients with Pulmonary Arterial Hypertension (PAH) may be assessed by World Health Organization functional class, WHO FC (see Table 1 below). Such assessment provides useful information on the current level of physical function, correlates to prognosis and can help guide decisions on therapy. There are four WHO functional classes for Pulmonary Arterial Hypertension (PAH), with class I being the least severe and class IV being the most advanced.1
Pulmonary Arterial Hypertension (PAH) is a devastating disease, which can progress rapidly, even in mildly symptomatic patients. Without treatment, patients in WHO FC II can rapidly deteriorate within 6 months to more advanced Pulmonary Arterial Hypertension (PAH) as evidenced by progression of symptoms.2
Table 1. NYHA/WHO Classification of Functional Status of Patients With Pulmonary Hypertension1
| Class |
Symptomatic profile |
| Class I |
Patients with pulmonary hypertension but without resulting limitation of physical activity. Ordinary physical activity does not cause Dyspnoea or fatigue, chest pain or near syncope |
| Class II |
Patients with pulmonary hypertension resulting in slight limitation of physical activity. They are comfortable at rest. Ordinary physical activity causes undue dyspnoea or fatigue, chest pain or near syncope |
| Class III |
Patients with pulmonary hypertension resulting in marked limitation of physical activity. They are comfortable at rest. Less than ordinary activity causes undue dyspnoea or fatigue, chest pain or near syncope |
| Class IV |
Patients with pulmonary hypertension with inability to carry out any physical activity without symptoms. These patients manifest signs of right heart failure. Dyspnoea and/or fatigue may even be present at rest. Discomfort is increased by any physical activity. |
References
1. Barst RJ, McGoon M, Torbicki A, et al. Diagnosis and differential assessment of pulmonary arterial hypertension. J Am Coll Cardiol 2004;43:40S-47S.
2. Galiè N, Rubin LJ, Hoeper MM et al. Treatment of patients with mildly symptomatic pulmonary arterial hypertension with bosentan (EARLY study): a double-blind, randomised controlled trial. Lancet 2008; 371: 2093-2100.
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