Pulmonary Hypertension Association | Influence. Hope. Integrity Donate

Classifying PH

Pulmonary hypertension (PH) is classified according to how severe it is. This helps medical staff to understand how much PH is affecting someone, so they can find the right treatment.

The system that is used to classify PH was developed by the World Health Organization (WHO). It is based on how much exercise people with PH can do before they start to notice symptoms such as breathlessness.

WHO functional class 1

No symptoms of any kind; physical activity does not cause fatigue, palpitation, shortness of breath or chest pain.

WHO functional class 2

Comfortable at rest but symptoms occur with ordinary physical activity.

WHO functional class 3

Comfortable at rest but have symptoms with less-than-ordinary effort, eg lifting the arms.

WHO functional class 4

Symptoms while at rest