Step 2

Step 1 total risk score
Right atrium area
Right atrium area
An echocardiographic parameter that is routinely measured in patients with PAH. Right atrial enlargement is one indication of right ventricular dysfunction and is a predictor of mortality in PAH patients.
TR velocity
Tricuspid regurgitation velocity
An echocardiographic variable that is used in the Bernoulli equation to estimate systolic pulmonary arterial pressure. Tricuspid regurgitation is the backflow of blood from the right ventricle to the right atrium during right ventricular contraction. An elevated tricuspid regurgitation velocity is an indication of PH.
no TR velocity not reported but RVSP
TR velocity not reported but RVSP
If TR velocity is not reported, it can be calculated by entering values for RVSP and RAP. Therefore, if both RVSP and RAP are reported, please enter the values accordingly. If only RVSP is reported, RAP may be assumed according to the following rule of thumb: if reported RVSP < 40 mmHg, assign RAP 5; if RVSP 40-60 mmHg, assign RAP 10; if RVSP > 60, assign RAP 15.
no No measurable TR
No measurable TR
Sometimes the tricuspid regurgitation is only minimal and it may not be possible to measure it accurately or not at all. In this case, please check this box. The missing value is automatically imputed based on the DETECT data pool.


Step 2 total risk score

RHC recommended
10 35 40 90

The PAH risk calculator (based on the DETECT screening algorithm) has been designed to minimize the rate of missed PAH diagnoses which was as low as 4% in the DETECT study. To achieve this high sensitivity, in some of your patients the right heart catheterization (RHC) will be negative (absence of PAH) although the calculator recommended RHC. Nevertheless, even in the risk range which is just above the threshold for RHC referral (between 35 and 40 points on the risk score) up to 15% of your scleroderma patients have undiagnosed PAH.

The PAH risk calculator cannot replace your specialist clinical judgment. Actelion Pharmaceuticals Ltd does not assume any responsibility for use of the PAH risk calculator.

How to use

Enter the values for each variable in the boxes provided.

Click ‘calculate’ to generate the Step 2 total risk score.

Missing variables

All variables are needed for the Step 2 total risk score to be calculated. If TR velocity cannot be determined because no TR is detectable upon echocardiography (see tickbox "No measurable TR"), this does not count as a missing variable.


The paper nomogram of the PAH risk calculator provides an alternative to the electronic version available on this website. It may be particularly helpful to demonstrate and explain the tool to colleagues, physicians in training, and students. The paper nomogram can be downloaded here. For guidance on how the nomogram works, please refer to the dedicated page How it works in the WHAT IS DETECT section of this website.