Implementation and comparison of the first evidence-based detection algorithm for pulmonary arterial hypertension in systemic sclerosis vs current practice.
K.Robinson, G.Wright, A.Elliott, A.Flynn
Rheumatology Department, Musgrave Park Hospital, Belfast Trust, Northern Ireland.
Pulmonary arterial hypertension (PAH) is a leading cause of death in systemic sclerosis (SSc). Earlier detection of PAH facilitates earlier treatment. The DETECT study has developed the first evidence-based detection algorithm for PAH in SSc. Current practice is annual pulmonary function tests and echocardiograms. The issue with this method is that echo is not the most sensitive test for PAH. Pulmonary arterial pressure (PAP) cannot be calculated when there is no tricuspid regurgitation (TR) however; patients can have raised PAP despite having no TR. In the DETECT study they found that 7% of patients with RHC diagnosed PAH had no TR on echo. Note this was a high-risk population group and not comparable with the general population of SSc patients.
The aim of the study was to ensure implementation of the DETECT algorithm was practically feasible and that the algorithm was more sensitive than current practice in the general population of systemic sclerosis patients in Northern Ireland.
Randomly selected SSc patients were entered into the study. They had the appropriate investigations performed in order to complete the DETECT algorithm and had annual PFTs and echo requested (if not performed in the last year). The results from both methods were compared to ensure patients who scored <300 in step 1 of the algorithm and therefore would not be referred for an echo did not have raised PAP.
41 patients were recruited. 9 patients had incomplete investigations leaving 32 patients with completed algorithms and annual PFTs/echocardiograms. 27 patients scored <300 in step 1 and therefore would not be referred for echo or considered for right heart catherisation. 5 patients scored >300 in step 1 indicating they should have updated echo requested.
Of these 27 patients, all but 3 had normal estimated PAP on annual echo. 2 of the 3 patients had known pulmonary fibrosis and therefore their pulmonary hypertension was secondary to lung disease. The other patient with raised PAP was seen by a cardiologist who repeated the echo and found normal estimated PAP.
Of the 5 patients who scored >300 in step 1 of the algorithm, 3 patients scored >35 in step 2 and therefore should be referred for RHC. All of these patients had raised PAP on echo and so would have been referred for RHC based on the echo result alone.
Of the 32 patients included in our regional study using the DETECT algorithm did not detect PAH any earlier than current practice although the algorithm also did not miss any PAH diagnoses so we can conclude we found it equally as sensitive. However, our numbers are small and from the results in the DETECT study; the algorithm is a superior mode of earlier detection of PAH in SSc so we plan to change current practice and implement it long term. We also note it is not developed to identify any other causes of pulmonary hypertension, so patients with ILD should be excluded.