title: Evaluation of recently validated non- invasive formula using basic lung functions as new screening tool for pulmonary hypertension in idiopathic pulmonary fibrosis patients.
abstract: BACKGROUND
  A prediction formula for mean pulmonary artery pressure (MPAP) using standard lung function measurement has been recently validated to screen for pulmonary hypertension (PH) in idiopathic pulmonary fibrosis (IPF) patients.
  
  
  OBJECTIVE
  To test the usefulness of this formula as a new non invasive screening tool for PH in IPF patients. Also, to study its correlation with patients' clinical data, pulmonary function tests, arterial blood gases (ABGs) and other commonly used screening methods for PH including electrocardiogram (ECG), chest X ray (CXR), trans-thoracic echocardiography (TTE) and computerized tomography pulmonary angiography (CTPA).
  
  
  METHODS
  Cross-sectional study of 37 IPF patients from tertiary hospital. The accuracy of MPAP estimation was assessed by examining the correlation between the predicted MPAP using the formula and PH diagnosed by other screening tools and patients' clinical signs of PH.
  
  
  RESULTS
  There was no statistically significant difference in the prediction of PH using cut off point of 21 or 25 mm Hg (P = 0.24). The formula-predicted MPAP greater than 25 mm Hg strongly correlated in the expected direction with O₂ saturation (r = -0.95, P < 0.000), partial arterial O₂tension (r = -0.71, P < 0.000), right ventricular systolic pressure measured by TTE (r = 0.6, P < 0.000) and hilar width on CXR (r = 0.31, P = 0.03). Chest symptoms, ECG and CTPA signs of PH poorly correlated with the same formula (P > 0.05).
  
  
  CONCLUSIONS
  The prediction formula for MPAP using standard lung function measurements is a simple non invasive tool that can be used as TTE to screen for PH in IPF patients and select those who need right heart catheterization.
authors.affiliation: Department of Chest Disease, Faculty of Medicine, Assiut University Hospital, Assiut - 71111, Egypt. mahaghanem@hotmail.com
authors.forename: Maha K
authors.initials: MK
authors.lastname: Ghanem
authors.forename: Hoda A
authors.initials: HA
authors.lastname: Makhlouf
authors.forename: Gamal R
authors.initials: GR
authors.lastname: Agmy
authors.forename: Hisham M K
authors.initials: HM
authors.lastname: Imam
authors.forename: Doaa A
authors.initials: DA
authors.lastname: Fouad