Background and objective: Pulmonary hypertension (PH) is associated with increased mortality in fibrotic idiopathic interstitial pneumonia (IIP). We hypothesize that baseline K(CO) (diffusing capacity of carbon monoxide/alveolar volume) and 6-month decline in K(CO) reflect PH, thus predicting mortality in IIP.
Methods: All IIP referrals (2004-2007) were identified (n = 269). 192 had pulmonary function at 6 months. Fifty-two (27%) died during follow-up (median 22.5 months). Outcome was evaluated for early (1 year from 6-month pulmonary function) and overall mortality. A vascular index best predicting mortality was identified (using baseline and 6-month decline in K(CO) ) and evaluated against PH at echocardiography.
Results: Baseline and 6-month decline in K(CO) were associated with early and overall mortality. A positive vascular index (baseline K(CO) % ≤ 50% and/or ≥15% decline in K(CO) at 6 months; n = 40) was strongly predictive of early and overall mortality. Neither a diagnosis of idiopathic pulmonary fibrosis nor PH predicted early death when incorporated into this model. In patients without baseline PH, with follow-up echocardiography (n = 60), a positive vascular index was associated with PH at follow-up.
Conclusions: A vascular index comprised of baseline and 6-month decline in K(CO) strongly predicted increased mortality and development of PH on echocardiography. In, K(CO) may be an important marker for pulmonary vascular disease and its associated mortality.
© 2011 The Authors. Respirology © 2011 Asian Pacific Society of Respirology.