|Title||Relative versus absolute change in forced vital capacity in idiopathic pulmonary fibrosis.|
|Publication Type||Journal Article|
|Year of Publication||2012|
|Authors||Richeldi, L, Ryerson, CJ, Lee, JS, Wolters, PJ, Koth, LL, Ley, B, Elicker, BM, Jones, KD, King, TE, Ryu, JH, Collard, HR|
|Date Published||2012 May|
|Keywords||Female, Follow-Up Studies, Humans, Idiopathic Pulmonary Fibrosis, Logistic Models, Lung Transplantation, Male, Survival Analysis, Vital Capacity|
BACKGROUND: Decline in forced vital capacity (FVC) over time reliably predicts mortality in patients with idiopathic pulmonary fibrosis. The use of this measure in clinical practice is recommended by current evidence-based guidelines. It is unknown if the method of calculating decline in FVC (relative vs. absolute change) impacts its frequency or its ability to predict mortality.METHODS: Patients with idiopathic pulmonary fibrosis from two prospective cohorts were included if they had a baseline and 12-month follow-up FVC. A ≥10% decline in FVC from baseline was calculated in two ways: a relative decline of 10% (e.g., from 60% predicted to 54% predicted) and an absolute decline of 10% (e.g., from 60% predicted to 50% predicted). The frequency of a ≥10% decline in FVC and its ability to predict 2-year transplant-free survival were compared between these two methods. Declines in FVC of ≥5% and ≥15% were similarly compared. Analyses were performed unadjusted and adjusted for age, gender, use of oxygen, baseline FVC and baseline diffusion capacity for carbon monoxide.RESULTS: The frequency of any given FVC decline was significantly greater using the relative change in FVC method. For ≥10% decline, both methods predicted 2-year transplant-free survival with similar accuracy, and remained significant predictors after adjusting for baseline characteristics. The absolute change method appeared more predictive for ≥5% decline.CONCLUSIONS: Using the relative change in FVC maximises the chance of identifying a ≥10% decline in FVC without sacrificing prognostic accuracy. This may not hold true for ≥5% decline in FVC. These findings have important implications for clinical practice and the design of clinical trials.
|Grant List||HL086516 / HL / NHLBI NIH HHS / United States|