Pulmonary function measures predict mortality differently in IPF versus combined pulmonary fibrosis and emphysema

Abstract

The composite physiologic index(CPI) was derived to represent the extent of fibrosis on high resolution computed tomography, adjusting for emphysema in patients with idiopathic pulmonary fibrosis(IPF). We hypothesized longitudinal change in CPI would better predict mortality than forced expiratory volume in 1 second(FEV1), forced vital capacity(FVC), or diffusing capacity for carbon monoxide(DLCO) in all patients with IPF, and especially in those with combined pulmonary fibrosis and emphysema(CPFE). Cox proportional hazard models were performed on pulmonary function data from IPF patients at baseline (n=321), 6 months (n=211) and 12 months (n=144). Presence of CPFE was determined by high resolution computed tomography. A 5 point increase in CPI over 12 months predicted subsequent mortality (HR 2.1, p=0.004). At 12 months, a 10% relative decline in FVC, a 15% relative decline in DLCO or an absolute increase in CPI of 5 points all discriminated median survival by 2.1 to 2.2 years versus patients with lesser change. Half our cohort had CPFE. In patients with moderate/severe emphysema, only a 10% decline in FEV1 predicted mortality (HR 3.7, p=0.046). In IPF, a 5 point increase in CPI over 12 months predicts mortality similarly to relative declines of 10% in FVC or 15% in DLCO. For CPFE patients, change in FEV1 was the best predictor of mortality.

Idiopathic Pulmonary Fibrosis With Emphysema: Evidence of Synergy Among Emphysema and Idiopathic Pulmonary Fibrosis in Smokers

“…6,7 The proportion of patients with pulmonary fibrosis who also have emphysema ranges from 8% to 50.9%. [7][8][9] However, other patterns of fibrotic lung disease have also been reported in conjunction with emphysema. 5,10,11 CPFE syndrome has been described in patients with connective tissue disease.…”

The impact of emphysema in pulmonary fibrosis

“…All Cox models are adjusted for the baseline average pulmonary function test, average age at diagnosis of 62 years, male sex and positive smoking history. Reproduced from [35]. Bullae 54…”

“…This index is simple to calculate (based on % predicted DLCO, FVC and FEV1), and has been shown to reflect the extent of disease more accurately than single physiological indices and is also a powerful predictor of mortality ( fig. 1) [35].…”

Significance of Combined Emphysema in Idiopathic Pulmonary Fibrosis and Serum Surfactant Protein-D as a Prognostic Factor

“…8,9,[28][29][30][31] There seem to be two explanations for this: differences in the assessment of emphysema area on HRCT and race differences. Standardization of diagnosis criteria and a large-scale study that takes race into consideration are areas for future research.…”

“…[8][9][10][11] Our results showed that the CPFE group revealed a significantly worse prognosis than did the non-CPFE group when the threshold of ratio of emphysematous area on HRCT was set at 25%, but no significant difference was found at 10% (Figure 1). Regarding PFTs, a large cohort study of patients with IPF suggested that a decline in FVC of more than 10% in IPF 13 and that in FEV 1 of more than 10% in moderate-to-severe CPFE 28 during a 6-month observation are the best physiological predictors of mortality. On the other hand, the present study suggested that an annual decline of more than 5% in % DLCO was a good predictor in the CPFE group, but that FVC and FEV 1 were not.…”