Predicting Outcome in Idiopathic Pulmonary Fibrosis: Addition of Fibrotic Score at Thin-Section CT of the Chest to Gender, Age, and Physiology Score Improves the Prediction Model

Abstract

To assess the impact of adding thin-section CT-derived semiquantitative fibrotic score to gender, age, and physiology (GAP) model for predicting survival in idiopathic pulmonary fibrosis (IPF). Materials and Methods:In this retrospective study of 194 patients with IPF, primary outcome was transplant-free survival. Two thoracic radiologists visually estimated the percentage of reticulation and honeycombing at baseline thin-section CT, which were added to give fibrotic score. For analysis, fibrotic score cutoff (x) determined by using receiver operating characteristic analysis categorized patients into group A (,x) and group B (x). Another categorization based on GAP score created group 1 (score 0-3) and group 2 (score 3). Combining the above categories gave four groups (A1, A2, B1, B2). Kaplan-Meier survival analysis was performed with comparison statistics (log-rank test), and hazard ratios were calculated by using the Cox model. Results:The study patients included 141 men (72.7%), with average age of 66.1 years 6 9.1 (standard deviation). Eighty-four patients (43.3%) has stage I disease with a median follow up of 3.3 years. The interobserver agreement for thin-section CT fibrotic score was substantial (83.3%; k = 0.64). The optimal cutoff for fibrotic score was 25% (x), with area under the curve of 0.654 (95% confidence interval [CI]: 0.569, 0.74). Survival for group A1 was significantly better than in the other three groups (P < .001). The hazard ratios for respective groups were as follows: B1 was 4.03 (95% CI: 2.02, 8.07), A2 was 4.10 (95% CI: 1.89, 8.87), and B2 was 5.62 (95% CI: 2.86, 11.06) (P , .001 for all). Within the group with GAP score less than or equal to 3 (A1, B1), participants with higher fibrotic score (B1) had four times the increased risk of death or transplantation (P , .001). Conclusion:Incorporating semiquantitative fibrotic score from thin-section CT to GAP score provides an improved prediction model for survival in idiopathic pulmonary fibrosis.

Importance of chest HRCT in the diagnostic evaluation of fibrosing interstitial lung diseases

“…Ley et al (48) obtiveram um desempenho comparável ao do escore GAP substituindo o parâmetro da DLCO por um escore visual semiquantitativo de TCAR. Mais recentemente, Chahal et al (49) propuseram um modelo que adiciona uma avaliação tomográfica semelhante (escore visual semiquantitativo de fibrose acima ou abaixo de 25%) ao escore GAP, melhorando a predição do desfecho de sobrevida, especialmente em pacientes com doença em grau leve. Outras propostas de estadiamento multiparamétricas que incluem variáveis funcionais e avaliação tomográfica têm sido descritas para PIF relacionada a esclerose sistêmica, sarcoidose e outras manifestações.…”

“…Ley et al 48 replaced DLCO with a visual semiquantitative HRCT score and reported that the resulting model had a performance that was comparable to that of the original GAP model. Chahal et al 49 evaluated the impact of adding a visual semiquantitative fibrotic score above or below 25% to the GAP model and found that the resulting model shows improved correlation with survival, especially in patients with mild disease. Other multidimensional indices including functional variables and CT evaluation have been proposed to stage systemic sclerosis-related fibrosing ILD, sarcoidosis, and other ILDs.…”

A survival analysis of idiopathic pulmonary fibrosis in the context of antifibrotic therapy in Saudi Arabia

“…A recent study reported incorporating semi-quantitative fibrotic score from thin-section Computed tomography and GAP score provided a better prediction for survival in IPF. [ 24 ] However, these findings need to be confirmed in prospective studies.…”

“…[ 25 26 ] The most dynamic system of gauging disease severity in IPF is likely to integrate biomarkers with longitudinal physiological data and changes identified on imaging. [ 10 24 ]…”

CT quantification of the heterogeneity of fibrosis boundaries in idiopathic pulmonary fibrosis

“…The visually assessed extent of fibrosis on CT images is a predictor of survival in IPF patients [7][8][9][10]. Furthermore, the CT-derived extent of fibrosis can be used as a supplement to the GAP score to improve the capability of predicting survival [11], or as a substitute for DLCO in the GAP model [12]. However, the visual evaluation of fibrosis on CT can be limited by the subjective interpretation or degree of experience of the reader, causing inter-observer variation [13].…”