OBJECTIVES: Cost-effectiveness (CE) models for idiopathic pulmonary fibrosis (IPF) treatments that have been submitted to the National Institute for Health and Care Excellence (NICE) for health technology assessments have not explicitly linked lung function decline to survival, citing a lack of suitable data. Our objective was to review the IPF disease literature for compatibility with existing IPF mortality prediction models to inform approaches linking lung function to survival in future CE analyses.
METHODS: Clinical experts identified 3 IPF mortality prediction models for consideration on the basis of their real-world clinical utility. The mortality prediction models (Gender-Age-Physiology [GAP], longitudinal GAP, and du Bois et al.) all relied on percent predicted forced vital capacity (ppFVC) and at least 1 of acute exacerbations, percent predicted diffusing capacity of the lung for carbon monoxide (ppDLCO), or 6-minute walking distance (6MWD). We reviewed the IPF progression literature as of October 1, 2023, for studies reporting rates of ppFVC, ppDLCO, and 6MWD change; acute exacerbation risks; and correlations among these outcomes.
RESULTS: We identified 10 key studies reporting rates of ppFVC, ppDLCO, and 6MWD change; acute exacerbation risks; and correlations among these outcomes. These studies suggested a heterogeneous disease course, especially in patterns of ppFVC decline and acute exacerbations. Study findings indicated that ppFVC level was correlated with ppDLCO and 6MWD levels and that the rate of ppFVC change was correlated with rates of change for ppDLCO and 6MWD and with acute exacerbation risk. Limited data were available to inform other potential relationships (e.g., ppFVC level and change in ppFVC).
CONCLUSIONS: This targeted literature review identified evidence on IPF disease progression that supports clinically relevant mortality prediction approaches for future CE analyses. The heterogeneous course of IPF progression and observed correlations among measures of decline suggest that a patient-level simulation modeling approach may be appropriate for assessing cost-effectiveness in IPF.
