Definition of AEx-IPF
A universally agreed definition of an AEx-IPF has not been established. Clinical studies have used a variety of criteria to define AEx-IPF, which differ in factors such as whether chest X-ray, or high-resolution computed tomography (HRCT) is required, how hypoxemia is defined, and the conditions that must be ruled out. Variation in the definitions and methodology used to assess AEx-IPF has complicated researchers' and physicians' understanding of AEx-IPF and their impact.
In 2007, a consensus definition for AEx-IPF was proposed by an expert committee sponsored by the IPF Clinical Research Network and the National Heart Lung and Blood Institute (NHLBI), in an attempt to standardize the diagnostic criteria used across studies. This committee defined AEx-IPF as an acute, clinically significant deterioration of unidentifiable cause and proposed five diagnostic criteria ( Table 1 ). This definition has become the most widely used definition of AEx-IPF and has been used in several clinical studies.