The revised definition of acute exacerbation (AE) in patients with idiopathic pulmonary fibrosis (IPF) may result in discrepancies between past and current epidemiological measures, according to a new study published in Scientific Reports.

“Per the revised definition, approximately a fifth of patients with IPF experienced AE which exerted a significant impact on the prognosis,” Yoo and colleagues wrote. They determined that the newest definition translates into a 20.4% increase in the incidence of AE and a 10.1% decrease in the mortality of hospitalized patients.

This retrospective study included 445 patients previously diagnosed with IPF, analyzing their clinical data. The patients had a median follow-up period of 36.8 months. The multivariable analysis aimed to determine shifts in epidemiological data regarding AE and other outcomes.

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Among the revised population, 17.5% experienced AE with incidences in the first and third year of 6.7% and 16.6%, respectively, following the new definition; only 14.4% of the participants experienced AE according to the previous criteria. The vast majority of events (82.1%) were idiopathic.

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However, some risk factors could be identified, such as age, lung diffusion capacity impairment for carbon monoxide, and a relative decline in forced vital capacity of at least 10% over 6 months. Significantly, AE was independently associated with poor prognosis, and the in-hospital mortality rate associated with such events reached 29.5%. Almost half (46.5%) of the patients died at some point during follow-up.

The revised definition of AE in IPF includes any respiratory event that promotes an acute or subacute development or worsening of dyspnea; nevertheless, most previous research that reported the epidemiological significance of AE used the old definition.

Moreover, all cases of suspected AE with the old definition were included as clear AE with the revised term. “This finding suggests that more patients with IPF may be eligible for future clinical trials involving AE-IPF,” the authors concluded.


Yoo JW, Kim J, Song JW. Impact of the revised definition on incidence and outcomes of acute exacerbation of idiopathic pulmonary fibrosis. Sci Rep. 2022;12:8817. doi:10.1038/s41598-022-12693-5