Patients with idiopathic pulmonary fibrosis (IPF) who have a relative decline in peak expiratory flow rate (PEFR) may be at higher risk of mortality, according to a study published in Chronic Respiratory Disease.

Multivariate analysis found that a relative decline in PEFR increased a patient’s odds of death with a hazard ratio (HR) of 1.037 (95% CI, 1.002-1.072; P <.05). Baseline % predicted forced vital capacity (FVC) was another independent prognostic factor on multivariate analysis with an HR of 0.932 (95% CI, 0.905-0.960; P <.001).

During the study, the PEFR of 61 patients was observed at baseline and again after 6 months and followed for a median of 1017 days (530-1623 days). Almost one-third of the patients (21/61; 34.4%) died during the follow-up period. The median survival estimate during the study for the cohort was 2214 days.


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Using univariate Cox regression, body mass index, baseline percent-predicted FVC, baseline percent-predicted PEFR, percent-predicted diffusion capacity for carbon monoxide, a relative decline in FVC, and a relative decline in PEFR were all independent prognostic factors. In multivariate analysis, the only relative decline in PEFR and baseline percent-predicted FVC were factors, however.

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Using the area under the curve analysis of the receiver operating characteristic curve, a cutoff value of 8.65% was determined for the 2-year survival of patients. For patients with a decrease less than this amount, their mean survival estimate is around 2169 days while a relative decline of equal to or more than 8.65% resulted in a survival estimate of 1335 days.

For patients above the cutoff, there was a significant difference in baseline percent FVC and baseline percent forced expiratory volume in 1 second compared to the group below the cutoff.

“A decrease in PEFR after 6 months could be a novel and useful prognostic factor in patients with IPF. Progression of respiratory sarcopenia can be considered the cause of the decrease in PEFR. It is important to pay attention to PEFR in the clinical practice of IPF,” the authors concluded.

Reference

Fujita K, Ohkubo H, Nakano A, et al. Decreased peak expiratory flow rate associated with mortality in idiopathic pulmonary fibrosis: a preliminary report. Chron Respir Dis. 2022;19:14799731221114152. doi:10.1177/14799731221114153