Approximately one-third of patients are diagnosed with idiopathic pulmonary fibrosis (IPF) in Japan either during a routine health checkup or while undergoing an examination for another disease, while experiencing minimal or no respiratory symptoms, according to a new study published in Respiratory Medicine.

In spite of being diagnosed at a relatively early stage of disease, the survival among these individuals is nonetheless poor, with body mass index (BMI) being the sole independent predictor of survival.

Recognizing that IPF is a fatal, progressive fibrosing interstitial pneumonia of unknown cause, the investigators sought to elucidate the clinical course, prevalence, and prognostic factors of patients who are incidentally diagnosed with IPF. A retrospective review was conducted of consecutive patients who had received an IPF diagnosis at the Kindai University Hospital, Osakasayama in Japan between January 2008 and August 2017.

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All patients were divided into 1 of 2 groups, according to the circumstances that led to their initial diagnosis: (1) IPF was diagnosed incidentally, or (2) IPF was diagnosed nonincidentally when a patient was seen at the hospital for respiratory symptoms.

Pulmonary function tests obtained within 1 year from the date of IPF diagnosis and during the stable phase of the disease were assessed as baseline values. Baseline clinical characteristics, including sex, age, BMI, smoking status, and routine blood test results, were evaluated. Further, the level of serum Krebs von der Lungen-6—a diagnostic and prognostic biomarker in IPF—was evaluated as well.

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Most patients with IPF exhibit symptoms of cough and/or dyspnea on exertion at the time of diagnosis. In those who are diagnosed incidentally, however, minimal or no respiratory symptoms are observed, and the clinical features of these individuals remain unknown.

In the current study, among a total of 107 individuals with newly diagnosed IPF, 32.7% (35 of 107) of them were diagnosed with IPF incidentally, which included 18 persons undergoing annual health checkups and 17 being evaluated for other medical issues.

Study findings showed that the median survival from the time of diagnosis was 4.9 years among the 35 patients who were diagnosed with IPF incidentally—a rate that was comparable to the median survival of 3.9 years reported in those who were diagnosed nonincidentally (log-rank analysis, P =.13). BMI was the sole independent predictor of survival (hazard ratio, 0.78; 95% CI, 0.65 to 0.93; P =.006) in patients who were diagnosed incidentally.

“Identifying patients during the earliest stage of IPF, particularly those with a low BMI, is warranted.” Such individuals would then have the opportunity to be treated with antifibrotic agents (ie, pirfenidone or nintedanib),” the researchers said.


Yamazaki R, Nishiyama O, Yoshikawa K, Tohda Y, Matsumoto H. Outcome of patients who were
incidentally diagnosed with idiopathic pulmonary fibrosis: how early in the disease should we identify
Respir Med. Published online July 14, 2022. doi:10.1016/j.rmed.2022.106933