Inspiratory Crackles in Idiopathic Pulmonary Fibrosis – Friend or Foe for Early Diagnosis?

Background: Velcro crackles (VCR) are frequent in idiopathic pulmonary fibrosis (IPF) patients and have been advocated as a tool for early diagnosis. We assessed their association with clinical features, progression, and survival in the European MultiPartner IPF Registry (EMPIRE). Methods: Clinical, imaging, and pulmonary function data were collected at baseline and followed up at least every six months. Cross-sectional analyses of baseline characteristics were performed for all and separately for incident IPF patients diagnosed within 6 months before inclusion. Progression-free (PFS) and overall survival (OS) were calculated by Kaplan–Meier estimates, progression was defined using different thresholds of FVC and DLCO decline, lung transplantation, and death. Annual FVC decline was calculated using a restricted maximum likelihood estimation based on a random slope and intercept model. Results: Of 4583 IPF patients (71% men, median age 70 (IQR 64–75)), 89% had VCR at enrollment. Patients with VCR were older, had a longer symptom duration and a higher prevalence of exertional dyspnea, cough, and finger clubbing. Also, they presented with lower FVC and DLCO, with a higher GAP stage, and more frequently had a definite usual interstitial pneumonia pattern on computed tomography. Neither PFS nor OS differed significantly according to presence of VCR in all and in incident patients. Adjusted FVC decline rate was significantly higher in all patients with velcro crackles (-0.102mL (95% CI -0.113; -0.091) vs. -0.056mL (-0.09; -0.023), p = 0.011). Conclusions: Most patients in EMPIRE presented with VCR and patients without VCR had less severe functional impairment and a shorter symptom duration. This supports the current role of auscultation as a primary care diagnostic tool but may challenge its alleged role in early diagnosis of IPF.