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The Clinical Course of Patients with Idiopathic Pulmonary Fibrosis

Martinez FJ, Safrin S, Weycker D, et al, for the IPF Study Group. Ann Intern Med. 2005;142:963-967.

Discussion

  • There are few prospective data regarding the natural history of idiopathic pulmonary fibrosis (IPF), the most common of the idiopathic interstitial pneumonias.
  • To describe the clinical course and cause of death in a cohort of patients (N = 168) with mild to moderate IPF, Martinez and colleagues analyzed data from the placebo group of a recently completed randomized, double-blind study of interferon gamma-1b.1
  • Patients were followed at 12-week intervals over a median study period of 76 weeks. Assessments included physiologic variables, measures of dyspnea, hospitalizations, disease progression, and causes of death. Information was collected through patient interview and examination, and both patient and physician questionnaires.

Results:

  • The clinical course of patients with mild to moderate IPF was characterized by:
    • minimal detected physiologic decline (as measured by diffusing capacity of carbon monoxide, forced vital capacity, and alveolar-arterial oxygen gradient) or worsening of dyspnea in patients who survived to week 72
    • frequent hospitalizations (38 patients had 57 hospitalizations for respiratory disorders), most commonly (33%) for presumed infection
    • rapid progression of lung disease in almost 50% of patients who died of an IPF-associated cause, even in the absence of significant change in physiologic variables
  • IPF was a main or related cause of death in 32 of the 36 patients who died. Of these, 41% occurred within 4 weeks of the onset of new or worsening symptoms.
  • Limitations of this study include the retrospective method of data collection, the lack of standardized criteria for hospitalization and acute decompensation, and a lack of knowledge regarding the generalizability of the results.

Implications/Recommendations:

  • Since IPF patients may experience sudden and precipitous declines (rather than gradual progression), more frequent evaluations may be warranted.
  • Clinical signs and symptoms that may alert the clinician to an impending decompensation include:
    • Rapid progression of dyspnea (over 1 month or less)
    • New, diffuse opacities on chest radiography
    • Worsening hypoxemia
    • Rapid development of respiratory failure in the absence of alternative diagnoses or infection
    • Acute alveolar injury with or without hyaline membrane formation
    • A concomitant diagnosis of cor pulmonale, respiratory distress syndrome, or pneumonia
  • Early referral for lung transplantation may be advisable.

Reference

  1. Raghu G, Brown KK, Bradford WZ, et al. A placebo-controlled trial of interferon gamma-1b in patients with idiopathic pulmonary fibrosis. N Engl J Med. 2004;350:125-133.

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