Inherent weaknesses of the current ICD coding system regarding idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most prevalent of the idiopathic interstitial pneumonias (IIPs). It carries an ominous prognosis with a median survival of 3 years. Its epidemiology is poorly described because of its rarity and lack of unanimity in diagnostic and coding practices [1]. However, during the last few years, significant improvement has been achieved in our understanding of the pathogenesis, diagnosis and management of IPF and IIP in general. This is reflected in the 2011 American Thoracic Society (ATS)/European Respiratory Society (ERS)/Japanese Respiratory Society/ALAT consensus statement on IPF [2] and the 2013 ATS/ERS update of the International Multidisciplinary Classification of the Idiopathic Interstitial Pneumonias [3]. To obtain a robust understanding of the epidemiology of IPF is important, especially as novel therapies are emerging. The International Classification of Disease (ICD) coding system represents a great opportunity to create such registries that will expand our knowledge on IPF epidemiology. However, under its current formation, the 10th edition (ICD-10) coding system has severe deficiencies regarding the accurate classification of IPF. ICD-10 does not adequately classify IPF