Cluster analysis based clinical profiling of Idiopathic Pulmonary Fibrosis patients according to comorbidities evident prior to diagnosis: a single-center observational study.

BACKGROUND:The characterization and clinical profiling of people affected by Idiopathic Pulmonary Fibrosis (IPF), based on clinical events occurring prior to the diagnosis of the fibrotic disease, may facilitate the understanding of events and comorbidities that occur before the diagnosis of IPF and aid in identifying patients at an earlier stage of the disease. METHODS:In this observational study, a cohort of 96 patients, obtained from a community-based pulmonary clinic, were studied retrospectively. These patients were diagnosed with IPF between January 2008 and November 2016, based on findings on lung biopsy and/or high-resolution CT. Using clinical data obtained within the five years before diagnosis and the two-step method of cluster analysis, patients were assigned to one of four groups. The distribution of clinical characteristics and comorbidities present prior to diagnosis was analyzed among the clusters. RESULTS:Cluster 1 is composed of male patients, smokers, with ischemic heart disease. Cluster 2 is composed of male patients, smokers with dyspnea at rest, dry cough and prevalent emphysema. Cluster 3 is composed of male patients without other significant comorbidities, half of whom had dyspnea at exertion. Cluster 4 includes female patients only, most of whom never-smokers and the largest portion of patients with hypothyroidism. The majority of patients had basal end-inspiratory crackles at time of diagnosis, equally distributed among clusters. CONCLUSION:Different clinical phenotypes of IPF emerge years before time of diagnosis and if confirmed in larger cohorts may help in forming diagnostic algorithms that would allow earlier diagnosis of IPF.