title: Individual FEV1 Trajectories Can Be Identified from a COPD Cohort.
abstract: We aim to make use of clinical spirometry data in order to identify individual COPD-patients with divergent trajectories of lung function over time.
  
  
  
  Hospital-based COPD cohort (N = 607) was followed on average 4.6 years. Each patient had a mean of 8.4 spirometries available. We used a Hierarchical Bayesian Model (HBM) to identify the individuals presenting constant trends in lung function.
  
  
  
  At a probability level of 95%, one third of the patients (180/607) presented rapidly declining FEV1 (mean -78 ml/year, 95% CI -73 to -83 ml) compared to that in the rest of the patients (mean -26 ml/year, 95% CI -23 to -29 ml, p ≤ 2.2 × 10(-16)). Constant improvement of FEV1 was very rare. The rapid decliners more frequently suffered from exacerbations measured by various outcome markers.
  
  
  
  Clinical data of unique patients can be utilized to identify diverging trajectories of FEV1 with a high probability. Frequent exacerbations were more prevalent in FEV1-decliners than in the rest of the patients. The result confirmed previously reported association between FEV1 decline and exacerbation rate and further suggested that in clinical practice HBM could improve the identification of high-risk individuals at early stages of the disease.
authors.affiliation: a Clinical Research Unit for Pulmonary Diseases and Division of Pulmonology , Helsinki University Central Hospital , Helsinki , Finland.
authors.forename: Jukka
authors.initials: J
authors.lastname: Koskela
authors.affiliation: a Clinical Research Unit for Pulmonary Diseases and Division of Pulmonology , Helsinki University Central Hospital , Helsinki , Finland.
authors.forename: Milla
authors.initials: M
authors.lastname: Katajisto
authors.affiliation: b CSC- IT Center for Science Ltd., Department of Information and Computer Science, Aalto University , Helsinki Institute for Information Technology (HIIT) , Helsinki , Finland.
authors.forename: Aleksi
authors.initials: A
authors.lastname: Kallio
authors.affiliation: c Division of Medicine, Dept. of Pulmonary Diseases and Clinical Allergology , Turku University Hospital and University of Turku , Turku , Finland.
authors.forename: Maritta
authors.initials: M
authors.lastname: Kilpeläinen
authors.affiliation: a Clinical Research Unit for Pulmonary Diseases and Division of Pulmonology , Helsinki University Central Hospital , Helsinki , Finland.
authors.forename: Ari
authors.initials: A
authors.lastname: Lindqvist
authors.affiliation: a Clinical Research Unit for Pulmonary Diseases and Division of Pulmonology , Helsinki University Central Hospital , Helsinki , Finland.|c Division of Medicine, Dept. of Pulmonary Diseases and Clinical Allergology , Turku University Hospital and University of Turku , Turku , Finland.
authors.forename: Tarja
authors.initials: T
authors.lastname: Laitinen
mesh_terms: D000368:Aged; D001499:Bayes Theorem; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012189:Retrospective Studies; D013147:Spirometry
keywords: COPD; FEV1 development; FEV1 slope; hierarchical Bayesian model; rapid decline