Pharmacoeconomics 2006; 24 (10): 999-1009 ORIGINAL RESEARCH ARTICLE 1170-7690/06/0010-0999/$39.95/0  2006 Adis Data Information BV. All rights reserved. Hospitalisation Costs of Cystic Fibrosis Jonas Schrey¨ ogg, 1 Helge Hollmeyer, 2 Miriam Bluemel, 1 Doris Staab 2 and Reinhard Busse 1 1 Department of Health Care Management, WHO Collaborating Centre for Health Systems Research and Management, Faculty of Economics and Management, Berlin University of Technology, Berlin, Germany 2 Department of Paediatric Pneumology and Immunology, Charit´ e Medical School, Children’s Hospital, Berlin, Germany Objective: To calculate per-case hospital costs for patients with cystic fibrosis Abstract under routine conditions from a healthcare provider’s perspective; identify the impact of different cost categories; investigate whether cases with cystic fibrosis can be grouped into homogenous cost groups according to defined severity levels; and determine the value of specific factors as predictors of hospital cost varia- tions. Methods: All data were collected from cases (n = 131) admitted to an inpatient cystic fibrosis unit under routine conditions during a period of 6 months in 2004. All costs were calculated for the year 2004 and divided into categories with high and low impact on variation in hospitalisation costs between patients. Staff costs for patient care, laboratory costs and drug costs were defined as categories with high impact, thus the individual resource utilisation for each case was measured. Cost categories that were classified as having a low impact were measured as overhead costs. Cases were classified according to two different severity models; within each model, patients were classified according to three severity levels. The diagnosis-related model classifies patients with pulmonary hypertension and global respiratory insufficiency as having severe disease, patients with Pseudomonas aeruginosa as having moderate disease, and patients with no colonisation of the lungs as having mild disease. The lung-function-related model differentiates patients as having mild, moderate and severe disease when patients have forced expiratory volumes in 1 second (FEV1) that are ≥70%, between ≥40% and <70%, and <40%, respectively. Analysis of variance tests were performed to investigate the differences of mean costs between the groups. Ordinary least squares regression analysis was used to determine predictors for cost variation.