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About Sickkids
About SickKids

Felix Ratjen, MD, FRCP(C)

The Hospital for Sick Children
Division Chief
Respiratory Medicine

Research Institute
Head and Senior Scientist
Translational Medicine

University of Toronto

Chair Positions
The Hospital for Sick Children
H.E. Seller's Chair in Cystic Fibrosis

Phone: 416-813-6167
Fax: 416-813-6246
Email: felix.ratjen@sickkids.ca

Brief Biography

Dr. Felix Ratjen is the Division Chief of Paediatric Respiratory Medicine at The Hospital for Sick Children, Professor of Paediatrics at The University of Toronto, and Senior Scientist at the Research Institute in the Translational Medicine research program.  He is co-leading the CF centre at SickKids and Medical Director of the Clinical Research Unit.

Dr. Ratjen completed a majority of his medical education in Germany, along with a research fellowship at the Children's Hospital in Boston. He subsequently worked at the University of Essen, where he was appointed Deputy Chief of the Department of Paediatrics in 1998 and Professor of Paediatrics in 2001. Until 2005 he was the chief executive of the scientific board of the German CF foundation before relocating in Canada in the same year. He is an the organizing committees of the major respiratory meetings (American Thoracic Society, European Respiratory Society and the North American CF conference), works on multiple grant review panels is  a member of the several editorial boards including the American Journal of Respiratory and Critical Care Medicine, Thorax, Pediatric Pulmonology and the Journal of Cystic Fibrosis.

Research Interests

Dr. Ratjen is conducting multiple clinical trials addressing cystic fibrosis lung disease including new therapeutic strategies to target the underlying defect, treatment of airway infections such as first infection with Pseudomonas aeruginosa, airway inflammation and other important aspects of the disease. While some of these studies are single centre studies within the CF centre at SickKids or in collaboration with the adult centre at St. Michael’s Hospital, many of them include both national and international collaborations with centres in Canada, the US, Europe and Australia. In addition, he is involved in developing and validating new outcome measures to quantify important aspects of CF  lung disease that can be utilized in clinical trials. He also studies other lung diseases and over the recent years has developed an interest in the clinical evaluation of Hereditary Hemorrhagic Telangiectasia (HHT), for which he is leading one of the largest dedicated pediatric clinics.  

Lab website


Stenotrophomonas Maltophilia in Cystic Fibrosis: Serologic Response and Effect on Lung Disease.
Waters V, Yau Y, Prasad S, Lu A, Atenafu E, Crandall I, Tom S, Tullis E, Ratjen F.
Am J Respir Crit Care Med. 2010 Oct 1. [Epub ahead of print]

Hypertonic saline improves the LCI in paediatric patients with CF with normal lung function.
Amin R, Subbarao P, Jabar A, Balkovec S, Jensen R, Kerrigan S, Gustafsson P, Ratjen F.
Thorax. 2010 May;65(5):379-83.

Effect of azithromycin on pulmonary function in patients with cystic fibrosis uninfected with Pseudomonas aeruginosa: a randomized controlled trial.
Saiman L, Anstead M, Mayer-Hamblett N, Lands LC, Kloster M, Hocevar-Trnka J, Goss CH, Rose LM, Burns JL, Marshall BC, Ratjen F; AZ0004 Azithromycin Study Group. JAMA. 2010 May 5;303(17):1707-15.

Treatment of early Pseudomonas aeruginosa infection in patients with cystic fibrosis: the ELITE trial.
Ratjen F, Munck A, Kho P, Angyalosi G; ELITE Study Group.
Thorax. 2010 Apr;65(4):286-91. Epub 2009 Dec 8.

The effect of chronic infection with Aspergillus fumigatus on lung function and hospitalization in patients with cystic fibrosis.
Amin R, Dupuis A, Aaron SD, Ratjen F. Chest. 2010 Jan;137(1):171-6. 

Screening for pulmonary and cerebral arteriovenous malformations in children with hereditary haemorrhagic telangiectasia.
Al-Saleh S, Mei-Zahav M, Faughnan ME, MacLusky IB, Carpenter S, Letarte M, Ratjen F.
Eur Respir J. 2009 Oct;34(4):875-81

A multicenter, randomized, double-blind, placebo-controlled trial to evaluate the metabolic and respiratory effects of growth hormone in children with cystic fibrosis.
Schnabel D, Grasemann C, Staab D, Wollmann H, Ratjen F; German Cystic Fibrosis Growth Hormone Study Group.
Pediatrics. 2007 Jun;119(6):e1230-8.

Inhaled L-arginine improves exhaled nitric oxide and pulmonary function in patients with cystic fibrosis.
Grasemann H, Kurtz F, Ratjen F.
Am J Respir Crit Care Med. 2006 Jul 15;174(2):208-12.

Increased arginase activity in cystic fibrosis airways.
Grasemann H, Schwiertz R, Matthiesen S, Racké K, Ratjen F.
Am J Respir Crit Care Med. 2005 Dec 15;172(12):1523-8.