Authors' reply to Lin and colleagues.

1Department of Orthopaedics and Traumatology, University of Helsinki and Helsinki University Central Hospital, Helsinki, Finland; 2Department of Surgical Sciences, Section of Orthopaedics, Uppsala University, Uppsala, Sweden; 3Department of Hand Surgery, Tampere University Hospital, Tampere, Finland; 4Centre for Statistics in Medicine, Botnar Research Centre, University of Oxford, Oxford, UK; 5Departments of Anesthesiology, Pharmacology, and Therapeutics and Medicine, University of British Columbia, Vancouver, BC, Canada; 6Faculty of Pharmacy and Charles Perkins Centre, University of Sydney, Sydney, Australia; 7Drug Information Unit, Navarre Regional Health Service, Pamplona, Navarre, Spain; 8Department of Health, Government of Navarre, Pamplona, Navarre, Spain; 9UKK Institute for Health Promotion Research, Tampere, Finland