<qa>  What is the Swedish National Patient Registry hosted by?The Swedish National Patient Registry NPR is hosted by the Swedish Agency of Health and Welfare and contains all patient contacts within Sweden with a coverage of 90 for orthopaedic diagnoses. Registered are main diagnosis and co-morbidity using the ICD-9 code until 1996 and from 1997 onward ICD-10 codes. Treatment is coded since 1996 using the Swedish classification of surgical procedures. Furthermore, information on hospitalisation time is available from the registry. 