title: The H.O.U.S.E. classification: a novel endoscopic retrograde cholangiopancreatography (ERCP) complexity grading scale.
abstract: BACKGROUND
  Endoscopic retrograde cholangiopancreatography (ERCP) is a technically challenging endoscopic procedure, harboring a wide range of complexities within every single investigation. Classifications of the complexity of ERCP have been presented, but do not include modern endoscopic treatment modalities. In order to be able to target resources and compare the results of different endoscopic centers, a new complexity grading system for ERCP is warranted. This study launches a new complexity grading scale for ERCP-the H.O.U.S.E.-classification.
  
  
  METHODS
  The medical record of every patient undergoing ERCP 2009-2011 at the Karolinska University Hospital was reviewed, regarding the complexity of the procedure, and categorized into one out of three-grades in the HOUSE classification system, and concomitantly graded according to the Cotton grading system. All ERCP-procedures were also registered in the Swedish registry for gallstone surgery and ERCP (GallRiks) and correlations between the grading systems and procedure related variables as well as outcomes were made.
  
  
  RESULTS
  Between 2009 and 2011, 2185 ERCPs were performed at the Karolinska University Hospital, Huddinge. One thousand nine hundred fifty-four of those were index-ERCPs. Another 23 patients were excluded due to lack of postoperative complication registrations, leaving 1931 ERCP procedures to be analyzed. The procedure times were 40 ± 0.7, 65 ± 1.5 and 106 ± 3.2 min, respectively (HOUSE 1-3). The corresponding pancreatitis rates were 3.4, 7.0 and 6.8% and the postoperative complication rates 11.1, 15.7 and 12.8%, respectively.
  
  
  CONCLUSIONS
  The HOUSE-classification is a novel grading scale for ERCP-complexity. The system can be implemented in clinical practice to allocate resources and allow the comparisons of results between different endoscopic centers. Further studies are warranted to further sharpen this instruments validitity and general clinical relevance.
authors.affiliation: Division of Surgery, CLINTEC, Karolinska Institutet, Stockholm, Sweden. greger.olsson@ki.se.|Department of Surgery, Ryhov County Hospital, Jönköping, S-551 85, Sweden. greger.olsson@ki.se.
authors.forename: Greger
authors.initials: G
authors.lastname: Olsson
authors.affiliation: Division of Surgery, CLINTEC, Karolinska Institutet, Stockholm, Sweden.|Center for Digestive Diseases, Karolinska University Hospital, Huddinge, Stockholm, S-141 86, Sweden.
authors.forename: Urban
authors.initials: U
authors.lastname: Arnelo
authors.affiliation: Division of Surgery, CLINTEC, Karolinska Institutet, Stockholm, Sweden.|Center for Digestive Diseases, Karolinska University Hospital, Huddinge, Stockholm, S-141 86, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Swahn
authors.affiliation: Division of Surgery, CLINTEC, Karolinska Institutet, Stockholm, Sweden.|Center for Digestive Diseases, Karolinska University Hospital, Huddinge, Stockholm, S-141 86, Sweden.
authors.forename: Björn
authors.initials: B
authors.lastname: Törnqvist
authors.affiliation: Division of Surgery, CLINTEC, Karolinska Institutet, Stockholm, Sweden.|Center for Digestive Diseases, Karolinska University Hospital, Huddinge, Stockholm, S-141 86, Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Lundell
authors.affiliation: Division of Surgery, CLINTEC, Karolinska Institutet, Stockholm, Sweden. lars.enochsson@ki.se.|Center for Digestive Diseases, Karolinska University Hospital, Huddinge, Stockholm, S-141 86, Sweden. lars.enochsson@ki.se.
authors.forename: Lars
authors.identifier: http://orcid.org/0000-0002-1930-654X
authors.initials: L
authors.lastname: Enochsson
mesh_terms: D000368:Aged; D002760:Cholangiopancreatography, Endoscopic Retrograde / Q000009:adverse effects / Q000145:classification*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D017063:Outcome Assessment, Health Care / Q000145:classification*; D010195:Pancreatitis / Q000453:epidemiology / Q000209:etiology; D011183:Postoperative Complications / Q000453:epidemiology / Q000209:etiology; D012042:Registries; D013548:Sweden / Q000453:epidemiology
keywords: Complications; ERCP; Pancreatitis