title: Reconciliation of international administrative coding systems for comparison of colorectal surgery outcome.
abstract: OBJECTIVE
  Significant variation in colorectal surgery outcomes exists between different countries. Better understanding of the sources of variable outcomes using administrative data requires alignment of differing clinical coding systems. We aimed to map similar diagnoses and procedures across administrative coding systems used in different countries.
  
  
  METHODS
  Administrative data were collected in a central database as part of the Global Comparators (GC) Project. In order to unify these data, a systematic translation of diagnostic and procedural codes was undertaken. Codes for colorectal diagnoses, resections, operative complications and reoperative interventions were mapped across the respective national healthcare administrative coding systems. Discharge data from January 2006 to June 2011 for patients who had undergone colorectal surgical resections were analysed to generate risk-adjusted models for mortality, length of stay, readmissions and reoperations.
  
  
  RESULTS
  In all, 52 544 case records were collated from 31 institutions in five countries. Mapping of all the coding systems was achieved so that diagnosis and procedures from the participant countries could be compared. Using the aligned coding systems to develop risk-adjusted models, the 30-day mortality rate for colorectal surgery was 3.95% (95% CI 0.86-7.54), the 30-day readmission rate was 11.05% (5.67-17.61), the 28-day reoperation rate was 6.13% (3.68-9.66) and the mean length of stay was 14 (7.65-46.76) days.
  
  
  CONCLUSIONS
  The linkage of international hospital administrative data that we developed enabled comparison of documented surgical outcomes between countries. This methodology may facilitate international benchmarking.
authors.affiliation: Department of Surgery and Cancer, Imperial College, St Mary's Hospital, London, UK.
authors.forename: A
authors.initials: A
authors.lastname: Munasinghe
authors.forename: D
authors.initials: D
authors.lastname: Chang
authors.forename: R
authors.initials: R
authors.lastname: Mamidanna
authors.forename: S
authors.initials: S
authors.lastname: Middleton
authors.forename: M
authors.initials: M
authors.lastname: Joy
authors.forename: F
authors.initials: F
authors.lastname: Penninckx
authors.forename: A
authors.initials: A
authors.lastname: Darzi
authors.forename: E
authors.initials: E
authors.lastname: Livingston
authors.forename: O
authors.initials: O
authors.lastname: Faiz
mesh_terms: D019985:Benchmarking; D059019:Clinical Coding; D003110:Colonic Neoplasms / Q000601:surgery; D003625:Data Collection / Q000379:methods*; D013505:Digestive System Surgical Procedures / Q000009:adverse effects / Q000592:standards / Q000706:statistics & numerical data*; D004240:Diverticulum / Q000601:surgery; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000601:surgery; D007902:Length of Stay; D017063:Outcome Assessment, Health Care; D012004:Rectal Neoplasms / Q000601:surgery
keywords: International coding systems; colorectal surgery; international comparison; surgical outcome