A systematic review of discharge coding accuracy

Background The aim of the study was to review systematically the literature measuring the accuracy of routine UK hospital statistics that classify pat ients on discharge. Methods A systematic review was carried out of studies comparing routine di scharge statistics about an episode of hospital care with the original medi cal record. Dual quality assessment and extraction was completed for includ ed studies. Qualitative and descriptive analyses were undertaken. Additiona l comparisons of factors that could potentially introduce systematic variat ion in coding accuracy were also undertaken. Results Thirty studies were identified, of which 21 were included in the re view. Twelve of these were conducted in England and Wales, and nine in Scot land. The majority assessed the accuracy of a single diagnosis, or selectio n of diagnoses in a limited range of hospital settings. The median coding a ccuracy rates were 91 per cent for diagnostic codes and 69.5 per cent for o peration or procedure codes in studies in England or Wales; 82 per cent for diagnostic codes and 98 per cent for operation or procedure codes in Scott ish studies. There were no significant differences in coding accuracy over time or in the type or rarity of the codes being assessed. Accuracy rates w ere higher for ICD7 codes (median 96.5 per cent) than for ICD8 (median 87 p er cent) or ICD9 (median 77 per cent). Conclusions Coding accuracy on average is high in the United Kingdom, espec ially for operations and procedures. However, policy-makers, planners and r esearchers need to recognize and account for the degree of inaccuracy in ro utine hospital information statistics. Further research is needed into meth ods of improving and maintaining coding accuracy.