ACCURACY OF INJURY CODING IN VICTORIAN HOSPITAL MORBIDITY DATA

In Victoria injury surveillance data are drawn from hospital morbidity data. The accuracy and reliability of these data are often questioned . We aimed to ascertain the reliability of injury data in the Victoria n inpatient minimum database. A random sample of 546 public hospital s eparations with principal diagnosis ICD-9-CM codes 800-999 was selecte d from four metropolitan hospitals. Medical records were reviewed, and the hospital coding was compared with the record content. The frequen cy of error in any coding field was 73 per cent (349/480); of diagnosi s error, 61 per cent (292/480); of procedure error, 45 per cent (168/3 70); of error in the principal diagnosis, 19 per cent (93/480); and of error in external-cause codes (E-codes), 16 per cent (75/480). Ninety -four per cent of errors (87/93) in the principal diagnosis involved r ecoding within the same group of codes. Only 6 per cent (6/93) were re coded to principal diagnoses other than injury. Sixty-two per cent (18 1/292) were errors of omission of codes for comorbid conditions. Nearl y half the errors in the principal diagnosis were minor, involving the last two digits. E-codes were more complete than diagnosis codes. The best predictors of error in the principal diagnosis were greater leng th of stay, type of injury code (poisonings and toxic effects were ass ociated with lower error rates) and death as the outcome. While select ion of data from secondary diagnosis fields may not provide complete d ata, the use of the principal-diagnosis code and E-codes for injury su rveillance is feasible and reliable. The database is a valuable source of injury surveillance data, bearing in mind the limitations of coded hospital morbidity data.