[Positive predictive value of ICD-9-CM codes in hospital inpatient discharge abstract records, for identifying adverse events]

A retrospective study was conducted in the ambit of Risk Management research, in order to assess adverse events in patients hospitalised in hospitals in one Local Health Authority of the Piemonte region. Specifically, the aims of the study were to: evaluate the relative frequency of ICD-9-CM codes used to define adverse events, with respect to the total number of hospital discharge records submitted in 2003; identify true and false positives, by hospital chart review; estimate the positive predictive value (VPP) of the ICD-9-CM codes used, and determine, in each case, whether the adverse event had led to hospitalisation or if it had occurred during hospitalisation. Results show that the ICD-9-CM codes used effectively identify adverse events. In fact, the probability that an ICD-9-CM code will accurately identify an adverse event is 100% for codes in the 'Misadventures of surgical and medical care' category of adverse events, 62.8% for codes indicating 'Complications of medications (adverse drug events)' and 56.8% for the 'Complications of surgical or medical procedures' category. In most cases the adverse event had occurred prior to hospital admission.