Representative case series from public hospital admissions 1998 I: drug and related therapeutic adverse events

Aims To examine a representative case series of drug and related therapeutic adverse events in New Zealand public hospitals with a view to assessing their occurrence, causation, patient impact and preventability. Methods An analysis was carried out on 192 drug and related therapeutic adverse events classified by reviewing physicians. These were identified from among 850 adverse events determined by two-stage retrospective review of a representative sample of 6579 medical records drawn from 13 public hospitals in 1998. Results One fifth of all adverse events were in the combined group, comprising drug (15.4%) and related therapeutic (7.3%) incidents. In comparison with other adverse events these incidents appeared to be more common among older patients, were less likely to have occurred in hospital, and had slightly less impact on patients. Cardiovascular drugs accounted for nearly half of drug events; poor infection management, by contrast, was the dominant factor among related therapeutic events, with problems in cardiovascular management also important. Inadequate monitoring and follow up of medication was identified as the most common reason for failure to prevent both drug and related therapeutic adverse events. Conclusions This study shows that morbidity related to medications is extensive. Drug-related adverse events are frequent and many are preventable. Better monitoring and more appropriate medication choice for individuals are the most common prevention strategies identified. The recently completed New Zealand Quality of Healthcare Study (NZQHS) examined 6579 medical records using two-stage retrospective review applied to a representative sample of hospital admissions for the calendar year 1998. The sample was drawn by systematic list selection, after the exclusion of specialist institutions, from 13 public hospitals providing acute care and with over 100 beds. The main aim was to quantify the impact of adverse outcomes of healthcare management in the New Zealand public hospital system. 1 The NZQHS reported that 12.9% of public hospital admissions were associated with an adverse event, 1 a rate that is similar to those recorded for Australia (16.6%) and the United Kingdom (10.8%) in comparable studies. 2,3 Half of these events in New Zealand were preventable and occurred inside hospital and, of these, 7.5% were associated with pharmacological treatment and 10.7% with therapy-related incidents. 4 The United States (US) report on the quality of care by the Institute of Medicine has raised international awareness of the incidence and effects of adverse drug events in hospitals, concluding that, although not all adverse drug events result in actual harm, those that do are costly. 5 Therefore, the principal objective of this paper is to assess