Intended for healthcare professionals


Comparison of three methods for estimating rates of adverse events and rates of preventable adverse events in acute care hospitals

BMJ 2004; 328 doi: (Published 22 January 2004) Cite this as: BMJ 2004;328:199
  1. Philippe Michel, medical director (philippe.michel{at},
  2. Jean Luc Quenon, epidemiologist1,
  3. Anne Marie de Sarasqueta, public health nurse1,
  4. Olivier Scemama, epidemiologist1
  1. 1Comité de Coordination de l'Evaluation Clinique et de la Qualité en Aquitaine, Hôpital Xavier Arnozan, 33604 Pessac, France
  1. Correspondence to: P Michel
  • Accepted 16 October 2003


Objectives To compare the effectiveness, reliability, and acceptability of estimating rates of adverse events and rates of preventable adverse events using three methods: cross sectional (data gathered in one day), prospective (data gathered during hospital stay), and retrospective (review of medical records).

Design Independent assessment of three methods applied to one sample.

Setting 37 wards in seven hospitals (three public, four private) in southwestern France.

Participants 778 patients: medical (n = 278), surgical (n = 263), and obstetric (n = 237).

Main outcome measures The main outcome measures were the proportion of cases (patients with at least one adverse event) identified by each method compared with a reference list of cases confirmed by ward staffand the proportion of preventable cases (patients with at least one preventable adverse event). Secondary outcome measures were inter-rater reliability of screening and identification, perceived workload, and face validity of results.

Results The prospective and retrospective methods identified similar numbers of medical and surgical cases (70% and 66% of the total, respectively) but the prospective method identified more preventable cases (64% and 40%, respectively), had good reliability for identification (κ= 0.83), represented an acceptable workload, and had higher face validity. The cross sectional method showed a large number of false positives and identified none of the most serious adverse events. None of the methods was appropriate for obstetrics.

Conclusion The prospective method of data collection may be more appropriate for epidemiological studies that aim to convince clinical teams that their errors contribute significantly to adverse events, to study organisational and human factors, and to assess the impact of risk reduction programmes.


  • Contributors PM designed the project, wrote the original research proposal, and managed the project. PM and JLQ supervised the physician investigators and performed data analysis. AMS supervised the nurse and midwife investigators and was responsible for data quality control. OS did the initial literature analysis and translated the English review form into our questionnaires. PM and JLQ will act as guarantors for the paper.

  • Funding Financial support was provided by the Ministry of Health (Direction de la Recherche, des Etudes, de l'Evaluation et des Statistiques).

  • Conflict of interest None.

  • Competing interest None declared.

  • Ethical approval Not required.

  • Accepted 16 October 2003
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