Objectives: To estimate the extent, nature and consequences of adverse events in a large National Health Service (NHS) hospital, and to evaluate the reliability of a two-stage casenote review method in identifying adverse events.

Design: A two-stage structured retrospective patient casenote review.

Setting: A large NHS hospital in England.

Population: A random sample of 1006 hospital admissions between January and May 2004: surgery (n = 311), general medicine (n = 251), elderly (n = 184), orthopaedics (n = 131), urology (n = 61) and three other specialties (n = 68).

Main outcome measures: Proportion of admissions with adverse events, the proportion of preventable adverse events, and the types and consequences of adverse events.

Results: 8.7% (n = 87) of the 1006 admissions had at least one adverse event (95% CI 7.0% to 10.4%), of which 31% (n = 27) were preventable. 15% of adverse events led to impairment or disability which lasted more than 6 months and another 10% contributed to patient death. Adverse events led to a mean increased length of stay of 8 days (95% CI 6.5 to 9). The sensitivity of the screening criteria in identifying adverse events was 92% (95% CI 87% to 96%) and the specificity was 62% (95% CI 53% to 71%). Inter-rater reliability for determination of adverse events was good (κ = 0.64), but for the assessment of preventability it was only moderate (κ = 0.44).

Conclusion: This study confirms that adverse events are common, serious and potentially preventable source of harm to patients in NHS hospitals. The accuracy and reliability of a structured two-stage casenote review in identifying adverse events in the UK was confirmed.

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Extent, nature and consequences of adverse events: results of a retrospective casenote review in a large NHS hospital

Background: Limited data are available on adverse events among children admitted to hospital. The Canadian Paediatric Adverse Events Study was done to describe the epidemiology of adverse events among children in hospital in Canada. Methods: We performed a 2-stage medical record review at 8 academic pediatric centres and 14 community hospitals in Canada. We reviewed charts from patients admitted from April 2008 through March 2009, evenly distributed across 4 age groups (0 to 28 d; 29 to 365 d; > 1 to 5 yr and > 5 to 18 yr). In stage 1, nurses and health records personnel who had received training in the use of the Canadian Paediatric Trigger Tool reviewed medical records to detect triggers for possible adverse events. In stage 2, physicians reviewed the charts identified as having triggers and described the adverse events. Results: A total of 3669 children were admitted to hospital during the study period. The weighted rate of adverse events was 9.2%. Adverse events were more frequent in academic pediatric centres than in community hospitals (adjusted odds ratio [OR] 2.98, 95% confidence interval [CI] 1.65–5.39). The incidence of preventable adverse events was not significantly different between types of hospital, but nonpreventable adverse events were more common in academic pediatric centres (adjusted OR 4.39, 95% CI 2.08–9.27). Surgical events predominated overall and occurred more frequently in academic pediatric centres than in community hospitals (37.2% v. 21.5%, relative risk [RR] 1.7, 95% CI 1.0–3.1), whereas events associated with diagnostic errors were significantly less frequent (11.1% v. 23.1%, RR 0.5, 95% CI 0.2–0.9). Interpretation: More children have adverse events in academic pediatric centres than in community hospitals; however, adverse events in the former are less likely to be preventable. There are many opportunities to reduce harm affecting children in hospital in Canada, particularly related to surgery, intensive care and diagnostic error.

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Adverse events among children in Canadian hospitals: the Canadian Paediatric Adverse Events Study

Background: Adverse drug events (ADEs) are an important problem in all hospitalized patients as these events represent medication-related patient harm. Few epidemiologic data exist regarding ADEs in the pediatric inpatient setting and, in particular, the economic impact of such ADEs upon the healthcare sector.

Incidence, preventability, and impact of Adverse Drug Events (ADEs) and potential ADEs in hospitalized children in New Zealand: a prospective observational cohort study.

To identify a risk profile for harmful medication errors in the neonatal intensive care unit (NICU). A retrospective cross-sectional study on NICU medication error reports submitted to MEDMARX between 1 January 1999, and 31 December 2005. The Rao–Scott modified χ2 test was used for analysis. 6749 NICU medication error reports were submitted by 163 health-care facilities. Administering errors accounted for approximately one half of errors, and human factors were the most frequently cited cause of error. Patient age was not associated with an increased likelihood of an error being harmful (P=0.11). Error reports involving Institute for Safe Medication Practices (ISMP) High-Alert Medications, occurring in the prescribing phase of medication processing, or involving equipment/delivery device failures were more likely to be harmful (P⩽0.05). Risk factors for harmful medication error reports include use of ISMP High-Alert Medications, the prescribing phase of the medication use process, and failure of equipment/delivery devices.

NICU medication errors: identifying a risk profile for medication errors in the neonatal intensive care unit

The inter-rater agreement of retrospective assessments of adverse events does not improve with two reviewers per patient record

Background: In medication safety research studies medication related events are often classified by type, seriousness, and degree of preventability, but there is currently no universally reliable “gold standard” approach. The reliability (reproducibility) of this process is important as the targeting of prevention strategies is often based on specific categories of event. The aim of this study was to determine the reliability of reviewer judgements regarding classification of paediatric inpatient medication related events.

Methods: Three health professionals independently reviewed suspected medication related events and classified them by type (adverse drug event (ADE), potential ADE, medication error, rule violation, or other event). ADEs and potential ADEs were then rated according to seriousness of patient injury using a seven point scale and preventability using a decision algorithm and a six point scale. Inter- and intra-rater reliabilities were calculated using the kappa (κ) statistic.

Results: Agreement between all three reviewers regarding event type ranged from “slight” for potential ADEs (κ = 0.20, 95% CI 0.00 to 0.40) to “substantial” agreement for the presence of an ADE (κ = 0.73, 95% CI 0.69 to 0.77). Agreement ranged from “slight” (κ = 0.06, 95% CI 0.02 to 0.10) to “fair” (κ = 0.34, 95% CI 0.30 to 0.38) for seriousness classifications but, by collapsing the seven categories into serious versus not serious, “moderate” agreement was found (κ = 0.50, 95% CI 0.46 to 0.54). For preventability decision, overall agreement was “fair” (κ = 0.37, 95% CI 0.33 to 0.41) but “moderate” for not preventable events (κ = 0.47, 95% CI 0.43 to 0.51).

Conclusion: Trained reviewers can reliably assess paediatric inpatient medication related events for the presence of an ADE and for its seriousness. Assessments of preventability appeared to be a more difficult judgement in children and approaches that improve reliability would be useful.

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S M Williams

Papers

Inter- and intra-rater reliability for classification of medication related events in paediatric inpatients.