Criteria for adverse events

Table A

Table B
 
 

Criteria for adverse events

An adverse event is "an unintended injury caused by medical management rather than by the disease process and which is sufficiently serious to lead to prolongation of hospitalisation or to temporary or permanent impairment or disability to the patient at time of discharge"

• Medical management includes both the actions of an individual member of staff or the overall health care system.

• Medical management includes acts of omission (for example, failure to diagnose or treat) and commission (for example, incorrect treatment).

• Causation of adverse event by medical management was judged on a six point scale, where 1 indicates "virtually no evidence for management causation" and 6 indicates "virtually certain evidence for management causation." Only adverse events with a score of 4 or higher, requiring evidence that causation is more likely than not, are reported in the results.

• Adverse events may or may not be preventable; the judgment is separate from that of causation. Preventability was also judged on a six point scale, with only those adverse events scoring 4 or higher being considered preventable.

• Injury may result from intervention or from failure to intervene. Although this is not always made clear, injuries that come about from failure to arrest the disease process are also included provided that standard care would clearly have prevented the injury.

• The injury has to be unintended, since injury can occur deliberately and with good reason (for example, amputation).

• Adverse events include recognised complications, which were judged as leading to harm but being of low preventability.

Operationalisation of adverse event criteria

The review form is structured in such a way that the clinician was obliged to make specific judgments about such issues as causation before making a final decision on the presence or absence of an adverse event. The definition of an adverse event is specified in the questionnaire and referred to during each review. Many of the criteria above are essentially clarifications of the basic definition designed to overcome common problems and ensure a consistent way of working. For instance, clinicians may be reluctant to include known complications as adverse events. In fact, the definition requires that they be included, but clinicians would specify low preventability to indicate that a certain level of complications is to be expected.

In this preliminary study we primarily aimed to follow the methods of previous studies and have used the same broad definition. In the light of our experience, and of further analysis of Australian data, we believe it would now be feasible to compile a list of some of the more important adverse events before a future study and produce standardised criteria for at least a proportion of specified adverse events.

Judgments of preventability

An adverse event was considered preventable if the reviewer judged that it would not have occurred if the patient had received ordinary standards of NHS care, appropriate for the time of the study (1998). For instance omission of prophylactic antibiotics or anticoagulants specified in a department protocol. As specified above a score of 4 or above on a six point scale was required for an adverse event to be identified as preventable.

Reliability and validity of adverse event judgments

For a full discussion of sensitivity and specificity issues, and data from reliability studies, see Brennan TA, Localio AR, Laird NL. Reliability and validity of judgement concerning adverse events suffered by hospitalised patients. Med Care 1989;27:1148-58.
 
 

Table A Number of records screened and number of adverse events by specialty and age

     

    Age
    No of records screened
    No of patients with adverse events
    Total No of adverse events 
    Preventable adverse events 
    General medicine
    16-29
    27
    2
    2
    2
     

    30-44
    50
    3
    3
    2
    mean = 56 years
    45-64
    80
    4
    4
    2
    median = 61 years
    ³ 65
    112
    15
    16
    13
    range = 17-97
    Missing
    4
    0
     

     

     

    Total
    273
    24
    25
    19
     

    General surgery
    16-29
    43
    2
    2
    1
     

    30-44
    72
    6
    7
    3
    mean = 53 years
    45-64
    72
    14
    16
    7
    median = 53 years
    ³65
    103
    19
    22
    9
    range = 16-94
    Total
    290
    41
    47
    20
     

    Obstetrics
    16-29
    103
    5
    5
    3
     

    30-44
    64
    2
    2
    2
    mean = 28 years
    45-64
    C
     

     

     

    median = 28 years
    Missing
    6
    0
     

     

    range = 17-41
    Total
    173
    7
    7
    5
     

    Orthopaedics
    16-29
    36
    1
    1
    0
     

    30-44
    52
    2
    2
    0
    mean = 58 years
    45-64
    63
    7
    7
    0
    median = 60.5 years
    ³65
    127
    28
    30
    13
    range = 18-102
    Total
    278
    38
    40
    13
     

    Total
    16-29
    209
    10
    10
    6
     

    30-44
    238
    13
    14
    7
    mean = 51 years
    45-64
    215
    25
    27
    9
    median = 50 years
    65+
    342
    62
    68
    35
    range = 16-102
    Missing
    10
    0
     

     

     

    Total
    1014
    110
    119
    57

 

Table B Characteristics of cases who did and did not have adverse event

    Specialty
    No of cases
    Mean (range) length of stay (days)
    % of women 
    Age (years)
    Median (mean)
    Range
    Adverse event
    General medicine 
    24
    17 (1-46)
    50
    68.5 (63)
    24-97
    General surgery 
    41
    22 (2-193)
    49
    62 (60)
    18-90
    Obstetrics 
    7
    6 (2-11)
    100
    27 (27)
    20-34
    Orthopaedics 
    38
    23 (2-73)
    68
    77.5 (74)
    24-102
    All specialties 
    110
    20 (1-193)
    59
    68.5 (63)
    18-102
    No adverse event
    General medicine 
    249
    11 (1-149)
    44
    61 (56)
    17-97
    General surgery 
    249
    8 (2-113)
    53
    51 (52)
    16-94
    Obstetrics 
    166
    4 (1-34)
    100
    28 (28)
    17-41
    Orthopaedics 
    240
    11 (2-124)
    57
    56 (56)
    18-98
    All specialties 
    904
    9 (1-149)
    60
    47.5 (50)
    16-98

Rapid Responses:

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R C Bosanquet
bmj.com, 4 Mar 2001 [Full text]
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bmj.com, 8 Mar 2001 [Full text]
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