Urgency and priority for cardiac surgery: a clinical judgment analysis

British Medical Journal, March 21, 1998 by F. Kee, P. McDonald, J.R. Kirwan, C.C. Patterson, A.H.G. Love

The Clinical Standards Advisory Group has expressed concern over the lack of clear criteria with which to accord priority to patients awaiting coronary artery bypass surgery.[1] Until recently, the most notable research on what determines "urgency" was to be found in reports from Ontario which point to variations between doctors and institutions in the criteria they use to place patients in a queue.[2-4] Earlier this year the New Zealand National Advisory Committee on Health published its findings on the impact that some social factors, such as the threat to independence, the care of dependents, or the patient's ability to work, might have on decisions related to priority.[5]

The influence of demographic or lifestyle factors, such as age or smoking habit, on waiting list priority has been debated prominently in the United Kingdom.[6 7] Doctors may take an individual view of the probable effectiveness of revascularisation in some patients (for example, smokers compared with non-smokers). However, neither the perceived efficacy of the procedure nor the distinction between "urgency" (the speed required to intervene to obtain a desired clinical outcome) and "priority" (the relative position on a surgical waiting list) has yet been investigated. Doctors might agree that a patient who smokes needs urgent intervention but disagree over the priority this patient should be accorded on a waiting list for surgery.

In response to the Clinical Standards Advisory Group report, a regional workshop sponsored by the Northern Ireland Clinical Resource Efficiency Support Team was convened in the spring of 1996 to address these issues. Two main research questions were:

* Do clinicians pay attention to demographic and lifestyle factors when making urgency and priority judgments?

* Do disagreements between clinicians arise out of differences in how they attend to clinical and demographic factors in arriving at these judgments?

Methods

The key task which participants ("judges") undertook before the workshop was an appraisal of "paper patients" (as in Ontario and New Zealand). In fact, the cases were based on a random sample of real patients who had undergone bypass surgery in Northern Ireland in 1991.[8] Each patient was described by 10 clinical "cues." A sample case is shown in figure 1, while table 1 summarises the patients' characteristics. Each participating doctor was given a folder of details of 60 patients, of which 10 were duplicated cases, to assess.

[Figure 1 ILLUSTRATION OMITTED]

Table 1 Characteristics of the "paper patients"

Clinical characteristic                    No(%)(*)

Median (range) age (years)              57.5 (39 to 71)
Median (range) % of ideal weight       125.5 (103 to 158)

Sex:

Male                                         39 (78)
Female                                       11 (22)

Smoking status:

Non-smoker                                   36 (72)
Smoker                                       14 (28)

Expected morbidity/mortality
 related to procedure:

Average                                      40 (80)
Higher than average                          10 (20)

Exercise stress test:

High risk                                    40 (80)
Not high risk                                10 (20)

CCS angina grade:

I                                             5 (10)
II                                           17 (34)
III                                          14 (28)
IVa                                           5 (10)
IVb                                           5 (10)
IVc                                           4 (8)

Left ventricular function:

Normal                                       32 (64)
Abnormal                                     18 (36)

Left main stem stenosis:

0-49%                                        43 (86)
50-74%                                        2 (4)
[is greater than or equal to] 75%             5 (10)

Severly diseased vessels:

0                                             4 (8)
1                                            10 (20)
2                                            15 (30)
3                                            18 (36)
4                                             3 (6)

Although a few models were influenced by the demographic cues, the magnitude of this effect (reflected by the [Beta] or regression coefficient, which expresses the change m priority rating that accrues from each unit change in the clinical variables) was generally much smaller than that of the major clinical cues such as the severity of angina or left main stem stenosis (fig 3).[11]

[Figure 3 ILLUSTRATION OMITTED]

Discussion

What do we think scoring systems will achieve?

Our approach differs from that of the Ontario group. Firstly, by using data from real patients we hoped to avoid the potential for unrealistic combinations of clinical cues. Secondly, we derived decision policy models for each judge, whereas Naylor et al produced a composite regression model after averaging the ratings of their panellists.[3] The validity of such an approach has been seriously questioned.[11] Thirdly, we addressed the influence of demographic and lifestyle factors and the judges' beliefs about the probable efficacy of surgery.