Recommendations

Internal Medicine Society of Australia and New Zealand

Recommendations from the Internal Medicine Society of Australia and New Zealand on avoiding medication-related harm, monitoring antibiotic treatment, fainting and CT pulmonary angiography. IMSANZ represents over 700 Consultant Physicians and trainees in Internal Medicine (also known as General Medicine or General and Acute Care Medicine) within Australia and New Zealand. The Society provides a mechanism for developing the academic and professional profile of general medicine and seeks to advocate for, and sponsor the educational training, research and workforce requirements of general internal medicine.

5.

Don’t request computerised tomography pulmonary angiography (CTPA) as first-choice investigation in non-pregnant adult patients with low risk of pulmonary thromboembolism (PTE) by Wells’ score (score <= 4); imaging can be avoided in low risk patients if D-dimer test is negative after adjusting for age

The D-dimer test is highly sensitive for deep vein thrombosis and pulmonary thromboembolism, such that a negative result in non-pregnant adults (adjusted for age) rules out this condition in patients with low pre-test probability. A positive result is however non-specific and may be due to many other conditions apart from PTE. In ruling out PTE, D-dimer assay should be the first choice investigation in patients classified as being low risk according to the Wells’ score (equal to or less than 4).

These considerations are heightened by the risks associated with CTPA testing such as radiation exposure and incidental imaging findings, e.g. lung nodules and adrenal lesions that may provoke further investigations and diagnosis of isolated small subsegmental emboli whose natural history is unknown and for which anticoagulation is not yet shown to be of benefit. There is, however, a 1 – 3% failure rate with a low risk Wells’ score and negative D-dimer prediction method, so close follow-up is indicated in all patients in whom a D-dimer has been requested. Note that laboratories do not report age adjusted values, though it is well known that D-dimer levels rise with age in the presence of co-morbidities.

An example of age adjustment, endorsed by the clinical guidelines committee of the American College of Physicians (see reference from Raja et al below) quotes a upper limit of normal for D-dimer tests equal to age × 10 ug/L, rather than a generic upper limit of of 500 ug/L. Clinical judgement is necessary in applying this adjustment method, with some reports adopting a more conservative formulae of age x 5 ug/L.

The Well's score is computed as follows:
Variable Points
Clinical signs and symptoms of deep venous thrombosis 3
Alternative diagnosis less likely 3
Heart rate >100/min 1.5
Immobilisation 1.5
Previous pulmonary embolism or deep venous thrombosis 1.5
Haemoptysis 1.0
Malignancy (receiving treatment, treated within last 6 months or palliative) 1.0

Modified Wells score (mWS) of ≤4 = low risk patients, >4 = high risk patients

Reference: Wells PS, Anderson DR, Rodger M, Ginsberg JS, Kearon C, Gent M, et al. Derivation of a simple clinical model to categorize patients probability of pulmonary embolism: increasing the models utility with the SimpliRED D-dimer. Thromb Haemost. 2000:83 (3): 416–20.

Note: D-dimer is routinely elevated from the first trimester and gestational age normative D-dimer levels have not been sufficiently validated to allow their use as a risk stratification tool in pregnancy. Most pregnant women with no clinical evidence of DVT will have negative lower limb venous Doppler as pulmonary emboli originate in the pelvic veins, which are not accurately evaluated with duplex compression Doppler ultrasound. In such cases, ventilation perfusion lung scanning is the test of choice, due to lower breast dose than CTPA in pregnant women with suspected pulmonary embolism provided chest radiograph is normal and an alternative diagnosis such as neoplasia or aortic dissection, that are detectable with CT and not with VQ, is not suspected.

Supporting evidence

  • Carrier M, Righini M, Wells PS, et al. Subsegmental pulmonary embolism diagnosed by computed tomography: incidence and clinical implications. A systematic review and meta-analysis of the management outcome studies. J Thromb Haemost 2010; 8:1716-22.
  • Ong CW, Malipatil V, Lavercombe M, et al. Implementation of a clinical prediction tool for pulmonary embolism diagnosis in a tertiary teaching hospital reduces the number of computed tomography pulmonary angiograms performed. Intern Med J 2013; 43(2):169-74.
  • Pasha SM, Klok FA, Snoep JD, et al. Safety of excluding acute pulmonary embolism based on an unlikely clinical probability by the Wells rule and normal D-dimer concentration: A meta-analysis. Thromb Res 2010; 125:e123-7.
  • van Es N, van der Hulle T, van Es J, et al. Wells rule and D-dimer testing to rule out pulmonary embolism. A systematic review and individual-patient data meta-analysis. Ann Intern Med 2016; 165:253-61.
  • Raja AS, Greenberg JO, Qaseem A, et al. Evaluation of patients with suspected acute pulmonary embolism: best practice advice from the clinical guidelines committee of the American College of Physicians. Ann Intern Med 2015; 163:701–11.

How this list was made How this list was made

A panel of IMSANZ members produced an initial list of 32 low value tests, treatments and management decisions frequently encountered in general medicine services. This initial list was distributed via e-mail to 350 members of a working group comprising approximately 50 general physicians as well as nurses and allied health professionals who ranked the items in terms of priority and were free to nominate additional items. Based on their responses, the list was condensed to 15 items including three which were not previously listed. These 15 items were the subject of a face-to-face forum of the working group which reached consensus on a final list of 10.

Recommendations on ‘what not to do’ were formulated around these 10 items and a summary of the evidence for each recommendation was prepared. An online survey based on this work was presented to, and approved by, IMSANZ Council. The survey was sent to all IMSANZ members asking respondents to assign a score from 1 to 5 for each recommendation on three criteria: ‘The clinical practice being targeted by this recommendation is still being undertaken in significant numbers’; ‘This recommendation is evidence-based’; and ‘This recommendation is important in terms of reducing harm to patients and/or costs to the healthcare system’. The survey attracted 182 respondents from all across Australia and New Zealand, which was a response rate of 26%. The final top five chosen were the recommendations with the five highest average total scores assigned to them.


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