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Centre for Evidence-
Based Medicine

Completed Therapy Applicability Worksheet for EBM in Developing Countries

Citation

ISIS-2 (Second International Study of Infarct Survival) Collaborative Group. Randomised trial of intravenous streptokinase, oral aspirin, both, or neither among 17187 cases of suspected acute myocardial infarction: ISIS-2. Lancet 1988; ii:349-360.

Deciding on the Applicability of Clinical Trial Results

Biologic

  1. Are there pathophysiologic differences in the illness under study that may lead to a diminshed treatment response?
    NO. Local studies indicate similar pathologic changes, risk factors and disease pathogenesis between North Americans and Filipinos.
  2. Are there patient differences that may diminish treatment response?
    NO. Although there are no local pharmacokinetic studies, post-marketing surveys show that the incidence of major bleeding is similar. This suggests that Filipinos are no different from North Americans in terms of treatment response.

Social and Economic

  1. Are there important differences in patient compliance that may diminish the treatment response?
    NO. Since streptokinase is given intravenously in a single dose for in-hospital patients with MI, compliance is not an expected problem.
  2. Are there important differences in provider compliance that may diminish the treatment response?
    YES. Lack of an efficient blood banking system may hinder our ability to cope with episodes of major bleeding.

Epidemiologic

  1. Do my patients have comorbid conditions that significantly alter the potential benefits and risks of the treatment?
    YES. Since death from sepsis is a relatively common cause of death in our hospital accounting for 10.4% mortality. The impact of streptokinase on overall mortality may be less than expected. A better measure may be cardiac death.
  2. Are there important differences in untreated patients' risk of adverse outcomes that might alter the efficiency of treatment?
    YES. The cardiac death rate in ISIP is 10%. See computation below.

Using the local, unpublished cohort study entitled, Acute Myocardial Infarction in Tertiary Centers in Metro Manila (ISIP Study), you estimate the treatment benefit among Filipinos with acute myocardial infarction from streptokinase.

  • Overall baseline risk for in-hospital cardiac mortality among Filipinos: 10%
    (crude cardiac mortality derived from ISIP)
  • The relative risk reduction from vascular deaths in ISIS-2: 23%
    The relative risk from vascular deaths is: 77%

From the above data, you derived the absolute risk reduction and NNT for the local cohort.

EER = RR x CER
= 0.77 x 10%
= 7.7%

ARR = 10% - 7.7%
= 2.3%

NNT = 1/0.023
= 43

For presentation purposes you developed a CAT on therapy. This one-pager, easy reference will be able to present all major points and help guide you through your discussion.

Continue to CAT