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Citation:
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Are the results of this single preventive or therapeutic trial valid?
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Was the assignment of patients to treatments randomised? Was the randomisation list concealed? |
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Was follow-up of patients sufficiently long and complete? |
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Were all patients analysed in the groups to which they were randomised? |
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Were patients and clinicians kept “blind” to treatment? |
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Were the groups treated equally, apart from the experimental treatment? |
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Were the groups similar at the start of the trial? |
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Are the valid results of this randomized trial important?
SAMPLE CALCULATIONS
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Occurrence of diabetic neuropathy at 5 years among insulin-dependent diabetics in the DCCT trial |
Relative risk reduction (RRR) |
Absolute risk reduction (ARR) |
Number needed to treat (NNT) |
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Usual insulin regimen control event rate (CER) |
Intensive insulin regimen experimental event rate (EER) |
CER – EER CER |
CER-EER |
1/ARR |
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9.6% |
2.8% |
9.6% - 2.8% 9.6% = 71% |
9.6% - 2.8% = 6.8% |
1/6.8% = 15 patients |
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95% CI *Þ |
4.4% to 9.2% |
11 to 23 |
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* 95% confidence interval (CI) on an NNT = 1/(limits on the CI of its ARR) =
YOUR CALCULATIONS
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Relative risk reduction (RRR) |
Absolute risk reduction (ARR) |
Number needed to treat (NNT) |
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CER |
EER |
CER – EER CER |
CER-EER |
1/ARR |
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95% CI Þ |
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Can you apply this valid, important evidence about therapy in caring for your patient?
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Do these results apply to your patient? |
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Is your patient so different from those in the study that its results cannot apply? |
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Is the treatment feasible in your setting? |
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What are your patient’s potential benefits and harms from the therapy? |
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Method I: f |
Risk of the outcome in your patient, relative to patients in the trial. Expressed as a decimal: ______ NNT/f = ______ / ______ = ______ (NNT for patients like yours) |
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Method II: 1/(PEER x RRR) |
Your patient’s expected event rate if they received the control treatment (PEER) = ______ 1/(PEERxRRR) = 1/________ = ______ (NNT for patients like yours) |
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Are your patient’s values and preferences satisfied by the regimen and its consequences? |
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Do your patient and you have a clear assessment of their values and preferences? |
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Are they met by this regimen and its consequences? |
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