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Centre for Evidence-
Based Medicine

Completed Systematic Reviews Worksheet for Evidence-Based General Practice


Green S, Buchbinder R, Glazier R, Forbes A. Interventions for shoulder pain (Cochrane Review). In: The Cochrane Library, Issue 1, 1999. Oxford: Update Software.

Are the results of this systematic review of therapy valid?

  1. Is it a systematic review of randomised trials of the treatment you're interested in?
  2. Does it include a methods section that describes finding and including all the relevant trials?
    Yes, an extensive computer and hand-search was used.
  3. Does it include a methods section that describes assessing their individual validity?
    Methodological quality was assessed by two reviewers blinded to study results.
  4. Were the results consistent from study to study?
    Of 28 included studies only a few had comparable populations and methods.

Are the valid results of this systematic review important?

Translating odds ratios to NNTs. The numbers in the body of the table are the NNTs for the corresponding odds ratios at that particular patient's expected event rate (PEER).
Odds Ratios
0.9 0.85 0.8 0.75 0.7 0.65 0.6 0.55 0.5
Patient's Expected Event Rate (PEER) 0.05 2091 139 104 83 69 59 52 46 412
0.10 110 73 54 43 36 31 27 24 21
0.20 61 40 30 24 20 17 14 13 11
0.30 46 30 22 18 14 12 10 9 8
0.40 40 26 19 15 12 10 9 8 7
0.503 38 25 18 14 11 9 8 7 6
0.70 44 28 20 16 13 10 9 7 6
0.90 1014 64 46 34 27 22 18 15 125
  1. The relative risk reduction (RRR) here is 10%
  2. The RRR here is 49%
  3. For any OR, NNT is lowest when PEER = .50
  4. The RRR here is 1%
  5. The RRR here is 9%

Can you apply this valid, important evidence from a systematic review in caring for your patient?

Do these results apply to your patient?

  1. Is your patient so different from those in the systematic review that its results can't help you?
  2. How great would the potential benefit of therapy actually be for your individual patient?
    The natural history is one of spontaneous remission, but in months to years.
  3. Method I: In the table on page 1, find the intersection of the closest odds ratio from the overview and the CER that is closest to your patient's expected event rate if they received the control treatment (PEER):
  4. Method II: To calculate the NNT for any OR and PEER:
    NNT = (1-(PEERx(1-OR))/((1-PEER)xPEERx(1-OR))

Are your patient's values and preferences satisfied by the regimen and its consequences?

  1. Do your patient and you have a clear assessment of their values and preferences?
    Yes. They would prefer relief but not at the cost of risky or painful treatment.
  2. Are they met by this regimen and its consequences?

Should you believe apparent qualitative differences in the efficacy of therapy in some subgroups of patients?

Only if you can say "yes" to all of the following:

  1. Do they really make biologic and clinical sense?
  2. Is the qualitative difference both clinically (beneficial for some but useless or harmful for others) and statistically significant?
  3. Was this difference hypothesised before the study began (rather than the product of dredging the data), and has it been confirmed in other, independent studies?
  4. Was this one of just a few subgroup analyses carried out in this study?

Additional Notes


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