We are currently updating our website, and will have our new version online soon. Please check back later this fall.

Mailing List

Subscribe to the KT Canada mailing list




Once you have signed up, you will receive a confirmation email with your username and password. To activate your account, follow the instructions in the email.


Centre for Evidence-
Based Medicine

Completed Systematic Reviews Worksheet for Evidence-Based Geriatric Medicine


Stroke unit trialists' collaboration. Collaborative systematic review of the randomised trials of organised inpatient (stroke unit) care after stroke. BMJ 1997;314:1151-9.

Are the results of this systematic review (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?
  3. Does it include a methods section that describes assessing their individual validity?
    No, but does include characteristics of individual trials
  4. Were the results consistent from study to study?
    Consistent results when death is the outcome. When death or dependency is the outcome, some heterogeneity but this was explored and seems to reflect the nature of the control group i.e. less heterogeneity when the stroke unit group was compared to a general medical unit. There was significant heterogeneity in length of stay.

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) 0.05 209 139 104 83 69 59 52 46 41
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
0.50 38 25 18 14 11 9 8 7 6
0.70 44 28 20 16 13 10 9 7 6
0.90 101 64 46 34 27 22 18 15 12

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?

How great would the potential benefit of therapy actually be for your individual patient?

  1. 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):
    EER and CER provided in Best Evidence. For death and dependency the NNT is 15 (12 to 41)
  2. 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?
    Needs to be assessed in each patient
  2. Are they met by this regimen and its consequences?
    Needs to be assessed in each patient

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


Continue to CAT