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Centre for Evidence-
Based Medicine

Completed Prognosis Worksheet for Evidence-Based Physiotherapy Practice

Citation

Andersson C, Gillquist J. Treatment of acute isolated and combined ruptures of the anterior cruciate ligament. Am J Sports Med 1992;20:7-12.

Are the results of this prognosis study valid?

  1. Was a defined, representative sample of patients assembled at a common (usually early) point in the course of their disease?
    Yes
  2. Was patient follow-up sufficiently long and complete?
    Yes up to 52 months
  3. Were objective outcome criteria applied in a "blind" fashion?
    No
  4. If subgroups with different prognoses are identified, was there adjustment for important prognostic factors?
    Looked at patients with isolated anterior cruciate injuries as well as those with combined injuries e.g. meniscal tears
  5. Was there validation in an independent group ("test-set") of patients?
    No

Are the valid results of this prognosis study important?

  1. How likely are the outcomes over time?
    13/23 (57%) at a mean follow-up time of 52 months
  2. How precise are the prognostic estimates?
    95% confidence interval: 37% to 77%

If you want to calculate a Confidence Interval around the measure of Prognosis:

Clinical Measure Standard Error (SE) Typical calculation of CI
Proportion (as in the rate of some prognostic event, etc) where:

the number of patients = n

the proportion of these patients who experience the event = p
sqrt((px(1-p))/n)
where p is proportion and n is number of patients
If p = 13/23 = 0.57 (or 57%) and n=23
sqrt((0.57x(1-0.57))/23)
= 0.103

95% CI is 57% ± 1.96 x 10.3% or 36.8% to 77%

Can you apply this valid, important evidence about prognosis in caring for your patient?

  1. Were the study patients similar to your own?
    Not Clear
  2. Will this evidence make a clinically important impact on your conclusions about what to offer or tell your patient?
    This evidence will provide long term guidance but isn't helpful in the short term.

Additional Notes

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