### Prognosis Scenario

Anita Gross, Ted Haines, Diane Hartley.
Contact Details: Bert Chesworth, Mary Ann O’Brien

You are a newly graduated physiotherapist working in an out-patient clinic. Your client, a 22 year old male university student, had an open surgical repair of his torn left anterior cruciate ligament 8 weeks ago. In your discussion of treatment goals, he tells you he hopes to be able to return to intramural basketball. You decide that you need more information so you plan to search MEDLINE on-line at the end of the day. Prior to searching, you form the following question: “In people who have had an open surgical repair to the anterior cruciate ligament, what are the chances of returning to strenuous sport?”

Search Terms
Knee injuries (MeSH), anterior cruciate ligament repair (text word) combined with randomized controlled trials (MeSH), random allocation (MeSH) searched from 1988-1998

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.

• Is the evidence about prognosis valid?
• Is this valid evidence about prognosis important?
• Can you apply this valid and important evidence about prognosis in caring for your client?

### 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?

Was a defined, representative sample of patients assembled at a common (usually early) point in the course of their disease?
Yes.
Was patient follow-up sufficiently long and complete?
Yes up to 52 months.
Were objective outcome criteria applied in a “blind” fashion?
No.
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.
Was there validation in an independent group (“test-set”) of patients?
No.

#### Are the valid results of this prognosis study important?

How likely are the outcomes over time?
13/23 (57%) at a mean follow-up time of 52 months.
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
$$sqrt{frac{ptimes(1-p)}{n}} \\ text{where p is proportion and \\n is number of patients}$$
$$text{If p = 13/23 = 0.57 (or 57%) and n=23}$$
$$sqrt{frac{0.57times(1-0.57)}{23}} \\ = 0.103 \\ text{95% CI is 57% ± 1.96 x 10.3% or 36.8% to 77%}$$

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

Were the study patients similar to your own?
Not Clear.
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.

### Open ACL repair: Chance of returning to sport after surgery

#### Clinical Bottom Line

57% (95% CI 37 to 77%) chance of returning to sport 4 years after surgical repair of an isolated tear of the anterior cruciate.

#### 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.

#### Clinical Question

In people who have had an open surgical repair to the anterior cruciate ligament, what are the chances of returning to strenuous sport?

#### Search Terms

Knee injuries (MeSH), anterior cruciate ligament repair (text word) combined with randomised controlled trials (MeSH), random allocation (MeSH) searched from 1988-1998.

#### The Study

107 patients with acute knee injury examined by arthroscopy under anaesthesia. There were four groups: Group A included 24 patients with an isolated ACL tear that was repaired and augmented surgically. Group B included 31 patients with an isolated ACL tear that was not repaired. Group C included 24 patients who had an ACL tear combined with an MCL tear and both were repaired. Group D consisted of 28 patients with both ACL and MCL tears where only the MCL was repaired.

#### The Evidence

• Well-defined sample at uniform (early) stage of illness..?, yes;
• Follow-up long enough..?, yes;
• Follow-up complete..?, yes;
• Blind and objective outcome criteria..?, no;
• Adjustment for other prognostic factors..?, no;
• Validation in an independent “test*set” of patients..?, no;
##### The Evidence (for Group A)
Prognostic Factor Outcome Time Measure Confidence Interval

If the pre-test probability is intermediate (e.g. 50%) then a positive clinical test would be helpful, yielding a post-test probability of 81%.

If the pre-test probability is low (e.g. 20 %) then the clinical test is not useful (post-test probability = 52%).