Journal Reading Topic: Ottawa Ankle Rules

1
Journal ReadingTopic Ottawa Ankle Rules

• ??? ??? ??
• ??? ??? ??

2
Ottawa Ankle Rules

• The OAR in Adults in the ED
• The OAR in Pediatrics in the ED
• The OAR in Asia

3
Ottawa Ankle Rules (original)

• 1st rule (for ankle radiographic series)
• Pain near the malleoli
• Age 55 years or greater
• Inability to bear weight immediately after the
  injury and for 4 steps in the emergency
  department.
• Bone tenderness at the posterior edge or tip of
  either malleolus.

Stiell et, Ann Emerg Med, 1992
4
Ottawa Ankle Rules (original)

• 2nd rule (for foot radiographic series)
• Pain in the midfoot
• Bone tenderness at the navicular bone, the
  cuboid, or the base of the 5th metatarsal

Stiell et, Ann Emerg Med, 1992
5
Ottawa Ankle Rules (refined)

• 1st rule (for ankle radiographic series)
• Bone tenderness at the posterior edge or tip of
  the lateral malleolus
• Bone tenderness at the posterior edge or tip of
  the medical malleolus
• Inability to bear weight both immediately after
  the injury and for 4 steps in the emergency
  department

Stiell et, JAMA, 1993
6
Ottawa Ankle Rules (refined)
7
Ottawa Ankle Rules (refined)

• 2nd rule (for foot radiographic series)
• Bone tenderness at the base of the fifth
  metatarsal bone
• Bone tenderness at the navicular bone
• Inability to bear weight immediately after the
  injury and for 4 steps in the emergency department

Stiell et, JAMA, 1993
8
Ottawa Ankle Rules (refined)
9
A Pooled Analysis of the Ottawa Ankle Rules Used
on Adults in the ED

• RONALD J. MARKERT, PHD, MARY E. WALLEY, MD, TODD
  G, GUTTMAN, MD, JD, TAHUL MEHTA, MD

Am J Emerg Med 199816564-567
10
Background

• Ottawa ankle rules bring an practical and
  cost-effective approach to decision-making in the
  ED for the evaluation of ankle and foot injuries.
• Individual studies of the rules generally showed
  that routine x-ray for acute ankle and midfoot
  injuries in the ED was unnecessary and
  inappropriate.

11
Background

• In this report, the authors pooled the data from
  7 studies (in 3 different countries with
  different medical-social structures and 5
  different EDs) to provide more precise and stable
  estimates of the diagnostic effectiveness of the
  Ottawa ankle rules.

12
Methods

• Study design
• All relevant studies published through April 1996
  were identified by computerized and manual
  literature searches.
• Studies were judged acceptable
• Populations from which study samples were drawn
  (ie, ED adult patients presenting with acute
  blunt ankle or midfoot injuries)
• Application of the original and/or refined
  criteria used in the Ottawa ankle rules
• Use of the same gold standard for determining the
  diagnosis (ie, ankle and foot radiographic series)

13
Methods

• Clinical diagnostic test criteria
• Original Ottawa ankle rules
• Refined Ottawa ankle rules

14
Methods

• Data analysis
• Sensitivity, specificity, positive and negative
  predictive values for each studies.
• Sensitivity, specificity, and positive and
  negative predictive values with 95 confidence
  intervals for the combined results.

15
Results
16
Results
17
Results
18
Results
19
Results

• The original and refined rules produced similar
  results for both ankle and foot injuries.
• The combined results for either original or
  refined rules showed high sensitivity and
  negative predictive value for both foot and ankle
  (few false negatives) - best used to rule out the
  diagnosis of an fractured value or foot
• Duo to low specificity and positive predictive
  value, the rules are not appropriate to rule in
  an ankle or foot fracture.

20
Discussion

• Radiography is recommended only for the adult ED
  patient with an acute ankle or foot injury who
  test positively on the Ottawa ankle rules.

21
Discussion

• For patient/physician interactions
• Using the Ottawa ankle rules shifts the emphasis
  from examination of a radiograph to examination
  of the patients.
• Many clinicians wont be hesitant to not order
  the x-ray for ankle injuries, duo to the rules
  provides firm ground for determining when to
  obtain ankle radiographs.

22
Discussion

• Patient Demand Factor prevented by well
  explanation.
• Medical Liability Risks appropriately
  designed and statistically validated guideline
  (Ottawa ankle rules) support clinicians.

23
Discussion

• Cost-effective medical care
• 8 Canadian hospitals a 21.9 absolute reduction
  in ankle radiographs (82.8 v 60.9).
• Similar results in foot injuries.
• Rate of missed fractures and patient
  dissatisfaction did not increase.

24
Discussion

• Ottawa rules in pediatrics
• Chande et, 68 patients with acute ankle injury a
  pediatric ED
• Similar results as in adult studies (sensitivity
  100, specificity 32, positive predictive
  value 28, negative predictive value 100)

25
Conclusion

• The Ottawa ankle rules are an effective clinical
  practice guideline for acute ankle and foot
  injuries in the adult ED patients.
• Patients with negative finding based on the rules
  are highly unlikely to have a fractured ankle or
  foot.
• The diagnosis for positive patients is much less
  certain, suggesting the need for radiography.

26
The Ottawa Ankle Rules in Asia Validating a
Clinical Decision Rule for Requesting X-rays in
Twisting Ankle and Foot Injuries

• J Emerg Med, Vol. 17, No. 6, pp. 945-947, 1999

27
Introduction

• The Ottawa Ankle Rules have met with varying
  levels of success in validation around the world,
  but has not been done for an Asian population.
• The authors of this paper wanted to find out if
  the OAR are applicable to Asian patient
  population.
• The potential benefit would be a decrease in the
  number of x-ray studies requested, shorter
  turnaround times, less radiation for patients,
  and cost reduction for the hospital.

28
Materials and Methods

• Refined Ottawa Ankle Rules
• Inclusion criteria
• Age 12 years or more (differed from the original
  paper excluded patients under 18 y/o)
• Injury sustained within 7 days of fewer
• Exclusion criteria
• Pregnancy, altered mental state at the time of
  consultation, patients who had been referred with
  an x-ray study, revisits, multiple trauma,
  patients with isolated skin injuries.

29
Materials and Methods

• The radiologists were not blinded to the clinical
  findings.
• A clinical significant fracture was an avulsed
  fracture fragment greater then 3 mm on the x-ray.

30
Results

• 494 patients enrolled in the study.

31
Results
32
Discussion

• Many of patients were unable to recall whether
  they were able to bear weight immediately after
  injury (most of they count not bear weight in the
  ED)
• The OAR should be modified to include patients
  who were unable to bear weight either at the time
  of injury or at the time on consultation (improve
  sensitivity from 0.9 to 0.99, at the cost of
  requesting about 3 more x-ray studies).

33
Conclusion

• The OAR cannot be used to screen for the need for
  x-ray studies in Asian patients duo to its high
  false-negative rate.
• After modification to include inability to weight
  bear at the time of injury or in the ED, the
  sensitivity of the rules improved to a acceptable
  level (99 sensitivity), at the cost of
  requesting about 3 more x-ray studies.

34
Validation of the Ottawa Ankle Rules in a Hong
Kong ED

• Am J Emerg Med 200119429-432

35
Methods

• Refined Ottawa Ankle Rules
• Inclusion criteria
• Age 16 years or older
• Injury sustained within 7 days or less
• Exclusion criteria (same as the previous paper)

36
Methods

• The radiologists were blinded to the results of
  the OAR and the emergency physicians
  interpretation.
• A clinical significant fracture was an avulsed
  fracture fragment greater then 3 mm on the x-ray.

37
Results

• 798 patients (25 patients refused)
• Men/women 437/336
• Age 16 to 93 years (mean 37 years)

38
Results

• 144 fractures (18.6)

39
Results

• 1 Significant fr. and 2 insignificant fr. were
  not identified.

40
Discussion

• Sensitivity of the OAR in this series was 97.7,
  and the potential radiograph cost saving was
  32.5.
• Several studies failed to reproduce the high
  sensitivity of the OAR
• Methodological problems, Error of study design,
  or Not use real OAR.
• The radiologists were blinded to the clinical
  findings avoiding the bias and achieving an
  accurate estimation of the sensitivity of the OAR.

41
Conclusion

• The OAR is an accurate clinical decision rule for
  guiding decisions for ordering radiographs for
  Chinese patients with foot and ankle injuries.
• The application of the OAR has the potential
  advantages of reducing unnecessary radiation
  exposure and health costs.