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Three Part Question

In [adult patients presenting with traumatic knee pain] are the [Ottawa knee rules] reliable at [identifying patients who require radiography]?

Clinical Scenario

A 30 year old man presents to the ED with a painful knee due to a traumatic sporting injury. You suspect a soft tissue injury and wonder if he needs an x-ray?

Search Strategy

Medline 1948 - July 2011 using the Pubmed interface
Updated search using OVID Medline 1948 – June Week 4 2011
Embase 1980 – Week 26 2011
CINAHL 1937 – July 2011
Cochrane database
Medline 1948 – July 2011 using the Pubmed interface
Search terms:
(clinical[All Fields] AND decision[All Fields] AND rules[All Fields] AND ("knee"[MeSH Terms] OR "knee"[All Fields] OR "knee joint"[MeSH Terms] OR ("knee"[All Fields] AND "joint"[All Fields]) OR "knee joint"[All Fields])) AND ("humans"[MeSH Terms] AND English[lang] AND "adult"[MeSH Terms]). Found 11 results of which 9 were relevant.
(ottawa[All Fields] AND ("knee"[MeSH Terms] OR "knee"[All Fields] OR "knee joint"[MeSH Terms] OR ("knee"[All Fields] AND "joint"[All Fields]) OR "knee joint"[All Fields]) AND rule[All Fields]) AND ("humans"[MeSH Terms] AND English[lang] AND "adult"[MeSH Terms]) Found 12 results (all relevant) of which 8 were duplicates of other searches.
Updated search using OVID Medline 1948 – June Week 4 2011
Search terms:
‘clinical decision rules knee’ limited to English, humans, full text and related terms. ound 1516 results of which 2 relevant, both duplicates of previous search results.
‘ottawa knee rule’ limited to English, humans, full text, adults 19+ years and related terms. Found 218 results of which 3 relevant, 2 duplicates of previous searches.
Advanced search strategy:
1. Clinical decision rule.mp (178)
2. Clinical decision rules.mp (132)
3. Clinical prediction rule.mp (270)
4. Clinical prediction rules.mp (185)
5. Clinical decision rul$.mp (285)
6. Clinical prediction rul$.mp (426)
7. Or/1-6 (702)
8. Exp Knee/ (9233)
9. Knee.mp (86091)
10. Exp Knee Injuries/ (13496)
11. Or/8-10 (86222)
12. 7 and 11 (30)
Found 30 results of which 14 relevant, 10 found in previous searches.
Embase 1980 – Week 26 2011
Search terms:
‘Ottawa knee rule’ limited to related terms, humans, English, full text and adult <18 to 64 years> Found 423 results of which 5 relevant, 3 being duplicates of previous searches.
‘Pittsburgh knee rule’ limited to related terms, humans, English, full text and adult <18 to 64 years> Found 1260 results of which 4 relevant, 2 duplicates of previous searches.
CINAHL 1937 – July 2011
Search terms:
‘clinical decision rules’(title) AND ‘knee’(title) Found 4 results of which 2 were relevant, 1 being a duplicate of previous searches.
‘ottawa knee rule’(title) Found 13 results of which 6 relevant, 2 being duplicates of previous searches.
Cochrane database
‘clinical decision rule knee’ Found 5 results of which 3 relevant, 2 being duplicates of previous searches.
‘ottawa knee rule’ Found 0 results.

Search Outcome

A total of 6 papers were of sufficient quality to be included for critical appraisal.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Bachmann L.M., Haberzeth S. et al 2004 USA	Systematic review of 11 papers on validation of the Ottawa rule. 5 excluded. Total of 6 papers included involving 4249 patients analysed.	Systematic review	Mean sensitivity	98.5%	No testing for heterogeneity.
			Mean specificity	49.0%
			Mean negative likelihood ratio	0.05
			Probability of fracture after negative rule result	0.37% (assuming 7% fracture prevalence rate)
Stiell I.G., Wells G.A. et al 1997 Canada	Convenience sample totalling 3907 patients presenting to 4 hospitals. Two hospitals assigned controls and two implemented intervention (use of Ottawa rule) after 12 months. Most underwent radiology to determine sensitivity and specificity of rule, others followed up to check for missed fractures. Level of inter-observer agreement calculated.	Cohort	Sensitivity	1.0	No power calculation stated. Rule could only be interpreted for 987 patients as documents incomplete. Inter-observer agreement carried out on only 69 cases. One of intervention hospitals involved in creation and validation of rule previously, so staff may be more experienced using it. Interpretation of x-rays by radiologists not blinded.
			Specificity	0.48
			Negative predictive value	1.0
			Positive predictive value	0.11
			Inter-observer agreement	K=0.91
			Reduction in radiography: Intervention group	26.4%
			Control group	1.3%
Emparanza J.I., Aginaga J.R. 2001 Spain	1522 patients assessed in 11 hospitals. All underwent radiology to determine sensitivity and specificity of rule.	Cohort	Sensitivity	1.0	Inter-observer agreement for interpretation of criteria not assessed. X-rays interpreted by physicians – no blinding. Participating physicians internists / family physicians who have unofficial training in Emergency Medicine.
			Specificity	0.52
			Negative predictive value	1.0
			Positive predictive value	0.11
			Potential reduction in radiography	49%
Atkinson P., Boyle A. et al 2004 UK	58 patients assessed by junior doctors with criteria completed after examination. Further 72 patients assessed for positive signs outlined in clinical decision rule after formal teaching. Most underwent radiography to assess sensitivity and specificity of rule. All followed up to check for missed fracture.	Cohort	Before rule knowledge: Sensitivity	80%	Small sample size. Low initial rate and small reduction in radiography rates. Only included junior doctors.
			Specificity	43.4%
			Negative predictive value	95.8%
			Positive predictive value	11.8%
			No. of missed fractures	1 of 5
			After rule introduction: Sensitivity	100%
			Specificity	53.8%
			Negative predictive value	100%
			Positive predictive value	18.9%
			No. of missed fractures	0 of 7
			Reduction in radiography	3%
Tigges S., Pitts S. et al 1999 USA	Convenience sample of 378 patients assessed for rule criteria and radiology findings.	Cohort	Sensitivity	0.98	Selection and work-up bias for patient inclusion. Poor follow-up to assess for missed fractures.
			Specificity	0.19
			Positive predictive value	0.13
			Negative predictive value	0.98
			Positive likelihood ratio	1.21
			Negative likelihood ratio	0.12
Jalili M., Gharebaghi H. 2010 Iran	Convenience sample of 283 patients assessed for rule criteria. All received radiography to calculate sensitivity and specificity rates of rule.	Cohort	Sensitivity	95.4%	Inter-observer compliance not assessed. X-rays assessed by orthopaedic surgeon and all fractures considered significant (even if not clinically significant).
			Specificity	44.0%
			Negative predictive value	99.1%
			Positive predictive value	12.5%
			Negative likelihood ratio	0.09%
			No. of missed fractures	1 of 22
			Reduction in radiography	41%

Comment(s)

The Ottawa rule has been widely validated and its generalisability confirmed. It is a very reliable tool for accurately assessing whether a patient requires radiography and can be used by different levels of medically-trained staff effectively.

Clinical Bottom Line

The Ottawa knee rule is an excellent clinical decision tool and should be used by triage nurses and physicians in emergency departments alongside clinical judgement and experience to ensure a high level of specificity and sensitivity is maintained.

References

1. Bachmann L.M., Haberzeth S., Steurer J., ter Riet G. The accuracy of the Ottawa knee rule to rule out knee fractures Annals of Internal Medicine 2004; 121 - 124
2. Stiell I.G., Wells G.A., Hoag R.H., Sivilotti M.L. et al Implementation of the Ottawa knee rule for the use of radiography in acute knee injuries Journal of the American Medical Association 1997; 2075 - 2079
3. Emparanza J.I. and Aginaga J.R. Validation of the Ottawa knee rules Annals of Emergency Medicine 2001; 364 - 368
4. Atkinson P., Boyle A., Chisholm E. X-ray requesting patterns before and after introduction of the Ottawa knee rules in a UK emergency department European Journal of Emergency Medicine 2004; 204 - 207
5. Tigges S., Pitts S., Mukundan Jr S., Morrison D., Olson M., Shahriara A. External validation of the Ottawa knee rules in an urban trauma center in the United States American Journal of Roentgenology 1999; 1069 - 1071
6. Jalili M. and Gharebaghi H. Validation of the Ottawa knee rule in Iran: a prospective study Journal of Emergency Medicine 2010; 849 - 851