The Wells rule does not adequately rule out deep venous thrombosis in primary care patients.
BACKGROUND
Using data from secondary care outpatients, Wells and colleagues developed a diagnostic rule to estimate the probability of the presence of deep venous thrombosis (DVT). The accuracy of the Wells rule has not been properly validated for use in primary care patients in whom DVT is suspected.


OBJECTIVE
To validate the diagnostic accuracy of the Wells rule, with and without D-dimer testing, in a primary care setting.


METHODS
Cross-sectional study with prospective data collection from 1 January 2002 to 1 March 2003.


METHODS
110 primary care practices in a circumscribed geographic region in The Netherlands.


METHODS
1295 consecutive patients who consulted their primary care physician about symptoms suggestive of DVT.


METHODS
All patients underwent history-taking and physical examination to calculate the Wells rule score, and D-dimer testing. Repeated leg ultrasonography was the reference standard to determine the true presence or absence of DVT.


RESULTS
In the primary care setting, 12.0% of patients in the low-risk group had DVT; the original study by Wells and colleagues reported a rate of 3% among such patients. When combined with negative results on a D-dimer test, the Wells rule yielded a prevalence of DVT of 2.9% in the lowest-risk group, whereas the prevalence was 0.9% in the original study.


CONCLUSIONS
Patients with previous DVT were included, and the diagnostic reference standard was different from that used in Wells and colleagues' original study.


CONCLUSIONS
The Wells rule, alone or in combination with D-dimer testing, does not guarantee accurate estimation of risk in primary care patients in whom DVT is suspected.
Oudega
Ruud
R
The Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands. r.oudega@knmg.nl
Hoes
Arno W
AW
Moons
Karel G M
KG
D000328:Adult; D000368:Aged; D003430:Cross-Sectional Studies; D005260:Female; D005338:Fibrin Fibrinogen Degradation Products / Q000032:analysis; D006403:Hematologic Tests; D006801:Humans; D008297:Male; D008487:Medical History Taking; D008875:Middle Aged; D009426:Netherlands; D010808:Physical Examination; D011237:Predictive Value of Tests; D011320:Primary Health Care; D011446:Prospective Studies; D012307:Risk Factors; D018616:Ultrasonography, Doppler, Duplex; D020246:Venous Thrombosis / Q000097:blood / Q000175:diagnosis* / Q000000981:diagnostic imaging
D005338:Fibrin Fibrinogen Degradation Products