Optimisation of the diagnostic strategy for suspected deep-vein thrombosis in primary care.
Recently, a diagnostic score was developed to safely exclude deep-vein thrombosis (DVT) in primary care. A large prospective study, in which general practitioners used this diagnostic score to decide which patients needed referral, revealed that the number of referrals for ultrasound measurements was reduced by almost 50%, at the cost of an acceptably low risk (1.4%, 95% confidence interval [CI] 0.6% to 2.9%) of venous thromboembolic events in non-referred patients. However, simple adjustments to the diagnostic score (so-called updating) might further improve the accuracy; i.e. reduce the proportion of missed diagnoses (safety) or increase the proportion of patients who do not need to be referred (efficiency). We applied two updating methods to determine whether adjusting the weights of the predictors or adding new predictors could further improve the accuracy of the diagnostic score. The weights of the predictors did not need to be adjusted, but inclusion of 'history of DVT' and 'prolonged travelling' significantly added predictive value (p-values 0.014 and 0.023, respectively). However, adding these predictors to the diagnostic score did not improve the safety and efficiency: at equal safety (1.4% missed diagnoses among the non-referred patients), the efficiency was lower (43.5%, 95% CI 40.4% to 46.6% compared to 49.4%, 95% CI 46.3% to 52.5%). The diagnostic score for excluding DVT in primary care has good accuracy in its original form and could not be improved by including additional predictors. This suggests that the original diagnostic score can be used to safely exclude clinically suspected DVT in primary care.
Janssen
Kristel J M
KJ
Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands. K.J.M.Janssen@umcutrecht.nl
van der Velde
Eit F
EF
Ten Cate
Arina J
AJ
Prins
Martin H
MH
van Weert
Henk C P M
HC
Stoffers
H E Jelle H
HE
Büller
Harry R
HR
Oudega
Ruud
R
Hoes
Arno W
AW
Toll
Diane B
DB
Moons
Karel G M
KG
D003661:Decision Support Techniques; D003936:Diagnosis, Computer-Assisted / Q000379:methods* / Q000592:standards; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D008487:Medical History Taking; D008875:Middle Aged; D011320:Primary Health Care / Q000379:methods; D018570:Risk Assessment; D014195:Travel; D014463:Ultrasonography; D020246:Venous Thrombosis / Q000175:diagnosis* / Q000000981:diagnostic imaging