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Point-Of-Care Ultrasound Screening for Proximal Lower Extremity Deep Venous Thrombosis
Published on: February 10, 2023
Diagnostic classification in patients with suspected deep venous thrombosis: physicians' judgement or a decision
Geert-Jan Geersing1, Kristel J Janssen, Ruud Oudega
1Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands. g.j.geersing@umcutrecht.nl
Insights
Clinical decision rules for deep venous thrombosis (DVT) safely identify patients needing ultrasonography. Using these rules reduces referrals compared to general practitioner (GP) judgment, while maintaining diagnostic accuracy for DVT.
Area of Science:
- Medical diagnostics
- Clinical decision-making
- Vascular medicine
Background:
- Clinical decision rules (CDRs) assist in ultrasonography referrals for suspected deep venous thrombosis (DVT).
- Physician reliance on personal judgment over established rules can impact diagnostic pathways.
Purpose of the Study:
- To compare the diagnostic performance of a CDR against general practitioners' (GPs) probability estimates for DVT.
- To evaluate the impact of CDR use on referral rates for ultrasonography.
Main Methods:
- A cross-sectional survey involving 300 GPs in the Netherlands.
- GPs estimated DVT probability and applied a CDR to 1028 patients with suspected DVT.
- Discrimination (c-statistic) and classification were analyzed, with GP thresholds set at 10% and 20%.
Main Results:
- Analysis included 1002 patients; 14% had confirmed DVT.
- Both the CDR and GP estimates demonstrated strong discriminative power (c-statistics 0.80 and 0.82).
- CDR use led to significantly fewer referrals (51%) compared to GP estimates (79% or 65%).
- Both methods had a low missed DVT rate (1.4-2.0%).
Conclusions:
- Both GP estimates and CDRs can safely differentiate DVT presence in suspected cases.
- Implementing CDRs in primary care can optimize ultrasonography referral decisions, reducing patient numbers without compromising safety.
Background:
Clinical decision rules can aid in referral decisions for ultrasonography in patients suspected of having deep venous thrombosis (DVT), but physicians are not always convinced of their usefulness and rely on their own judgement.
Aim:
To compare the performance of a clinical decision rule with the probability of DVT presence as estimated by GPs.
Design Of Study:
Cross-sectional survey.
Setting:
Primary care practices in The Netherlands.
Method:
GPs (n = 300) estimated the probability of the presence of DVT (range 0-100%) and calculated the score for the clinical decision rule in 1028 consecutive patients with suspected DVT. The clinical decision rule uses a threshold of three points and so, for the GP estimates, thresholds were introduced at 10% and 20%. If scores were below these estimates, it was not considered necessary to refer patients for further examination. Differences between the clinical decision rule and the GP estimates were calculated; this is discrimination (c-statistic) and classification of patients.
Results:
Data of 1002 patients were eligible for analysis. DVT was observed in 136 (14%) patients. Both the clinical decision rule and GP estimates had good discriminative power (c-statistic of 0.80 and 0.82 respectively). Fewer patients were referred when using the clinical decision rule compared with a referral decision based on GP estimates: 51% versus 79% and 65% (thresholds at 10% and 20% respectively). Both strategies missed a similar and low proportion of patients who did have DVT (range 1.4-2.0%).
Conclusion:
In patients suspected of DVT both GP estimates and a clinical decision rule can safely discriminate in patients with and without DVT. However, fewer patients are referred for ultrasonography when GPs rely on a clinical decision rule to guide their decision making.
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