A Retrospective Review of the Appropriateness of D-Dimer Ordering and Interpretation Using Wells' Clinical Probability Criteria
Bibliographic record
Abstract
Introduction The D-dimer has been validated in diagnostic venous thromboembolism (VTE) algorithms. The high sensitivity of the assay allows for safe exclusion of VTE in patients with low clinical pre-test probability and a negative D-dimer. The Wells score for Deep Vein Thrombosis (DVT) and Pulmonary Embolism (PE) are validated pre-test probability tools which help guide physicians on when to order a D-dimer in patients with suspected VTE. However, we suspect these scoring tools are often under-utilized by physicians leading to inappropriate D-dimer ordering and subsequent interventions. We sought to explore the landscape of D-dimer ordering at our institution. Methods We conducted a retrospective chart review of 482 patients in whom a D-dimer had been ordered over a 3-month period at the University of Alberta Hospital, a tertiary care teaching hospital in Edmonton, Canada. Charts were reviewed for patient demographics, specialty of ordering physician, apparent indication for ordering, patient risk factors for VTE and evidence of a pre-test probability (PTP) calculation. WIf no PTP score was documented, we retrospectively calculated Wells DVT or PE scores. VTE was deemed likely with a calculated Wells score for DVT ≧2 or Wells score for PE >4. In the case of high PTP for PE, patients should go directly to imaging and a D-dimer should not be performed. A cut off of ≥ 0.50 mg/L was deemed a positive D-dimer (STA-LIATEST). We also reviewed subsequent investigations thought to be influenced by interpretation of the D-dimer including: ventilation/perfusion (V/Q) and pulmonary angiography (CTPA) scans, and upper and lower extremity doppler ultrasound studies. We then used multivariable logistic regression analysis to evaluate the proportion of patients who received imaging despite a low PTP and negative D-dimer. Results Seventy eight percent of D-dimers were ordered by Emergency physicians while 15.3% were drawn on admitted patients, and 5.8% in the outpatient setting. The indication for ordering was unknown in 87 (17.5%) of cases. Pre-test probability scores were documented in only 8 (1.6%) of cases. All of those documented were the Wells PE score. When Wells DVT and PE scores were calculated retrospectively, 30.0% and 17.1% (87 cases) were deemed 'likely' for VTE, respectively. However, imaging was performed in 172 cases (34.6%), including in 36 cases despite a negative D-dimer result and low PTP. In contrast, 68 cases (17.2%) had a D-dimer performed with a high Wells PTP for PE despite the recommendation to proceed directly to imaging. VTE (either DVT or PE) was confirmed by imaging in 32 (18.6%) of cases, the majority (53.1%) had a high retrospective PTP. Conclusions Inappropriate ordering and interpretation of D-dimers remains a significant problem despite the implementation of clinical guidelines and pre-test probability algorithms, namely the Wells score for DVT and PE meant to guide physicians. This leads to unnecessary cost, radiation exposure, and prolonged contact with the health care system for patients. This suggests the need for quality improvement initiatives which draw physician's attention to pre-test probability tools which can curbing subsequent inappropriate investigations and improve patient care. Disclosures Wu: Servier: Other: advisory board; BMS-pfizer: Honoraria, Other: advisory board; leo pharma: Other: advisory board; Pfizer: Honoraria.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.008 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.003 | 0.003 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".