Age-adjusted D-dimer excludes pulmonary embolism and reduces unnecessary radiation exposure in older adults: retrospective study

Application of the pulmonary embolism rule-out criteria (PERC rule) and age-adjusted D-Dimer in patients undergoing computed tomography pulmonary angiography for diagnosis of pulmonary embolism

Background

Diagnosis of pulmonary embolism (PE) constitutes a challenge for practitioners. Current practice involves use of pre-test probability prediction rules. Several strategies to optimize this process have been explored.

Objectives

To explore whether application of the pulmonary embolism rule-out criteria (PERC rule) and age-adjusted D-dimer (DD) would have reduced the number of computed tomography pulmonary angiography (CTPA) examinations performed in patients with suspected PE.

Methods

A retrospective cross-sectional study of adult patients taken for CTPA under suspicion of PE in 2018 and 2020. The PERC rule and age-adjusted DD were applied. The number of cases without indications for imaging studies was estimated and the operational characteristics for diagnosis of PE were calculated.

Results

302 patients were included. PE was diagnosed in 29.8%. Only 27.2% of 'not probable' cases according to the Wells criteria had D-dimer assays. Age adjustment would have reduced tomography use by 11.1%, with an AUC of 0.5. The PERC rule would have reduced use by 7%, with an AUC of 0.72.

Conclusions

Application of age-adjusted D-dimer and the PERC rule to patients taken for CTPA because of suspected PE seems to reduce the number of indications for the procedure.

Age-Adjusted D-Dimer in the Prediction of Pulmonary Embolism: Systematic Review and Meta-analysis

Background:

Pulmonary embolism (PE), depending on the severity, carries a high mortality and morbidity. Proper evaluation, especially in patients with low probability for PE, is important to avoid unnecessary diagnostic testing.

Objective:

To review the diagnostic utility of conventional versus age-adjusted D-dimer cutoff values in patients 50 years and older with suspected pulmonary embolism.

Methods:

Systematic review with univariant and bivariant meta-analysis.

Data sources:

We searched PubMed, MEDLINE, and EBSCO for studies published before September 20th, 2020. We cross checked the reference list of relevant studies that compares conventional versus age-adjusted D-dimer cutoff values in patients with suspected pulmonary embolism.

Study selection:

We included primary published studies that compared both conventional (500 µg/L) and age-adjusted (age × 10 µg/L) cutoff values in patients with non-high clinical probability for pulmonary embolism.

Results:

Nine cohorts that included 47 720 patients with non-high clinical probability were included in the meta-analysis. Both Age-adjusted D-dimer and conventional D-dimer have high sensitivity. However, conventional D-dimer has higher false positive rate than age-adjusted D-dimer.

Conclusion:

Age-adjusted D-dimer cutoffs combined with low risk clinical probability assessment ruled out PE diagnosis in suspected patients with a decreased rate of false positive tests.

Role of a new age-adjusted D-dimer cutoff value for preoperative deep venous thrombosis exclusion in elderly patients with hip fractures

Objective

This study aimed to describe the characteristics of plasma D-dimer level with increasing age and establish a new age-adjusted D-dimer cutoff value for excluding preoperative lower limb deep vein thrombosis (DVT) in elderly patients with hip fractures.

Methods

This was a retrospective study of elderly patients who presented with acute hip fracture in our institution between June 2016 and June 2019. All patients underwent D-dimer test and duplex ultrasound. Patients were divided into six 5-year-apart age groups. The optimal cutoff value for each group was calculated by using receiver operating characteristic (ROC) curves, whereby the new age-adjusted D-dimer cutoff value was determined. The sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) were calculated and compared when different D-dimer cutoff values were applied, i.e., conventional 0.5 mg/L, previously well-established age-adjusted cutoff value (age × 0.01 mg/L) and the new age-adjusted D-dimer cutoff value herein.

Results

There were 2759 patients included, 887 males and 1872 females, with an average age of 78 years. In total, 280 patients were diagnosed with preoperative DVT. The optimal cutoff values for the six age groups were 0.715 mg/L, 1.17 mg/L, 1.62 mg/L, 1.665 mg/L, 1.69 mg/L and 1.985 mg/L, respectively, and the calculated age-adjusted coefficient was 0.02 mg/L. With this new coefficient applied, the specificity was 61%, clearly higher than those for conventional threshold (0.5 mg/L, 37%) or previously established age-adjusted D-dimer threshold (age × 0.01 mg/L, 22%). In contrast, the sensitivity was lower than that (59% vs 85% or 77%) when D-dimer threshold of 0.5 mg/L or age-adjusted cutoff value (age × 0.01 mg/L) was used. The other indexes as PPV (15%, 11% and 12%) and NPV (93%, 93% and 94%) were comparable when three different D-dimer thresholds were applied.

Conclusions

We developed a new age-adjusted D-dimer cutoff value (age × 0.02 mg/L) for a specified high-risk population of patients aged 65 years or older with hip fractures, and demonstrated the improved utility of the D-dimer test for exclusion of DVT. This formula can be considered for use in elderly hip fracture patients who meet the applicable standards as preoperative DVT screening, after its validity is confirmed by more well-evidenced studies.

Machine learning with D-dimer in the risk stratification for pulmonary embolism: a derivation and internal validation study

AIM

To develop a machine learning model to predict the diagnosis of pulmonary embolism (PE).

METHODS AND RESULTS

We undertook a derivation and internal validation study to develop a risk prediction model for use in patients being investigated for possible PE. The machine learning technique, generalized logistic regression using elastic net, was chosen following an assessment of seven machine learning techniques and on the basis that it optimized the area under the receiver operator characteristic curve (AUC) and Brier score. Models were developed both with and without the addition of D-dimer. A total of 3347 patients were included in the study of whom, 219 (6.5%) had PE. Four clinical variables (O2 saturation, previous deep venous thrombosis or PE, immobilization or surgery, and alternative diagnosis equal or more likely than PE) plus D-dimer contributed to the machine learning models. The addition of D-dimer improved the AUC by 0.16 (95% confidence interval 0.13-0.19), from 0.73 to 0.89 (0.87-0.91) and decreased the Brier score by 14% (10-18%). More could be ruled out with a higher positive likelihood ratio than by the Wells score combined with D-dimer, revised Geneva score combined with D-dimer, or the Pulmonary Embolism Rule-out Criteria score. Machine learning with D-dimer maintained a low-false-negative rate at a true-negative rate of nearly 53%, which was better performance than any of the other alternatives.

CONCLUSION

A machine learning model outperformed traditional risk scores for the risk stratification of PE in the emergency department. However, external validation is needed.

Age adjusted D-dimer cutoffs for pulmonary embolism in a geriatric population utilizing a D-dimer unit assay

BACKGROUND

Age adjusted serum d-dimer (AADD) with clinical decision rules have been utilized to rule out pulmonary embolism (PE) in low-risk patients; however, its use in the geriatric population has been questioned and the use of d-dimer unit (DDU) assay is uncommon.

OBJECTIVE

The present study aims to compare the test characteristics of the AADD (age × 5) measured in DDU with the standard cutoff (DDU < 250) and study hospital laboratory's d-dimer cutoff (DDU < 600) in geriatric patients presenting with suspected PE.

METHODS

This retrospective study enrolled patients ≥65 years old with suspected PE and d-dimer performed between January 1, 2019 and December 31, 2019 who presented to the emergency department (ED). Charts were reviewed for CTA chest and ventilation perfusion imaging results for PE. Diagnostic parameters for each cutoff were calculated for the primary outcome.

RESULTS

510 patients were included, 20 with PE. There was no significant difference between the sensitivities of AADD (100%, 95% CI: 80-100), standard cutoff (100%, 95% CI: 80-100), and hospital cutoff (90%, 95% CI: 66.9-98.2). The hospital cutoff specificity (22.7%, 95% CI: 17.1-29.3) was significantly greater than the AADD (13.4%, 95% CI: 9.1-19.2) and standard cutoff (10.8%, 95% CI: 7.0-16.3) specificities.

CONCLUSIONS

In geriatric patients presenting to the ED with suspected PE, the AADD measured in DDUs maintained sensitivity with improved specificity compared to standard cutoff. In this population, the AADD would have safely reduced imaging by 19% without missing any PEs. AADD remains a valid tool with high sensitivity and negative predictive value in ruling out PE in geriatric patients.

Diagnostic Accuracy of D-Dimer Testing and the Revised Geneva Score in the Prediction of Pulmonary Embolism

BACKGROUND

Pulmonary embolism (PE) diagnosis can sometimes be challenging due to the disease having nonspecific signs and symptoms at the time of presentation. The present study aimed to evaluate the validity of the D-dimer in combination with the revised Geneva score (RGS) in the prediction of pulmonary embolism.

PATIENTS AND METHODS

This is a retrospective study of 2010 patients with suspected PE who had undergone both D-dimer testing followed by chest CT angiography (CTPA), irrespective of the D-dimer test results, at King Abdulaziz Medical City, Riyadh, Saudi Arabia, over 3 years, from Jan. 2016 to Jan. 2019. The predictive accuracy of D-dimer, adjusted D-dimer, and RGS was calculated. The receiver operating characteristic "ROC" curve was applied to allocate the optimum RGS cutoff for PE prediction.

RESULTS

The overall prevalence of PE was 16%. It was 0%, 25.8%, and 88.9% in low, intermediate, and high clinical probability categories of RGS, respectively. Both conventional and age-adjusted D-dimer thresholds showed significant level of agreement (kappa=0.81, p<0.001), high sensitivity (94% and 92.8%), high negative predictive value "NPV" (91.2% and 91.4%), low specificity (12.3% and 15.3%), and low positive predictive value "PPV" (17.5% and 17.8%), respectively. Combination of the age-adjusted D-dimer threshold and RGS at a cut-off of 5 points would provide 100% sensitivity and 61.7% specificity 34.1% PPV, 100% NPV, and 0.87 area under the curve "AUC". At an RGS cutoff <5 points, PE could have been ruled out in more than one-half (1036, 51.5%) of all suspected cases, and would have saved the cost of CTPA.

CONCLUSION

Conventional and age-adjusted D-dimer tests showed high levels of agreement in the prediction of PE, high sensitivity, and low specificity. RGS has a good performance in PE prediction. Using the revised Geneva score alone rules out PE for more than one-half of all suspected without further imaging.

The diagnostic value of D-dimer with simplified Geneva score (SGS) pre-test in the diagnosis of pulmonary embolism (PE)

Background

Pulmonary embolism (PE) is the third most common cardiovascular syndrome with an average annual incidence rate of 77 per 100,000 population in the worldwide. The diagnose algorithms for suspected PE are generally include clinical scoring assessment and plasma D-dimer evaluation, patients with high risk of PE require computed tomographic pulmonary angiogram (CTPA) detection for confirmation.

Methods

In this retrospective analysis, 1035 patients with suspected PE were recruited. All the patients were clinically received simplified Geneva score (SGS) pre-test, determination of plasma D-dimer level, and CTPA detection. All enrolled patients were grouped according to the CTPA results: PE patients and non-PE patients. Then, receiver operating characteristic (ROC) curve were constructed to determine the optimal D-dimer cutoff point value which is based on Yonden’s index (YI).

Results

294 (28.4%) patients were confirmed with PE and 741(71.6%) individuals were regarded as non-PE cases by CTPA detection. Using the SGS pre-test, 829 (80.1%) patients were classified PE-unlikely (SGS ≤ 2) and 206 (19.9%) patients were PE-likely (SGS ≥ 3). Patients with D-dimer levels above 1.96 mg/L had a significant risk to suffer from PE (area under curve (AUC), 0.707; 95% CI, 0.678–0.735; p < 0.05). Meanwhile, in patients with SGS ≥ 3, the D-dimer cutoff point value moved to 2.2 mg/L (AUC, 0.644; 95% CI, 0.574–0.709; p < 0.05).

Conclusion

D-dimer test in combination with SGS pre-test could improve the accuracy of PE diagnosis. Patients with D-dimer levels over 1.96 mg/L (4 times of the normal level) have a significant risk for PE. In patients with SGS ≥ 3, the D-dimer cutoff point concentration for PE risk moves to the levels of 2.2 mg/L.

Predictive Model for Pulmonary Embolism in Patients with Deep Vein Thrombosis

BACKGROUND

To develop and verify a risk predictive model/scoring system for pulmonary embolism (PE) among hospitalized patients with deep venous thrombosis of the lower extremities (LDVT).

METHODS

776 patients with LDVT were enrolled in a case-control study between January 2016 and June 2017 from the Vascular Surgery Department of Shanxi Dayi Hospital, China. They were randomly divided into development (543 patients, 70%) and validation (233 patients, 30%) databases. Based on the results of pulmonary computed tomography arteriography, patients were divided into 2 categories; those with PE were designated as the case group, whereas those without comprised the controls. A logistic regression model and scoring system for PE in patients with LDVT was established in the development database and verified in the validation database. Scoring system (Shanxi Dayi Hospital score [SDH score]) was tabulated as follows: right lower extremity or bilateral lower extremities, 1; surgery or immobilization, 1; malignant tumor, 1; history of venous thromboembolism (VTE), 2; D-dimer >1,000 ng/mL, 2; and unprovoked, 2. Calibration and discrimination of the model were assessed by the Hosmer-Lemeshow goodness of fit test and the area under the receiver operating characteristic curve (AUC). Wells score, the Revised Geneva score, and the SDH score for predictive value of PE by AUC in the validation database were compared.

RESULTS

776 patients with LDVT were divided into 2 risk categories based on the scores from the risk model as follows: PE unlikely (score <3) and PE likely (score ≥3). Sensitivity, specificity, and crude agreement of the SDH score in the development database were 76.39%, 55.89%, and 61.33%, respectively. In the validation database, the logistic regression model showed good calibration and discriminative power. The Hosmer-Lemeshow goodness of fit test P value was >0.05, and the AUC was 0.705 (95% CI: 0.634-0.776, P < 0.001). The SDH score also showed good discriminative power, and the AUC was 0.702 (95% CI: 0.631-0.774, P < 0.001). Sensitivity, specificity, and crude agreement of the SDH score in the validation database were 67.61%, 61.73%, and 63.52%, respectively. AUC for the Wells score and the Revised Geneva score was 0.611 (95% CI: 0.533-0.688, P = 0.007) and 0.585 (95% CI: 0.503-0.666, P = 0.040), respectively. Difference of the AUC was not statistically significant between the Wells score and the SDH score (0.611 vs. 0.702, P = 0.059) but was so between the Revised Geneva score and the SDH score (0.585 vs. 0.702, P = 0.016). Sensitivity of the Wells score, Revised Geneva score, and the SDH score (64.79%, 67.61% vs. 67.61%) was not statistically significant. However, the specificity of the Wells score and Revised Geneva score was significantly lower than that of the SDH score (48.77%, 39.51% vs. 61.73%).

CONCLUSIONS

Our logistic regression model and the SDH score based on 7 risk factors as right lower extremity, bilateral lower extremities, unprovoked, surgery or immobilization, malignant tumor, history of VTE, and D-dimer>1,000 ng/mL showed good calibration and discriminative power for the assessment of PE risk in patients with LDVT. The SDH score is more specific for PE prediction in the Chinese population, compared with the Wells score and the Revised Geneva score.

ECG in suspected pulmonary embolism

Objective

To establish the diagnostic value of prespecified ECG changes in suspected pulmonary embolism (PE).

Methods

Retrospective case–control study in a district general hospital setting. We identified 189 consecutive patients with suspected PE whose CT pulmonary angiogram (CTPA) was positive for a first PE and for whom an ECG taken at the time of presentation was available. We matched these for age±3 years with 189 controls with suspected PE whose CTPA was negative. We considered those with large (n=76) and small (n=113) clot load separately. We scored each ECG for the presence or absence of eight features that have been reported to occur more commonly in PE.

Results

20%–25% of patients with PE, including those with large clot load, had normal ECGs. The most common ECG abnormality in patients with PE was sinus tachycardia (28%). S1Q3T3 (3.7%), P pulmonale (0.5%) and right axis deviation (4.2%) were infrequent findings. Right bundle branch block (9.0%), atrial dysrhythmias (10.1%) and clockwise rotation (20.1%) occurred more frequently but were also common in controls. Right ventricular (RV) strain pattern was significantly more commonly in patients than controls, 11.1% vs 2.6% (sensitivity 11.1%, specificity 97.4%; OR 4.58, 95% CI 1.63 to 15.91; p=0.002), particularly in those with large clot load, 17.1% vs 2.6% (sensitivity 17.1%, specificity 97.4%; OR 7.55, 95% CI 1.62 to 71.58; p=0.005).

Conclusion

An ECG showing RV strain in a breathless patient is highly suggestive of PE. Many of the other ECG changes that have been described in PE occur too infrequently to be of predictive value.

Diagnostic utility of an age-specific cut-off for d-dimer for pulmonary embolism assessment when used with various pulmonary embolism risk scores

This retrospective cohort study compared the diagnostic utility (sensitivity, specificity and negative predictive value (NPV)) of the age-times-10 adjusted d-dimer cut-off used in combination with the original and simplified Well's pulmonary embolism (PE) scores and the original and simplified revised Geneva scores to identify patients in whom PE is classified as unlikely according to each score. The PE risk scores performed similarly with high sensitivity (97.6, 97.1, 96.9 and 97.1% respectively) and NPV (99.3, 99.3, 99.2 and 99.2% respectively). Each missed only one PE. The age-times-10 age-adjusted d-dimer assay cut-off performed similarly with each of the clinical risk scores tested with high sensitivity and NPV.

Use of the d-dimer for Detecting Pulmonary Embolism in the Emergency Department

BACKGROUND

Assessment for pulmonary embolism (PE) in the emergency department (ED) remains complex, involving clinical decision tools, blood tests, and imaging.

OBJECTIVE

Our objective was to examine the test characteristics of the high-sensitivity d-dimer for the diagnosis of PE at our institution and evaluate use of the d-dimer and factors associated with a falsely elevated d-dimer.

METHODS

We retrospectively collected data on adult patients evaluated with a d-dimer and computed tomography (CT) pulmonary angiogram or ventilation perfusion scan at two EDs between June 4, 2012 and March 30, 2016. We collected symptoms (dyspnea, unilateral leg swelling, hemoptysis), vital signs, and medical and social history (cancer, recent surgery, medications, history of deep vein thrombosis or PE, chronic obstructive pulmonary disease, smoking). We calculated test characteristics, including sensitivity, specificity, and likelihood ratios for the assay using conventional threshold and with age adjustment, and performed a univariate analysis.

RESULTS

We found 3523 unique visits with d-dimer and imaging, detecting 198 PE. Imaging was pursued on 1270 patients with negative d-dimers, revealing 9 false negatives, and d-dimer was sent on 596 patients for whom negative Pulmonary Embolism Rule-Out Criteria (PERC) were documented with 2% subsequent radiographic detection of PE. The d-dimer showed a sensitivity of 95.7% (95% confidence interval [CI] 91-98%), specificity of 40.0% (95% CI 38-42%), negative likelihood ratio of 0.11 (95% CI 0.06-0.21), and positive likelihood ratio of 1.59 (95% CI 1.53-1.66) for the radiographic detection of PE. With age adjustment, 347 of the 2253 CT scans that were pursued in patients older than 50 years with an elevated d-dimer could have been avoided without missing any additional PE. Many risk factors, such as age, history of PE, recent surgery, shortness of breath, tachycardia and hypoxia, elevated the d-dimer, regardless of the presence of PE.

CONCLUSIONS

Many patients with negative d-dimer and PERC still received imaging. Our data support the use of age adjustment, and perhaps adjustment for other factors seen in patients evaluated for PE.

Age-adjusted D-dimer to rule out deep vein thrombosis: findings from the PALLADIO algorithm

Essentials The accuracy of the age-adjusted D-dimer in suspected venous thromboembolism is still debated. We assessed the performance of age-adjusted D-dimer combined with the PALLADIO algorithm. The age-adjusted threshold can reduce the need for imaging tests compared to the fixed cut-off. The safety of this approach should be confirmed in large management studies.

SUMMARY

Background Age-adjusted D-dimer has been proposed to increase specificity for the diagnosis of venous thromboembolism (VTE). However, the accuracy of this threshold has been recently questioned. Objectives To assess the diagnostic performance of age-adjusted D-dimer combined with clinical pretest probability (PTP) in patients with suspected deep vein thrombosis (DVT). Methods PALLADIO (NCT01412242) was a multicenter management study that validated a new diagnostic algorithm, incorporating PTP, D-dimer (using the manufacturer's cut-off) and limited or extended compression ultrasonography (CUS) in outpatients with clinically suspected DVT. Patients with unlikely PTP and negative D-dimer had DVT ruled out without further testing (group 1); patients with likely PTP or positive D-dimer underwent limited CUS (group 2); patients with likely PTP and positive D-dimer underwent extended CUS (group 3). Patients with DVT ruled out at baseline had a 3-month follow-up. In this post-hoc analysis we evaluated age-adjusted D-dimer cut-off (defined as age times 10 μg L-1 , or age times 5 μg L-1 for D-dimers with a lower manufacturer's cut-off, in patients > 50 years). Results In total, 1162 patients were enrolled. At initial visit, DVT was detected in 4.0% of patients in group 2 and 53.0% in group 3. The age-adjusted D-dimer, compared with the fixed cut-off, resulted in 5.1% (95% CI, 4.0-6.5%) reduction of CUS. The incidence of symptomatic VTE during follow-up was: 0.24% (95% CI, 0.04-1.37) in group 1; 1.12% (95% CI, 0.44-2.85) in group 2; and 1.89% (95% CI, 0.64-5.40) in group 3. Conclusions The PALLADIO algorithm using age-adjusted D-dimer slightly decreased the number of required imaging tests, but this approach should be confirmed in large management studies.