D-Dimer in Elderly

[DrQuinn]

Doing a quick poll re: D-Dimer in the Elderly, for a little quality improvement project I've been working on.

Q

---

Members don't see this ad.

 

[lucky_deadman]

Doing a quick poll re: D-Dimer in the Elderly, for a little quality improvement project I've been working on.

Q

I think it's use in this patient population is similar to that in other groups. A lot of whether I'm getting one or not depends on the pre-test probability.

 

[WilcoWorld]

There are certain populations I don't order d-dimers on:

1 - Patient's with too high of a pretest probability for me to stop at a d-dimer (Hx of PE/DVT that was not situational (such as a DVT s/p ORIF 15 years ago with no recurrence since) or a great story + risk factors).

2 - Patient's in who I know it will be elevated for other reasons (active infection, active rheumatologic conditions, etc).

3 - Patients who have low risk via PERC & who I have a low suspicon of. I document absence of all PERC & don't order any PE tests - I think this is every bit as defensible as basing my decision on a negative d-dimer.

Usually if d-dimer is + I follow it up with a CT or VQ, but occasionally I get it with the 1st blood draw & if in the mean time another condition declares itself I might not pursue the d-dimer.

 

[Hercules]

There are certain populations I don't order d-dimers on:

1 - Patient's with too high of a pretest probability for me to stop at a d-dimer (Hx of PE/DVT that was not situational (such as a DVT s/p ORIF 15 years ago with no recurrence since) or a great story + risk factors).

2 - Patient's in who I know it will be elevated for other reasons (active infection, active rheumatologic conditions, etc).

3 - Patients who have low risk via PERC & who I have a low suspicon of. I document absence of all PERC & don't order any PE tests - I think this is every bit as defensible as basing my decision on a negative d-dimer.

Usually if d-dimer is + I follow it up with a CT or VQ, but occasionally I get it with the 1st blood draw & if in the mean time another condition declares itself I might not pursue the d-dimer.

That pretty much sums up my approach as well.

 

[roja]

Yup. just got done going over LR, NPP and sensitivity of ddimers in elderly patients.


Elderly does not factor into pretest probability, so much, in and of itself.

You must be wary of using negative predictive values in HIGH prevelance populations (in any test). That is why in a LOW PROB patient the NPV is useful but in a moderate to high prob patient, it is USELESS. You can't use NPV in a moderate to high prob patient. (regardless of if you determine the pretest prob using wells or clinical gestalt like pioped)

This is a confusing concept and residents get it confused alot (I did as well until I started teaching it over and over again)

 

[waterski232002]

There are certain populations I don't order d-dimers on:

1 - Patient's with too high of a pretest probability for me to stop at a d-dimer (Hx of PE/DVT that was not situational (such as a DVT s/p ORIF 15 years ago with no recurrence since) or a great story + risk factors).

2 - Patient's in who I know it will be elevated for other reasons (active infection, active rheumatologic conditions, etc).

3 - Patients who have low risk via PERC & who I have a low suspicon of. I document absence of all PERC & don't order any PE tests - I think this is every bit as defensible as basing my decision on a negative d-dimer.

Usually if d-dimer is + I follow it up with a CT or VQ, but occasionally I get it with the 1st blood draw & if in the mean time another condition declares itself I might not pursue the d-dimer.

Agree with above....

 

[DrQuinn]

I've always been taught that a D-Dimer in anyone age > 60 tends to normally be elevated (I've done a literature search and found that the average DDimer in asymptomatic elderly is ~600), so therefore the test becomes useless. If it is negative, it still is negative and a good screening exam, but the false positives are far higher than need be.

Hence, I don't order DDimers in anyone over 60.

Interesting to see others on here with opposite feelings.

Q

 

[EctopicFetus]

I've always been taught that a D-Dimer in anyone age > 60 tends to normally be elevated (I've done a literature search and found that the average DDimer in asymptomatic elderly is ~600), so therefore the test becomes useless. If it is negative, it still is negative and a good screening exam, but the false positives are far higher than need be.

Hence, I don't order DDimers in anyone over 60.

Interesting to see others on here with opposite feelings.

Q

can you get me a link to that article or tell me cwho the authors were.

 

[anothertbmember]

I've always been taught that a D-Dimer in anyone age > 60 tends to normally be elevated (I've done a literature search and found that the average DDimer in asymptomatic elderly is ~600), so therefore the test becomes useless. If it is negative, it still is negative and a good screening exam, but the false positives are far higher than need be.

Hence, I don't order DDimers in anyone over 60.

Interesting to see others on here with opposite feelings.

Q

I've been taught by someone with your same views.

 

[DrQuinn]

can you get me a link to that article or tell me cwho the authors were.

Evaluation of D-dimer ELISA test in elderly patients with suspected pulmonary embolism.
Tardy B, Tardy-Poncet B, Viallon A, Lafond P, Page Y, Venet C, Bertrand JC.

Department of Emergency Medicine, CHRU Bellevue, Saint-Etienne, France.

STUDY OBJECTIVE: To determine the clinical usefulness of D-dimer ELISA test in elderly patients with clinically suspected pulmonary embolism (PE). DESIGN: Prospective cohort study. PATIENTS: Ninety-six consecutive outpatients older than 70 years with a duration of symptoms shorter than one week and without metastatic cancer or recent surgery, trauma, infection, stroke, myocardial infarction, deep vein thrombosis (DVT) or PE, or treatment with curative doses of heparin or oral anticoagulant. INTERVENTION: All patients underwent at least ventilation/perfusion scan and bilateral ultrasonic duplex scan and a blood sample collection within 24 hours of admission. When necessary a pulmonary angiography and/or a bilateral venography were also performed. Patients were classified as follows: (1) PE-positive: positive angiography or high probability V/Q scan and deep vein thrombosis (proven either by venography or by ultrasonic duplex scan) or non high probability V/Q scan and either DVT (proven at presentation by venography or by ultrasonic duplex scan) or symptomatic thromboembolic event within 3 months of follow-up; or (2) PE-negative; normal V/Q scan or normal angiography or non high probability V/Q scan and either negative ultrasonic duplex scan or normal venography and low clinical probability and absence of symptomatic thromboembolism within 3 months of follow-up. D-dimer measurements were performed using both a conventional and a single semi-quantitative ELISA test (Asserachrom D-di, Instant I.A.D-dimer). RESULTS: Using a cutoff value of 500 ng/ml, the conventional ELISA D-dimer test showed a sensitivity and a negative predictive value of 100% with poor specificity and positive predictive value of 14.3% and 45.5% respectively. The new rapid semi-quantitative D-dimer test displays worse results with sensitivity, negative predictive value, specificity and positive predictive value of 92.3%, 82.4%, 25% and 46% respectively. CONCLUSION: In a geriatric population, conventional ELISA D-dimer is a good marker to exclude PE but, due to the comorbid conditions, only a few patients presented with D-dimer values less than 500 ng/ml.



Or this one:

D-dimer concentration increases with age reducing the clinical value of the D-dimer assay in the elderly

* P. L. Harper,11Department of Haematology, Palmerston North Hospital, Palmerston NorthP. L. Harper, Department of Haematology, Palmerston North Hospital, Heretaunga Street, Palmerston North, New Zealand.
Email: [email protected]
* E. Theakston,22Diagnostic Medlab, Auckland
* J. Ahmed33Department of Medicine, Auckland City Hospital, Auckland, New Zealand and
* P. Ockelford22Diagnostic Medlab, Auckland

*
1Department of Haematology, Palmerston North Hospital, Palmerston North, 2Diagnostic Medlab, Auckland and 3Department of Medicine, Auckland City Hospital, Auckland, New Zealand

P. L. Harper, Department of Haematology, Palmerston North Hospital, Heretaunga Street, Palmerston North, New Zealand.
Email: [email protected]

Funding: None

Potential conflicts of interest: None
Abstract


Background: The D-dimer assay is used as an exclusion test in the assessment of suspected venous thromboembolic disease; patients with a negative result have a low probability of thrombosis. We reviewed the D-dimer results from a hospital and community laboratory using the vidas D-dimer test to assess the influence of age on the D-dimer assay.

Methods: D-dimer results from 6631 unselected patients aged more than 16 years were analysed in four age groups and it was shown that the median D-dimer concentration increased with age (16–40 years, 294 ng/mL; 40–60 years, 387 ng/mL; 60–80 years; 854 ng/mL; >80 years, 1397 ng/mL). To test the effect of age on the assay specificity, a cohort of 1897 patients with suspected venous thromboembolic disease was analysed separately. Patients with a negative D-dimer were discharged without further investigation. Patients with a positive result and a clinical suspicion of thrombosis underwent further investigation. One hundred and sixty-five deep vein thrombosis or pulmonary embolus cases were identified.

Results: The assay specificity decreased with age from 70% in patients less than 40 years to below 5% in patients more than 80 years. Receiver operator curves were prepared for each age group and the effect of altering the threshold value was analysed. In patients 60–80 years old a threshold value of 1000 ng/mL increased assay specificity to 55% without loss of assay sensitivity.

Conclusion: The vidas D-dimer assay with a threshold value of 500 ng/mL has little clinical value as an exclusion test in patients more than 80 years old. The assay specificity is poor (26%) in patients aged 60–80 years but could be improved by increasing the threshold value to 1000 ng/mL. We believe that this should be tested in a prospective trial.

 

[lucky_deadman]

Thanks for the articles. Interesting reading. Sounds like it could be a good area for further study.

Although I'm sure the contrast does more harm to their old kidneys than does the radiation; it would be nice to eliminate CT PE scans just because of an elevated D-dimer level that may be normal for age.