Results and learning’s from the DVT pathway implementation
Sarah Hyder, RCpNRegional Nurse Leader
Background•Greater Auckland Integrated Health Network (GAIHN) was established in 2010, to improve primary and secondary care integration and increase regional capacity within primary care to reduce avoidable hospital referrals •Auckland Regional Clinical Pathways (ARCP) sits within GAIHN workstream 3, enablers of better individual primary care
•DVT was one of 10 pathways developed within the ARCP group
Context• Primary care rule chosen as specifically for primary care. Used in Amsterdam since 2009
•Clearview Simplify PoC test used locally in NZ in the laboratory setting, familiarity with product
•Similar to Clearview pregnancy test used widely in primary care
•Discussed within pathway group and knowledge centre (WDHB) regarding need to pilot locally
Introduction•The ARCP for DVT was implemented on July 2nd 2012
•Phased roll out approach, training to practices prior to utilising the new pathway
•100 practices were initially trained across the Auckland metro region
•All cases received through POAC, ability to audit and measure pathway in one central location
Within several weeks there were reported cases of negative PoC tests ( Low risk, not investigated) where the patient then represented with a proven venous thrombotic event on USS:
• 2 gastrocnemius vein clots, close to popliteal vein junction. Treated with therapeutic Clexane
• 2 proximal DVT- treated with 6 months Warfarin• 1 distal DVT-treated with 6 months Warfarin
2 additional cases of extensive superficial thrombophlebitis requiring treatment were not included in these numbers
It was therefore decided to remove the kits from general practice and to run parallel testing in a controlled laboratory environment to gauge the depth of the problem
Table 1-Clinical Pathway using Clearview PoC tests
101 patients with
Suspected DVT
29 72
Negative PoC
Positive PoC
24 5
Positive on USS
8 64
Explanation of the parallel lab testing•The clinical pathway was amended and the D-dimer portion of the clinical variable score removed•Score of 4 or more went straight forward for USS• If the patient scored 3 or less then the patient was sent for a quantitative laboratory D-dimer (CA 7000)• This same sample was also tested on the qualitative Clearview simplify PoC test at the same time in the laboratory by experienced lab tech staff
The Clearview Simplify D-dimer test has a cut off of 800ug/L which is slightly higher than the quantitative laboratory cut off of 500ug/L used currently in the Auckland region
For the purpose of this evaluation we used the higher cut off of 800ug/L when evaluating the parallel testing results
A sub analysis using the lower cut off was used and this is discussed (additional results to consider) section
200 laboratory D-
dimers
132 68
128 4 12 56
Negative PoC Positive PoC
Control Lab tests-parallel qualitative tests
Positive USS
Additional results to considerOf the 200 laboratory parallel samples tested:
• 19 had a quantitative lab dimer result >800ug/L where the qualitative test was negative (9.5%). 3 had DVT on USS• An additional 23 results were negative on the
qualitative PoC test where the lab cut off of >500ug/L was used (11.5%). 1 had a proven DVT on USS• 40 had a quantitative lab dimer result >800ug/L
where the qualitative test was weak positive. • In the 2nd set of parallel lab tests 2 different
qualitative kits were used from the same lab sample. There were variances noted between the 2 results in 13 samples. Although this is a small number, it is interesting to note.
Results summary
Primary care Laboratory
Sensitivity 0.61 0.8Specificity 0.27 0.69 NPV 0.82 0.97
Discussion• PoC test performed to the level specified by the
manufacturers in the laboratory controlled tests. In general practice we were unable to accept the reduced sensitivity recorded and it was agreed unanimously by the group we could not reintroduce the test for safety reasons• Potential to swap PoC for quantitative lab D-dimer. Delays
with results, age related D-dimer rise. Rule validated with PoC, not evidenced based• Agreed to revert to Wells risk stratification. This is what
Canterbury use currently and most GP’s are familiar with Wells• Potential for a pilot of the Primary Care Rule this year
within the new Integrated Family Health Centre (IFHC) Health New Lynn, Totara Health• Abstract submitted to International Society of Thrombosis
and Haemostasis (ISTH) conference. Accepted as an oral presentation, July 2013 Amsterdam
Pathway Learning's•Training process for PoC testing, train the trainer
•The need to recognise clinical guidelines do not override clinical judgment
•Need for pathway implementation process for any pathway developed
Next Steps•GAIHN are currently recruiting for a clinical pathway development and implementation Project Manager within workstream 3, enablers of better individual care (eReferrals, Shared Care Plan, Access to diagnostics)
•Oral presentation of research undertaken to be presented in July 2013, Schiphol, Amsterdam
•DVT development group to explore pilot of PoC test within the IFHC, to be facilitated through POAC
Lessons learned•Pilot locally, Amsterdam is not Auckland New Zealand!
•Cautionary approach with implementation of pathways. Process, audit and measure essential to success
•Training process within practices mandatory for users of new PoC equipment
Thank you to all members of the DVT pathway development group for your commitment and hard work on this project. Your time and expertise is greatly appreciated.
References1.Lensing AW, Prandoni P. Prins MH, Buller HR. Deep vein
thrombosis. Lancet. 1999;353:479-85 (PMID: 99897352. ten Cate-Hoek AJ Prins MH. Management studies using a combination of D-dimer test result and clinical probability to rule out venous thromboembolism: a systemic review. J Thromb Haemost. 2005;3:2465-70 (PMID: 161500493. Wells PS, Owen C, Doucette S, Fergusson D, Tran H. Does this patient have deep vein thrombosis? JAMA. 2006;295:199-207. (PMID: 164039324.Tagelagi M, Elley CR. Accuracy of the Wells Rule in diagnosing deep vein thrombosis in primary health care. NZMJ 2007;120:12615. Oudega R, Moons K, Hoes A. The Wells Rule does not adequately rule out deep venous thrombosis in Primary acre Patients. Ann Intern med. 2005;143:100-76.Buller, H et al. Safely ruling out deep vein thrombosis in Primary Care. Ann Intern med. 2009;150:229-2357. Ministry of Health. 2011. Better, Sooner, More Convenient Health Care in the Community. Wellington: Ministry of Health. Retrieved from http://www.health.govt.nz/publication/better-sooner-more-convenient-health-care
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