Best testing strategy for DVT identified

News release from the National Coordinating Centre for Health Technology Assessment

23 May 2006

New research commissioned by the HTA programme has identified the most cost-effective ways for diagnosing deep vein thrombosis (DVT), clarifying an area of uncertainty for many UK hospitals. It suggests that there are two approaches, both involving a combination of clinical assessment, blood testing and ultrasound, that give the most clinically and cost-effective options for diagnosis of DVT in hospital. A survey of over 200 emergency departments carried out as part of the research found that while most hospitals had a testing protocol in place, there was great variation in practice. The strategies, published as part of the completed report, could provide a useful practical guide for medical staff to follow during DVT investigation. The study is published this week (22 May) in the Health Technology Assessment journal series Vol 10 no. 15 (http://www.hta.ac.uk/project.asp?PjtId=1340) and in the June issue of the Quarterly Journal of Medicine (to view the article, visit http://qjmed.oxfordjournals.org/cgi/content/full/99/6/377)

Led by Dr Steve Goodacre of the Medical Care Research Unit, University of Sheffield, the research team carried out a systematic review of existing research evidence to assess the performance of different non-invasive diagnostic tests for DVT. The team examined accuracy, and clinical and cost-effectiveness of the different tests. They included clinical assessment (using a Wells scoring system), a blood test for D-dimer, plethysmography and rheography techniques, ultrasound, CT and MRI scanning, and venography, which is traditionally regarded as the reference standard. The researchers also sent surveys to 255 UK hospitals, asking them to describe current practice and availability of tests, and to identify any testing strategies already in place.

The researchers found that two particular strategies (referred to in the report as algorithms nine and 16), both using a combination of Wells score, D-dimer and above-knee ultrasound, were the most cost-effective, and would be feasible in UK hospitals without substantial reorganisation of services. One strategy (algorithm 16) involved discharging patients with a low or intermediate Wells score and negative D-dimer; ultrasound for those with a high score or positive D-dimer; and repeat scanning for those with positive D-dimer and a high Wells score, but negative initial scan. A more expensive but similar strategy (algorithm nine) would involve repeat ultrasound for all those with a negative initial scan.

Survey responses established that most hospitals were using some sort of testing strategy, and of the 61 hospitals that provided details of their strategy, three-quarters were using a combination of the above tests. However, there were differences in the protocols they followed. Some advised no further testing for patients with a low Wells score, whereas others advised D-dimer or ultrasound.

"The algorithms identified in the study provide a clear guide that could be followed by NHS service providers to ensure a consistent approach,” says Dr Goodacre. “More research could be carried out to investigate the practicalities of implementing them throughout the NHS, such as how the algorithms perform in different groups of patients and when they are implemented by different providers."

Notes:

  1. 186 out of the 255 hospitals surveyed responded (73 per cent response rate)

  2. Algorithms nine and 16 are set out in full in Health Technology Assessment (Volume 10.15) the internationally acclaimed journal of the HTA programme. The full text of the research monograph is available for download free of charge from: www.hta.ac.uk. This research will also be published in the Quarterly Journal of Medicine in June. To view the article, visit http://qjmed.oxfordjournals.org/cgi/content/full/99/6/377 

Notes for editors


  1. The HTA programme is a programme of the National Institute for Health Research (NIHR) and produces high quality research information about the effectiveness, costs, and broader impact of health technologies for those who use, manage and provide care in the NHS. It is the largest of the NIHR programmes and publishes the results of its research in the Health Technology Assessment journal, with more than 400 issues published to date. The journal’s 2007 Impact Factor (3.87) ranked it in the top 10% of medical and health-related journals. All issues are available for download free of charge from the website, www.hta.ac.uk The HTA programme is coordinated by the National Coordinating Centre for Health Technology Assessment (NCCHTA), based at the University of Southampton.
  2. The National Institute for Health Research provides the framework through which the research staff and research infrastructure of the NHS in England is positioned, maintained and managed as a national research facility.  The NIHR provides the NHS with the support and infrastructure it needs to conduct first-class research funded by the Government and its partners alongside high-quality patient care, education and training.  Its aim is to support outstanding individuals (both leaders and collaborators), working in world class facilities (both NHS and university), conducting leading edge research focused on the needs of patients. www.nihr.ac.uk

Contact details

Naomi Stockley, Programme Manager (Communications)
Telephone: 02380 595 646, Email: ns5@soton.ac.uk

Helen Nikandrou, Assistant Programme Manager (Communications)
Telephone: 02380 595 584, Email: h.nikandrou@soton.ac.uk

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