SERVICE SPECIFICATION FOR TREATMENT OF SUSPECTED DEEP VEIN THROMBOSIS (DVT) IN PRIMARY CARE. Redditch and Bromsgrove Commissioning Cluster.

Transcription

1 SERVICE SPECIFICATION FOR TREATMENT OF SUSPECTED DEEP VEIN THROMBOSIS (DVT) IN PRIMARY CARE Redditch and Bromsgrove Commissioning Cluster mmmm

2 CONTENTS: 1. Background 2. Aims of Service 3. Clinical Features of a DVT 4. Risk Factors for DVT 5. Diagnosis of DVT 6. Rationale for Treatment 7. Treatment Regimes for DVT 8. Patient Pathways 9. Location of Service / Premises 10. Core Skills / Competencies of Staff 11. Benefits to Service Recipients 12. Key Relationships with Other Services 13. Measurable Targets 14. Activity Monitoring & Data Requirements 15. Contracting Currency 16. Commencement Date of Service 17. Review Date 18. Service Specification Prepared by 19. Service Specification Endorsed by 20. References Appendix 1: Clinical Probability Scoring Appendix 2: Dosage Guidelines Appendix 3: Patient Pathway

3 1. Background Acute deep vein thrombosis (DVT) is a common and potentially life threatening disorder. It occurs with an annual frequency of per thousand population. Pulmonary embolism, which is now generally regarded as part of the same spectrum of disease, occurs at about half this frequency (Booth, F 2003). Historically, there has been a standard pathway for patients seen by GPs in Worcestershire with a suspected DVT, but this has only applied to four Bromsgrove practices. 2. Aims of Service To improve the standard of care and patient experience To provide a cost effective service which delivers value for money To deliver care closer to home negating the need for admissions to MAU To standardise and streamline proccesses across the health economy 3. Clinical Features of a DVT The diagnosis of a DVT is usually suspected in patients who complain of a painful swollen limb. However, the clinical picture can vary widely and none of the clinical features is sufficiently specific to be diagnostic. Less than a third of patients referred for tests after initial history and clinical examination prove to have a DVT. Clinical diagnosis is notoriously difficult. Common presenting features include: Pain or tenderness of the leg Oedema above and/or below the knee Palpable venous thrombosis Increased temperature in the leg Fever Discoloration or erythema of the leg Venous distension 4. Risk Factors for DVT Possible predisposing factors are: Recent surgery Recent injury or trauma Previous DVT Recent immobility (> 24 hours) Long haul air flight Obesity or excess weight Oestrogen therapy Underlying malignant disease Family history thrombosis Known thrombophilic defect.

4 5. Assessment and Diagnosis of DVT Diagnosis of a DVT can only be achieved using imaging ie Doppler ultrasound or venography. The likelihood of having a DVT can be assessed using clinical probability scoring, although user variation and lack of inclusion of family history undermine the usefulness of this to exclude a DVT. D-dimer testing can exclude the possibility of a DVT and hence reduce the need for Doppler assessment. However a positive result cannot confirm a DVT and hence it is not diagnostic. 5.1 Clinical Probability Scoring The most widely used of the pre-test clinical probability screening models is that developed by Wells at al (1998). It is based on: Signs and symptoms The presence of risk factors for VTE The presence or absence of an alternative diagnosis at least as likely as DVT. Each element is assigned one or more positive or negative points (Appendix 1). The resultant points then determine if the diagnosis of DVT is of a high, intermediate or low probability. A high probability can be used to avoid the need for a d-dimer test with progression directly to Doppler assessment. 5.2 Laboratory tests (D-Dimer) D-Dimers are a specific breakdown product of cross-linked fibrin, released during fibrinolysis. The main object of the D-Dimer test is to detect situations of thrombin activation and fibrin formation. Venous thrombotic embolism (VTE) results in raised levels of D-Dimers. The D-Dimer test currently used in Worcestershire Acute Hospitals Trust requires the collection of venous blood to be sent to the pathology laboratory. D-Dimer is performed on a standard citrated blood sample (prothrombin tube pale blue top). A D-Dimer score of 280 and above is considered to indicate a possible diagnosis of DVT. However, a positive D-Dimer does NOT confirm the diagnosis of DVT. Fibrin is produced by a wide variety of conditions such as cancer, inflammation, infection and necrosis and the D-Dimer test is therefore not very specific for VTE. It is however, used as an aid to diagnosis. Points to note: D-Dimers are of less value in very elderly patients D-Dimers are of no value in the immediate post-operative period (within 2 weeks of any significant surgery) Patients with a high clinical probability score could be referred for ultrasound scan without D-Dimer testing

5 5.3 Imaging for DVT Doppler Ultrasound scan has become the investigation of choice in diagnosis of DVT. It will detect more than 90% of proximal DVT s (i.e. popliteal vein and above). It is less sensitive for calf vein thrombosis (about only 50% are detected) but pulmonary embolism from this site is rare and unlikely to cause significant haemodynamic disturbance even if it occurs. Venography is considered the reference standard investigation for DVT and is considered when ultrasound studies are equivocal for proximal vein thrombosis. 6. Rationale for Treatment Untreated proximal vein thrombosis (popliteal vein and above) carries a 40-50% risk of pulmonary embolism. This can be largely prevented by prompt and effective anticoagulation. Isolated calf vein thrombosis can extend proximally in 20-30% of cases, and although the risk of pulmonary embolism is very small, the risk of proximal extension can be eliminated by anticoagulant therapy. LMWH produces an immediate anticoagulant effect whereas oral anticoagulants act slowly and their effect builds up over 2-3 days. As a consequence, initially heparin, followed by oral anticoagulation, is associated with significantly less extension of thrombosis and embolism than in oral anticoagulation therapy alone. LMWH is usually given for between 4 and 7 days. In the community setting, Low Molecular Weight Heparin (LMWH) is given. It is given on a weight-adjusted basis, by subcutaneous injection once daily. The patient needs to be weighed so that the correct dose of LMWH can be prescribed. Dosage guidelines are attached at appendix 2. Continuation therapy is usually with warfarin oral anticoagulation. 7. Treatment Regimes for DVT 7.1 Physical Methods of Treatment There is no evidence that bed rest is necessary for the treatment of DVT (Partsch& Blattler, 2000; Kahn et al 2003) Rest may be helpful in the early stages of treatment and elevation of the leg (supported at the heel) when at rest may help reduce swelling. Graduated compression hosiery may be helpful in reducing the incidence of post-thrombotic syndrome. They need to be well fitted and worn for up to 2 years after a DVT. However, not all patients comply with the need to wear them for an extended period. NB. These are contra-indicated in patients with peripheral vascular disease. Adequate analgesia should be offered. Early mobilisation Good hydration Avoid venous obstruction wherever possible

6 7.2 Duration of Anticoagulation Therapy This is according to the risk recurrence of venous thrombosis. Low risk patients with reversible risk factors such as surgery, trauma, temporary immobilisation, travel, oestrogen therapy and pregnancy can probably be treated with anticoagulants for 4-6 weeks after the risk factors cease to be present. Intermediate risk patients have other (usually medical) risk factors or idiopathic thrombosis and are anticoagulated for at least 3-6 months. High risk patients include those who have permanent risk factors for DVT, e.g. cancer, permanent immobilisation, thrombophilia and those who have had recurrent venous thromboembolism. These patients are treated with anticoagulants indefinitely. 8. Patient Pathway The patient pathway is shown as a flow chart attached as appendix 3. Existing out of hours arrangements, will continue with district nursing teams administering clexane to patients at home. 9. Location of Service / Premises The service will be delivered in GMS / PMS premises. There are no specialist building or equipment requirements. 10. Core Skills / Competencies of Staff No specialist skills are required. 11. Benefits to Service Recipients No visits to MAU Improved access with care closer to home Improved patient experience 12. Key Relationships with Other Services GPs, Haematologists, DVT Clinic, GP Out of Hours service and District Nurses all need to work together to ensure a semaless pathway for the patient. 13. Measurable Targets Number of patients administered clexane in primary care Number of patients presenting at MAU for administration of clexane 14. Activity Monitoring & Data Requirements The primary care provider should record the number of patients for whom they have administered clexane and produce quarterly reports for charging purposes. The PCT will periodically audit the records kept in primary care.

7 15. Contracting Currency Unit price. Cost per case. 150 per case. This figure will: Pay for the extra time required from doctors and practice staff. Reward the increased responsibility taken on by the practice. Encourage high uptake (and hence increased savings) Provide a 50% reduction in costs compared to admission to MAU 16. Commencement Date of Service 1st March This scheme has been running effectively in Bromsgrove for many years and therefore there should be minimal obstacles in extending this to the rest of the RBCC area. 17. Review Date Quarterly during first year of operation and annually thereafter. 18. Service Specification Prepared by: Gio Caranci, Steve Miskin, Ian Morrey. GPs, Redditch and Bromsgrove Commissioning Cluster We wish to acknowledge the work done in producing the PCT document Patient pathway for the management of patients with deep vein thrombosis (DVT) in the community setting 19. Service Specification Endorsed by: RBPBCC practices 20. References 1. Booth, F. (2003). Draft information on diagnosis of DVT. Worcestershire Acute Hospitals Trust 2. Kahn, S et al (2003). Acute effects of exercise in patients with previous deep vein thrombosis. Chest Journal.org 3. Partsch, H & Blattler, W (2000). Compression and walking versus bed rest in the treatment of proximal deep vein thrombosis with low molecular

8 weight heparin. Journal of Vascular Surgery 4. Wells et al (1998). A simple clinical model for the diagnosis of deep-vein thrombosis combined with impedance plethysmography:potential for an improvement in the diagnostic process. J. Intern Med. Jan;243(1) : Clinical Probability Scoring Appendix 1

9 Feature Score if feature present Active cancer (treatment within 6 months or palliation) 1 Paralysis, paresis or recent plaster immobilisation of leg 1 Recently bed-bound for > 3 days or major surgery 1 within 4 weeks Localised tenderness along the deep veins 1 Entire leg swollen 1 Calf swelling 3cms more than asymptomatic side (at 1 10cms below tibial tuberosity) Pitting oedema confined to the symptomatic leg 1 Dilated superficial veins (non varicose) 1 Previously documented DVT 1 Alternative diagnosis as likely or greater than DVT -2 NB. In patients symptomatic in both legs, use the more symptomatic leg Score of 2 or more = DVT likely Score of 1 or less = DVT unlikely This model has a predictive value for proximal DVT of: 28% if DVT likely 6% if DVT unlikely Source: Wells et al (1998). Appendix 2 Low Molecular Weight Heparin Dosage Guidelines Enoxaparin (Clexane)

10 Dosage:1.5mg/kg bodyweight by subcutaneous injection ONCE DAILY for at least 5 days, and until adequate oral anticoagulation established. Once INR reaches 2.0 for 2 consecutive days on Warfarin therapy, please discontinue Enoxaparin Patient weight in (Kg) Treatment of Deep Vein Thrombosis Dose from Hospital protocol that will be initially prescribed (Enoxaparin in mg) Rounded dose to administer using 150mg/1ml syringes USE mg SCALE ON SYRINGES ONLY (each small graduation = 3mg) 40 60mg od 60mg od 45 68mg od 69mg od 50 75mg od 75mg od 55 83mg od 84mg od 60 90mg od 90mg od 65 98mg od 99mg od mg od 105mg od mg od 114mg od mg od 120mg od mg od 129mg od mg od 135mg od mg od 144mg od mg od 150mg od N.B. Patients > 100kg will require a combination of 2 syringes mg od 159mg (150mg plus 9mg) mg od 165mg (150mg plus 15mg) mg od 174 mg (150mg plus 24mg) mg od 180mg (150mg plus 30mg) mg od 189mg (150mg plus 39mg) mg od 195mg (150mg plus 45mg)