1. AJ Wagstaff, SJ Goodyear, IK Nyamekye Worcestershire Royal Hospital.
Risk adjusted DVT prophylaxis for ambulatory varicose vein procedures: How useful is the Caprini risk assessment model?
AJ Wagstaff, SJ Goodyear, IK Nyamekye
Worcestershire Royal Hospital.
American College of Phlebology’s 30th Annual Congress Anaheim, California
4th November 2016

2. Should LMWH Anti-DVT prophylaxis be used in Ambulatory VV patients?
VTE after Radiofrequency ablation
reported rates of 0-16%
significant morbidity and mortality
Venous thromboembolism is a recognised complication of ambulatory varicose vein procedures. There are incidence rates of 0-16% published in the literature. VTE prophylaxis is of clinical significance in this population of patients because VTE is associated with significant morbidity and mortality. As noted in these recent deaths following varicose vein procedures. Another case is currently being investigated by the coroner.

3. Role of LMWH Anti-DVT prophylaxis in Ambulatory VV patients?
VTE Prophylaxis in Venous Thermal Ablation
Variable practice (not evidence based)
Absent in major VTE guidelines
NICE 2013 CG 168
ACCP (SVS & AVF) 2012
SIGN 2010
LMWH use (UK)
Never Selective Always
As a result of variable incidence of VTE variable practice of VTE prophylaxis is observed. Some surgeons never us prophylactic LMWH, some always use it, with the majority selecting those patients deemed at highest risk at the discretion of the surgeon. This is underscored by the absence of specific guidelines published. SIGN is the only guideline to specifically mention endovenous procedure statiing LMWH/UFH should be used in the presence of additional risk factors.

4. Selecting patients for LMWH Anti-DVT prophylaxis in Endovenous procedures
Risk Assessment Models
-Procedure based: -Procedure type (minor/inter/major) -Duration (> 60mins/ > 90mins)
-Patient based -Caprini Score
-DoH Risk Assessment Tool
VTE risk may be established using a risk assessment model. Risk assessment models are either procedure or patient based.
Procedure based risk assessment models are determined by the procedure type and duration which are not useful for short endovenous procedures.
Patient based risk assessment models, such as the Caprini and DOH risk assessment tools were initially developed for patients undergoing major surgery, not day case varicose vein procedures.

5. Caprini Risk Assessment Model
Selecting patients for LMWH Anti-DVT prophylaxis in Endovenous procedures
Caprini Risk Assessment Model
Caprini scores & risk:
Low points
Moderate points
High points
Highest - ≥5 points
Caprini is a weighted risk assessment tool that classifies patients as either low, moderate, high or highest risk of VTE depending on the presence of various risk factors.
However only the shaded risk factors are applicable to patients undergoing short endovenous procedures.
Laryea, Champagne Clinics in Colon and Rectal Surgery Vol. 26 No. 3/2013

6. DoH Risk Assessment Tool
Selecting patients for LMWH Anti-DVT prophylaxis in Endovenous procedures
DoH Risk Assessment Tool
The DOH risk assessment tool is a national model used across the NHS. It is not a weighted tool and again only the shade risk factors are applicable to patients undergoing short endovenous procedures.
The RCOG have DOH model for obstetric patients in order to stratify patients as either high, intermediate or low risk of VTE depending on the clinical significance of each risk factor.

7. New ‘Worcester Risk Assessment Tool’
Selecting patients for LMWH Anti-DVT prophylaxis in Endovenous procedures
New ‘Worcester Risk Assessment Tool’
Targeted factors Score
Obesity (BMI >30) 1
Hormonal therapy 1
Active Thrombophlebitis 1
1ary /1st degree VTE 2
Reduced limb mobility 2
Thrombophilia 2
Worcester score & risk:
Low - 0 points
Moderate points
High - ≥2 points
The Worcester risk assessment tool is a proposed risk assessment tool specifically designed for endovenous procedures.
The presence of risk factors deemed clinically significant to this cohort of patients are scored. 1 point is score for obesity, hormonal therapy and active thrombophlebitis at the time of procedure. 2 points are scored for personal history of VTE, reduced limb mobility (classified as any factor that reduces calf muscle pump function) and a personal history of thrombophilia. This generates a score of 0, low risk, 1 point moderate risk and 2 or more points as high risk of VTE. SIMPLE

8. Comparison of Caprini, DoH and the new ‘Worcester Risk Score’
Aims
To determine
Whether the Caprini RAM is a useful predicative tool for VTE in patients undergoing local anaesthetic ambulatory varicose vein (LA-AVV) procedures
Whether Caprini score correlate with the clinical decision to administer prophylactic low molecular weight heparin (LMWH).
Compare Caprini, DOH and ‘Worcester risk score’.
Methods
A retrospective analysis of registry data
18 months 01/11/ /03/2016
Patients undergoing RFA
Clinical decision for LMWH
VTE events at 6 weeks (duplex)
Hormonal therapy (OCP or HRT)
Previous history of VTE
Known thrombophilia
Reduced mobility
Active thrombophlebitis
The aims of this study as set out in the abstract were to to determine whether Caprini RAM is a useful predictive tool for VTE in patients undergoing LAAVV and also whether the score correlated with the clinical decision to administer LMWH.
In addition to these initial aims we also compared the adapted DOH RAM and the proposed ‘WRS’ against the same outcomes of predicting an thromboembolic event and the decision to administer LMWH.
A retrospective analysis of registry data was reviewed over an 18 month period (6 months longer than the published results in the abstract). Only patients undergoing sole RFA were included. It was noted the clinical decision to treat prophylactically with LMWH. This decision was based upon use of hormonal therapy, previous history of VTE, known thrombophilia, reduced mobility and active thrombophlebitis. The outcome of VTE was recorded at 6 weeks post procedure on duplex imaging.
V1 2015/16

9. Results Comparison of Caprini, DoH and the new ‘Worcester Risk Score’
Patients
(n = 21)
BMI ≥30
Hormone Therapy
Thrombophlebitis
Hx VTE 5 X 4 3 1
Results
Patients Mean age yrs (19-88 yrs)
Sex (55%) women
LMWH - 21 (8%)
DVT/EHIT - 0/2 (0%/1%)
276 patients were treated during the 18 month period, with an average age of 55years and 55% of patients were women. 21 patients were treated prophylactically with LMWH. 20 of this patients received once daily clexane injections varying in duration from 5 days to 30 days. One patient was treated with fondaparinux 2.5mg for 30 days. Zero DVT occurred and two endovenous heat induced thrombosis occurred.
5 patients were treated due to active thrombophlebitis at the time of surgery, 5 patients were treated because of use of hormonal therapy, 4 patients were treated due to a personal history of VTE, 3 patients were treated due to use of hormonal therapy and raised BMI, 3 patients were treated due to raised BMI alone, 1 patient was treated due to raised BMI and active thrombophlebitis.

10. Caprini Risk Assessment and VTE Prophylaxis
No EHIT
EHIT
LMWH 4
103
This is a bubble chart of results. This and the following two slides are to be intepreted the same.
The blue bubbles represent the risk assessment groups. The red bubbles represent the occurance of an EHIT. The green bubbles above the dashed line represent the patients treated with prophylactic LMWH. The size of each bubble reflects the number of patients.
This bubble chart shows the results of Caprini risk assessment. 133, almost half the population of patients were classified as high or highest risk with caprini scores. Only 13% of these were treated prophylactically with LMWH. Of the two EHITs that occurred, one occurred in a low risk patient, and one occurred in a high risk patient.
V1 2015/16

11. DOH Risk Assessment and VTE Prophylaxis4
238
This bubble chart represents the DOH risk scores. 36 patients, 13% of the total population were classified as moderate or high risk. Just under half were treated prophylactically with LMWH. However both EHITs occurred in patients deemed low risk by the DOH score.
V1 2015/16

12. ‘Worcester Risk Score’ and VTE Prophylaxis
214
The bubble chart represents the proposed Worcester risk score. 60 patients, 22% of the population were classed as intermediate or high risk. Approximately a third were treated prophylactically with LMWH. This should not be surprising as the risk factors used to determine the clinical decision to treat prophylactically were used to form part of the worcester risk score. It is to be noted that both EHITs occurred in patients scored as high risk.
V1 2015/16

13. Discussion
There is no established risk assessment tool for VTE prophylaxis
Caprini Score is not predictive for DVT/EHIT or useful in risk stratification.
DOH score showed better agreement with the clinical decision to treat prophylactically. Was not predictive for DVT/EHIT.
The proposed ‘Worcester Risk Score’ predicted the two EHITs and may be a useful tool.
There is currently no established risk assessment tool for VTE prophylaxis in patients undergoing local anaesthetic ambulatory varicose vein procedures.
The caprini score was not predictive for DVT/EHIT nor usefull for risk straitifcation. If used it would lead almost half the patients receiving LMWH. The DOH score showed a better agreement with the clinical decision to administer VTE prophylaxis, however it was not predictive for DVT/EHIT with both events occuring in low risk patients.
The proposed ‘Worcester risk score’ predicted the two EHITs and may be a useful tool for risk stratifying this population of patients.

14. Risk adjusted DVT prophylaxis for ambulatory varicose vein procedures: How useful is the Caprini risk assessment model?
We did not find the Caprini RAM as a useful tool for predicting VTE in LA-AVV procedures
The proposed ‘Worcester Risk Score’ may be a more useful tool.
To conclude. We did not find the Caprini risk assessment model as a useful tool for predicting VTE in LA-AVV procedures
There is a need for a specific RAM in endovenous procedures.
The proposed WRS may be a more useful tool however further investigation.