RecommendationBe aware that heparins are of animal origin and this may be of concern to some patients*. For patients who have concerns about using animal products, consider offering synthetic alternatives based on clinical judgement after discussing their suitability, advantages and disadvantages with the patient.
* See “Religion or belief: a practical guide for the NHS”, website:
Trade off between clinical benefit and harmsDifferent prophylaxis methods have different levels of evidence of efficacy and safety in different populations. Ideally, the choice of agent should be based on the most evidence-based and cost-effective agent for a given population. However, in situations where there are strong patient concerns, these need to be discussed openly.
Economic considerationsWhere a choice of agents is provided within a recommendation this is based either on the results of the cost-effectiveness model for that population, or on the extrapolation of cost- effectiveness results in other populations. In these circumstances the guideline development group were unable to conclusively state which of the strategies were the most cost-effective. Another of the reasons for local factors to influence choice of drug is that the contract prices (and therefore cost- effectiveness) of some of the drugs vary considerably between NHS Trusts.
Other considerationsWhile it is important to offer patients alternatives if there are concerns about using animal based products, it is also important that patients are aware of the clinical benefits or disadvantages (if any) of using these alternative products. If religious beliefs are a source of concern, the patients should be aware of the official stand of religious bodies about the product. Patients will only be able to make a good decision if they have a complete picture of the pros and cons of using these products. Where information is available, it will be useful to direct the patients to these information sources. There is information for patients with specific concerns e.g: “Porcine Derived Products” booklet which is refered to in the Department of Health document titled Religion or belief: a practical guide for the NHS” (available from http://www​​/en/Publicationsandstatistics​/Publications​/PublicationsPolicyAndGuidance​/DH_093133).
If the relative risks and benefits are explained to the patient (e.g. that fondaparinux may not be as effective as heparin), and the decisions clearly documented in the patient’s notes, the patient is perfectly within their rights to choose a less effective option, however difficult that might be for the clinician who wants to provide the best care.

From: 32, Provision of information to patients and planning for discharge

Cover of Venous Thromboembolism
Venous Thromboembolism: Reducing the Risk of Venous Thromboembolism (Deep Vein Thrombosis and Pulmonary Embolism) in Patients Admitted to Hospital.
NICE Clinical Guidelines, No. 92.
National Clinical Guideline Centre – Acute and Chronic Conditions (UK).
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