Sir.

The recent article on the introduction of inducements to prescribe VTE prophylaxis for both surgical and medical patients seems strange and misconceived (1). The statement that most cases of deep venous thromboses can be prevented, at least as far as medical patients are concerned, is simply wrong. The recently published meta analysis shows that symptomatic DVT occurred in 0.79% of patients given prophylaxis with heparin versus 0.96% in controls. (1). Therefore I believe the management of John Hopkins Hospital and NICE should review its recommendation that heparin or fondaparinux be offered to patients admitted to hospital for medical conditions other than stroke as prophylaxis against Venous Thromboembolism (VTE) (2). This is as the aforementioned meta analysis and a recently published study (4) shows that there is no statistically significant reduction in overall mortality, for VTE prophylaxis in medical patients.

This result is not surprising given that the reduction in symptomatic VTE is the same as the increase in bleeding for in patients given heparin compared with controls (2). In the light of NICE guidance on how risks and benefits are presented to patients the advice that pharmacological prophylaxis should be offered to general medical patients is perplexing (5). In my view, patients admitted to hospital with a medical condition excluding stroke should be counselled as follows: The chance of you developing a clot in your veins during your present admission that would cause you symptoms such as pain and swelling in your leg is around 10 in a 1000 and the chance of dying from a clot lodging in one of your main blood vessels in the next 3 months is about 3 in a thousand. If you have a daily injection this may reduce these risks to about 8 in a thousand and 2 in a thousand, respectively, but the chance of bleeding would increase from 27 to 47 in a thousand and the chance of having a serious (life threatening) bleed from 2 in a thousand too around 3 in a thousand.

If you are medically qualified or of a scientific bent then you may like to consult the table below taken from a recently published Meta analysis (2) together with a recent study published in the New England Journal of Medicine (3). Thus you can see that the effect on mortality and morbidity is very small: with an absolute reduction in overall mortality from 6.6% to 6.5%; odds ratio 0.94 (95% C.I.84-1.04.) and symptomatic DVT 0.96% to 0.79% OR 0.78 (95% C.I.0.45-1.35).

I doubt, given this information that many patients would take up the offer of heparin injections. I think most doctors would have grave doubts about prescribing prophylactic heparin with at best such a marginal benefit, particularly when they consider that the benefits outlined above are almost certainly an overestimate given the significant publication bias found in the meta-analysis (2), and there is no validated tool with which to estimate the risk of bleeding.

References:
1. Streiff MB, Carolan HT, Hobson DB et al. Lessons from the John Hopkins Multi-Disciplinary Venous Thromboembolism (VTE) Prevention Collaborative. BMJ 2012; 344: e3935.
2. Lederle FA, Zylla D, MacDonald R and Wilt TJ. Venous thromboembolism prophylaxis in hospitalized medical patients and those with stroke: a background review for an American College of Physicians Clinical Practice Guideline. Ann Intern Med 2011;155:602-615

3. National Institute for Health and Clinical Excellence: Venous Thromboembolism Reducing the Risk www.nice.org CG 92.

4. Kakkar AK, Cimminiell C, Goldhaber SZ et al. Low-Molecular-Weight Heparin and Mortality in Acutely Ill Medical Patients. N Engl J Med 2011;365:2463-72.

5. National Institute for Health and Clinical Excellence: Patient Experience in Adult NHS Services www.nice.org CG 138.

Competing interests: None declared