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NICE nonsense on clot prevention

December 13, 2011

Bad enough for medical patients. Worse in pregnancy

NICE (the National Institute for Clinical Excellence) recommends that all hospital inpatients be assessed for risk of venous thrombo-embolism (VTE) and, if at high risk, prescribed preventative measures, mostly heparin injections to thin the blood. Hospitals are fined if they fail to risk assess at least 90% of patients.

In this weeks BMJ (click here) consultant Mark Welfare questions whether the figures for VTE mortality are accurate, and if the treatment really works. He suspects the whole thing is driven by companies flogging heparin and that the targets are diverting doctors from better things.  He’s probably right on all counts.

But he ignores pregnant women, so let me fill in the gap. The same guidelines insist that they also be risk assessed, and heparin considered above a certain (modest) risk score, even in the antenatal period and as outpatients. Heparin is not risk free; it causes bleeding, occasional immune reactions and brittle bones. For some patients the benefits outweigh the harms, but it’s a close calculation for which good evidence is needed.

The evidence?  None! Nil! Zilch! The number of antenatal patients ever randomised to heparin or placebo for VTE prevention is precisely zero!

I guess it’s just about acceptable to extrapolate from trials in non-pregnant adults to women who have just delivered. At least then the heparin is unlikely to harm the baby. Ditto for women giving birth by Caesarean.  But giving heparin to large numbers of pregnant women in the absence of any evidence from randomised trials that it does more good than harm.  Have we learned nothing from the di-ethylstiboestrol, thalidomide and hormone replacement therapy scandals?

Don’t misunderstand me. Some women have terrible histories and risky treatments have to be given in the absence of clear evidence. But we have super specialists to look after them. NICE VTE risk scoring is not about that.

It’s about the many thousands of more or less normal women who have two or three risk factors. Things like being overweight, aged over 35, having raised blood pressure, varicose veins, carrying twins, or having a relative with VTE. It’s a long list.

The guidelines are careful to limit their recommendation to “consider” heparin thrombo-prophylaxis; the authors know perfectly well that there is no hard evidence. But all over the country these guidelines are being turned into risk assessment scores with a target completion rate of 90%. The qualifying statements are missing or unread, and many busy obstetricians just write the prescription. Heparin is given to many more patients than it ever used to be.

The cost?  It’s not just the money. Another check sheet lies in the notes impeding access to the stuff that really matters, a few more seconds are spent ticking boxes or tapping on the computer instead of engaging with the patient, and much more heparin with all its attendant risks is prescribed. Whatever happened to primum non nocere?

Jim Thornton

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