NNT Number needed to treat.

Streptokinase is a clot busting drug.

From the ISIS2 trial, using streptokinase and aspirin after myocardial infarction had an NNT of 20 to prevent 1 death at 5 weeks compared with doing nothing. Here is prophylaxis against a serious event, by definition not treatable if it occurs. The NNT for the adverse effect of haemorrhagic stroke with streptokinase was 1000.

From the less dramatic end of the spectrum is prophylaxis after dog bite. If no prophylactic antibiotics are given any subsequent infection (10%) should be treatable. The NNT for antibiotic prophylaxis was 16, so that only one patient out of 16 receiving prophylaxis actually avoids infection as a result. The other 15 have antibiotics that they did not need, and which may have adverse effects. And then there is cost.

I got the quotes above from Bandolier. Great medical site full of evidence based stuff. NNT is a useful concept. Is treating 20 people to save one life worthwhile - most people are going to says yes. At what cost?

Is it worthwhile treating 16 people with dog bites to prevent one infection. I'd say no. What would you say?

With regards to streptokinase I'd prefer to know the results at a year and even five years. Many people lived for many years after having a heart attack prior to clot busting drugs. Could giving clot busting drugs have a deleterious effect on long term survival? If for sake of argument they save 1 in 20 at five weeks but at a year 2 extra treated persons are dead compared to non treated, what choice would you make? Does anyone know what the figures are two or more years out.