"Quantity Has a Quality All Its Own"

This post from my mentor complaining about the assembly-line workload doctors face got me thinking about a term I learnt from one of those Evidence-based Medicine workshops: Numbers Needed to Treat (NNT).

I failed biostatistics back in medical school, but I believe NNT means the number of patients you need to treat before one of them benefits from the treatment. Applying this to say stroke prevention, it means that a treatment with NNT of 10 means that for every 10 patients you treat, you would have prevented one stroke (which would have occurred if they were not given the treatment).

A more thorough explanation can be found at this site.

Let's say we take the figure from this article:

"Two studies of antihypertensive treatment in hypertensive people over 60 years have NNTs of about 40 to prevent one stroke over 4 years compared with placebo. This means that 40 people have to be treated for four years to prevent a stroke in one of them, who would have had a stroke if they had been given a placebo."

So say aliendoc sees 8 patients an hour, for 44 hours a week, and she works 46 week (14 gazetted holidays, 3 weeks leave, one week MC...) a year.

That makes 16,192 consultations.

Let's say half of those are acute cases like cough-and-cold, and that the rest are repeat visits for chronic illnesses like diabetes and hypertension, on 3-monthly visits.

That makes 2024 unique chronic patients.

Given that the prevalance of hypertension in Singapore is about 25%, and given a NNT of 40, that makes 12 strokes prevented.

That's one person saved from a stroke each month.

The numbers may not be exact, but I suspect the order of magnitude should be correct. And we haven't even counted the other complications like heart attacks, or the other chronic diseases like diabetes and high cholesterol.

So how many strokes have you prevented today?