{"id":1260,"date":"2016-03-02T21:01:21","date_gmt":"2016-03-02T20:01:21","guid":{"rendered":"https:\/\/blogs.bmj.com\/adc\/?p=1260"},"modified":"2016-03-30T09:53:02","modified_gmt":"2016-03-30T08:53:02","slug":"how-often-can-you-cry-wolf","status":"publish","type":"post","link":"https:\/\/blogs.bmj.com\/adc\/2016\/03\/02\/how-often-can-you-cry-wolf\/","title":{"rendered":"How often can you cry “Wolf”?"},"content":{"rendered":"

\"\"<\/a>The fable of the bored shepherd boy, alone on a hillside (except for the sheep – sheep don’t count as company*) waiting for something to happen, is one that I hope most of us know and can recount if needed at any dinner table.<\/p>\n

In my folk-recollections of the tale, it’s three times that the lad calls “Wolf!”. Twice he gets the thrill of a village-load of yokels pounding out to his hillside vantage point, and it’s the third – truthful\u00a0– one that everyone ignores and the sheep get gobbled up.<\/p>\n

How many times can we call “Wolf!” on a ward and get away with it? Or – how good does a PEWS need to be before we’ll think it’s useful?<\/p>\n

<\/p>\n

The shepherd’s actually pretty damned good. A 33% hit rate would be considered remarkable by most folk wanting an alert about a life-threatening condition. What would be the acceptable lower limit though?<\/p>\n

Is 25% good enough<\/p>\n

– 20%?<\/p>\n

— 10%?<\/p>\n

—- 5%?<\/p>\n

—— 2%?<\/p>\n

There’s a recent paper that evaluates the NHS-PEWSIII <\/a>in a cohort of patients in Wales\u00a0and gets a 2% positive predictive value. Combine this with the recent evidence summary<\/a> on PEWS-like systems and you’re in a bit of a dilemma – if it seems to work but is terribly tiring, how can it\u00a0really work in real wards?<\/p>\n

(There’s a similar issue with referrals with lymphadenopathy in particular for suspected lymphoma, with the “two week wait” systems being shown repeatedly [1<\/a> 2<\/a> 3<\/a>] to have a very low positive predictive value. In this instance, the NICE guideline<\/a> states explicitly than in adults it’s working with a 2% threshold and that in children it should\u00a0be considerably lower.)<\/p>\n

What is the right way to think about induced\u00a0complacency vs. the value of an early warning system? Is the issue just because of scarse resource, or something else?<\/p>\n

How many times can we call “Wolf!”<\/p>\n