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Our labs were complaining for a long time about the waste of money & time they spent doing lab d-dimers (? elisa i think). £30,000 of so, often for inpatients. We offered to take it over and run the d-dimer testing from the ED - no inpatients, they all have raised d-dimers anyway. To use the SIMLIFY test kit, permission is required from the ED registrar - the gatekeeper. We use simplify, which I believe has 98% negative predictive value, (with due regard to simon's infinitely more scientific posting), and is very easy to use - no need to refridgerate, foolproof to read. Only bin going three months so no audit data yet.Needless to say though, it is clear that inappropriate use of the test is a fraction of what it was previously so we get a better test, immesurably quicker and I believe higher neg predictive value than the lab one. SteeveMeek Bath We only use it for PE, as part of a risk strat as simon and others said. We do not use it for DVT - I thought the evidence ws lacking for a use in dvt - am I wrong? --- "s.carley" <[log in to unmask]> wrote: > Well they might!!!! > > It all depends on where you put the cut off and > which test you use. This is > something that has not yet been discussed. With a > continuous value such as > d-dimer level (or CKMBmass, or amylase etc. etc.) > the ability of the test to > rule out or rule in depends on where you put the > marker. For example a > CKMBmass on our testing less than 5 is pretty good > at ruling out AMI (or > less than 3 rise & with reference to timings), but > at this level it has poor > rule in value (you probably need to get above 8). > > There is also quite a lot of variation between > different tests. It is not > fair to compare SimpliRED against lab based > quantitive assays (except in a > trial) for example. > > Anyway we constantly interpret such tests as yes/no > values. For example a > d-dimer of 270 is negative, whereas one of 279 is > positive. Rubbish!! it > just means that one of those results makes a DVT/PE > slightly more likely. It > is definately not positive/negative. > > So in our example if we set the d-dimer cut off at 5 > then it would work, > though it would be no use in practice at all.(very > sensitive but not > specific enough). That is the thrust behind using > the results of thes tests > in the context of a clinical risk stratification. By > manipulating the > pretest probability in a structured manner you get > much more benefit out of > your test. > > Wouldn't it be nice if all continuous data tests > like these were given with > two values, a rule in and a rule out level. And in > the middle it is > equivocal and you need to do more work, or another > test. Interestingly many > levels are set at the point at which they are most > "accurate", i.e. a > compromise of sensitivity against specificity. Where > is the sense in that! > It does not reflect our clinical practice. > > Simon > Hi Ho Silver (hobby horse) > > Simon Carley > SpR in Emergency Medicine > [log in to unmask] > Evidence based emergency medicine > http://www.bestbets.org > ----- Original Message ----- > From: "Dunn Matthew Dr. ACCIDENT & EMERGENCY - > SwarkHosp-TR" > <[log in to unmask]> > To: <[log in to unmask]> > Sent: Thursday, October 18, 2001 10:07 AM > Subject: Re: re-d dimers > > > > To clarify my previous post: our haematologists > tell us that negative > > d-dimers do rule out a DVT regardless of clinical > findings. This seems to > > differ from other respondents. > > > > Matt Dunn __________________________________________________ Do You Yahoo!? Make a great connection at Yahoo! Personals. http://personals.yahoo.com