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James The approach that I described was a summary. I would be prepared to provide as much detail as available such as risk percentages. However the latter are of dubious validity as I have explained already (for example due to the widespread misapplication of relative risk and the dichotomising of test results into normal or abnormal instead of considering the actual test result). My problem solving approach is to regard a negative screening result as I would a transient minor symptom of little significance. I treat a positive result as a significant symptom and investigate it in the usual way. I would also share my thoughts and the decision with the patient in the usual way. I agree with you Stanley that a screening test is fundamentally different from a symptom. The presence of a symptom means that any subsequent NNT is likely to be low if it is alleviated. However an asymptomatic positive screening test result is going to have a high NNT because the patient may never develop a symptom anyway. This is basically the difference between a screening test result and a symptom. However the clinical reasoning is the same for both. Huw > On 5 Dec 2018, at 22:40, McCormack, James <[log in to unmask]> wrote: > > Huw - this is all tricky as it gets very nuanced - what I meant by "discussing false positives etc” I really meant to suggest that there needs to be a discussion about the fact that screening tests don’t always give black and white answers - however one best does that, > > I have a big issue with saying something like “epidemiologists” state "probability of anything serious is low and that it is generally accepted that no further action need be taken” > > “Serious” does not mean the same thing to everyone > “Low" is not defined and the use of the words like low/high etc have been shown to be misleading at best > "Generally accepted” is very paternalistic - to believe that a group of epidemiologists can judge what is important or not important for everyone is IMHO the wrong approach > > It gets back to arbitrary thresholds > > I know patients who think that a 1% absolute reduction in CVD events from a statin is pretty good for them, I also know people who think a 10% absolute benefit is not much of an effect for them. How in the world can any group of epidemiologists deal with these differing values and preferences? > > James > > > > > >> On Dec 5, 2018, at 2:15 PM, Huw Llewelyn [hul2] <[log in to unmask]> wrote: >> >> I don’t think many patients would understand FP and FN. Even I find them to be obscure terms that can be misleading and confusing to those with no specialist knowledge. >> >> Personally, would say that the ‘negative’ test result was below some recognised cut-off point arrived at by epidemiologists and indicated that the estimated probability of anything serious is low and that it is generally accepted that no further action need be taken. If the patient requested the evidence behind this recommended decision in order to share in it I would try to provide it. >> >> If the test was positive, I would give it’s actual value, the possible causes (ie differential diagnoses) of that particular value and how they should be investigated. I never use the terms FP and FN. >> >>> On 5 Dec 2018, at 21:37, Donald E. Stanley <[log in to unmask]> wrote: >>> >>> Do any of you believe that patients can accommodate FP and F N? >>> >>> Dr. Donald E. Stanley FCAP >>> Associates in Pathology >>> 500 West Neck Road >>> Nobleboro, ME. 04555 >>> [log in to unmask] >>> >>> >>>> On Dec 5, 2018, at 16:19, Huw Llewelyn [hul2] <[log in to unmask]> wrote: >>>> >>>> To >>> CONFIDENTIALITY NOTICE: This email message, including any attachments, is for the use of the intended recipient(s) only and may contain information that is privileged, confidential, and prohibited from unauthorized disclosure under applicable law. If you are not the intended recipient of this message, any dissemination, distribution, or copying of this message is strictly prohibited. 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