As you can see from this imaginary scenario, the new test misdiagnosed 20 of the 100 people. These are true negatives (TN) – this is good too.įrom these kinds of tables you can work out how good a new/alternative diagnostic test is. These are false negatives (FN) – this is really bad! These are false positives (FP) – this is bad. ![]() These are true positives (TP) – this is good People tested who do have Disease X (n = 50) He then compares these results with his new test, which you can see in the table below. Using the gold standard he finds out that 50 people have the dreaded ‘Disease X’ and 50 people do not. The GP decides to compare a new test he’s just bought with the gold-standard perfect test. Let’s imagine 100 people come to a GP to get tested for ‘Disease X’. To understand what the results of this paper mean it is worth running through an imaginary scenario. The perfect test should be able to tell you everyone who has the disease and correctly identify everyone who does not have the disease…easier said than done. The studies were also screened for quality and bias.Īs outcomes they chose several different measures of diagnostic accuracy that can get a bit confusing. Two authors independently assessed the search results and used a standardised data extraction sheet. They searched MEDLINE, EMBASE, PsychoINFO and Google Scholar from the earliest available dates stated in the individual databases until. In terms of how the search was performed, it looks very thorough. Any patients who were visually impaired.Tests that were only evaluated in four or less papers.Tests that took longer than 20 minutes to complete.Published the outcome measures they were interested in.Used a standardised diagnostic criteria to diagnose dementia.Assessed patients or carers face-to-face.Looked for patients with either Alzheimer’s, vascular dementia or Parkinson’s disease in any clinical setting.This systematic review compares the MMSE with other tools for detecting dementia. Compared it to other measures that fell into three categories tests that took less than 5 minutes to complete, 10 minutes and 20 minutes.Assessed the performance of the MMSE at being able to correctly detect dementia and. ![]() In this paper, the authors completed a systematic review of the literature for studies that: One of the reasons to assess the relative merits of the MMSE is that it is a proprietary instrument, owned by ‘Psychological Assessment Resources’ meaning that it is not actually free for organisations to use. As the authors of this paper state, the performance of the MMSE in detecting dementia as compared to other tests has not been systematically assessed and so, that is what they set out to do. The test itself takes about 10 minutes to complete. In this test you can score up to 30 points by answering a range of questions that test your orientation to time and place, your memory, attention and so on. ![]() The commonest cognitive test used is called the Mini-Mental State Examination (MMSE). Obviously, an exhaustive assessment of a person’s cognitive function would take a very long time – hours, if not longer! While researchers may have hours to spend with patients, most busy clinicians do not and so the Holy Grail is finding a good, brief screening test of cognitive function that allows us to diagnose dementia. ‘Cognitive’ here means the ‘higher brain functions’ I alluded to earlier things like memory, numeracy, visual perception, personality change and planning, to name a few. The way we diagnose and detect dementia, therefore, is by systematically assessing the function of various brain regions by using cognitive tests. By comparison, frontotemporal dementia affects the frontal area of the brain first and, as a result, these patients often have changes in personality and difficulties in planning long before they have difficulties with memory. For this reason patients with Alzheimer’s disease get memory problems early on. For example, early on in the disease course Alzheimer’s affects an area of the brain called the hippocampus, which is involved in storing memories about our lives. The symptoms a particular person with dementia develops depends on where in the brain the disease is affecting. The symptoms and the impairment caused by dementia are a result of progressive damage to the brain and a loss of brain cells and connections. Alzheimer’s disease, for example, is the commonest cause of dementia. In this systematic review and meta-analysis, Tsoi and colleagues from Hong Kong aimed to assess the relative effectiveness of common cognitive tests at diagnosing dementia.ĭementia is an umbrella term for a number of different brain diseases that progressively affect a person’s ability to think and function independently.
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