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SpPIN – high specificity, Positive test Rule in.SnNOUT – high sensitivity, Negative test Rule out.When assessing sensitivity and specificity, remember the mnemonic: However, if the dipstick came back positive, she may actually have a UTI as the specificity is high (van Stralen et al., 2009). If a woman, whose symptomatology is suggestive of a UTI tests negative, would that mean that she does not have a UTI? With the sensitivity of the test being low, the clinician cannot tell. For example, the sensitivity and specificity of the nitrate dipstick is 27% and 94%, respectively. There are times when a clinician would want a test with low sensitivity and high specificity and vice versa. Likewise, a test that is highly specific is useful for ruling in a disease if one test is positive for it. It is important to remember that these are based on disease prevalence, which varies depending on the population being tested.Ī test that is highly sensitive is useful for ruling out a disease if one test is negative for it. The terms “sensitivity, specificity, and positive/negative predictive values” all refer the diagnostic utility of a certain test. However, most tests do not achieve such performance. A perfect clinical test would yield 100% sensitivity and specificity. Sensitivity refers to the ability of a test to correctly identify those patients who have the disease, whereas, specificity refers to the ability of a test to correctly identify those patients who do NOT have the disease (Akobeng, 2007). Sensitivity and specificity are two measures that evaluate the performance of medical tests. However, in reality, this may not be the case, as it may be the best test given the clinical picture at the time (Maxim, Niebo, & Utell, 2014). Ideally, gold standard tests, such as coronary angiography, breast biopsy, or colposcopy should have 100% sensitivity and specificity. Screening tests are less invasive and less costly, whereas the gold standard test may be more invasive, expensive, or too late (discovered during an autopsy). In this case, a prostate biopsy is considered a definitive test, as it will reveal the etiology of the elevated PSA. Positive results of screening tests need to be compared to the established gold standard test that is regarded as definitive. For example, a male with an elevated PSA may have prostate cancer, BPH, or prostatitis. Examples of screening tests include routine EKGs, PSA, PAP smears, and mammograms. The goal of screening tests is to reduce the morbidity and mortality in a population group (Maxim, Niebo, & Utell, 2014).

They are not definitive, but if positive, will heighten suspicion that would warrant use of a gold standard diagnostic test to rule in or rule out a certain diagnosis. Screening tests (surveillance tests) are tools use to assess the likelihood that a patient may have a certain disease. The purpose of this post is to explain the concept of sensitivity, specificity, predictive values, and likelihood ratios.