dear all
- The first step in understanding a test is to assess the ability of the test to correctly diagnose the diseased and nondiseased. Sensitivity and specificity are test characteristics that help to access the ability of the test to make that distinction in an individual.
- The sensitivity of a test is the ability of the test to correctly identify the diseased. It could also be defined as the proportion of TruePositive (TP)among the diseased [TP/(TP+FN)].
- The specificity of a test is the ability of the test to correctly identify the individual as not diseased. It could also be define as the proportion of TrueNegative (TN)among the not diseased [TN/(TN+FP)].
- DOING CBC for all fevers is not sensitive or specific
- but if you do urine c/s for fever without focus it is justified
- for dx of typhoid ,if you choose widal,it is a poor sensitivity test, modified typhidot is better. a blood or clot culture is specific,gene probe even more specific
- for leukaemia bone marrow and immunophenotyping is specific, cbc has poor sensitivity
- Sensitivity and specificity of a test provides the probability of the test results in the presence or absence of
disease, but a physician is more interested in knowing the probability of disease in the presence of positive or
negative results from the test. That is, if the test is positive for an individual, then what is the probability that the
individual is truly positive? And similarly,
if a test is negative for an individual, then what is the probability that the individual is truly negative?
Superintendent, ICH.