What is the difference between atypical result, out of expectation and out of trend? As we know in biological products , particularly vaccines, regulatory specification is always set like not less than, as for example not less than 2.5 IU/ dose for rabies vaccine and not less than 20mcg for Hepatitis B and measles & rubella vaccine also have same not less than, in that case how we can set atypical, out of expectation and out of trend considering variability of biological product analysis. Could you Pls explain
Hi Mohammad,
Out of specification (OOS): The test results that fall outside the acceptance criteria established
in SOP. (Against Specification limit).
Out of Trend (OOT): The test results that may be within specification but show significant
variation from the historical results.
OOS (out of specification) is the comparison of one result versus predetermined specification
criteria while OOT (Out of Trend) is the comparison of many historical data values versus time.
OOS investigations focus on determining the truth about that one value while OOT
investigations focus on understanding non-random changes
Example:
The specification limit for assay is: 95.0-105.0 % w/w of label claim
Case-1: For a particular batch, the result obtained 94.2 % w/w -This result is out of the
specification limit. This is called OOS.
Case-2: The result obtained 95.8 % w/w. Although the results are well within the
specifications, we should compare the result with the previous batches trend. If we found the
average value of the trend as 99.0 % w/w then this batch result (95.8 % w/w) is called out of
trend.
Out-of-Expectation Results (OOE)
An atypical, aberrant or anomalous result within a series of results obtained over a short period
of time is an OOE result. An OOE result is a result that meets specifications, but is outside the
expected variability of the analytical procedure.