FDA announces revisions to the 2006 guidance “Investigating Out-of-Specification (OOS) Test Results for Pharmaceutical Production.” Specifically, this revision updates terminology for consistency with current FDA guidance, e.g., quality control unit is changed to quality unit, as well as clarifies concepts related to addressing outlier results, and practices related to the averaging of OOS results.

This guidance provides FDA’s current thinking on how to evaluate OOS test results. For purposes of this guidance document, the term OOS results includes all test results that fall outside the specifications or acceptance criteria established in drug applications, drug master files, official compendia, or by the manufacturer. The term also applies to all in-process laboratory tests that are outside of established specifications. [FDA]