Following regulations issued by OHRP 45CFR46.110 and FDA 21CFR56.110, IRBMED commonly uses 'expedited review' procedures for initial and continuing review, and review of proposed changes, for research described by one or more categories on the 1998 list of Expedited Categories published at 63 FR 60364.
Category (5) applies to Research involving materials (data, documents, records, or specimens) that have been collected, or will be collected solely for nonresearch purposes (such as medical treatment or diagnosis).
This can be read to suggest that the category covers only materials generated for non-research purposes, whether retrospective or prospective.
However, OHRP issued in 2007 a clarification of the scope of Expedited Category (5) at 72 FR 60849: OHRP has concluded that expedited review category 5 was intended to, and should, include ... research involving existing information or specimens that were previously collected for research purposes---provided they were not collected for the currently proposed research.