What's the retention period required for the documents of the quality assurance and improvement program (QAIP), specifically for the processes of ongoing reviews and periodic assessments both internal and external?

There is not a required retention period for the QAIP. However, a guide would be to follow the five-year external quality assessment (QA) timeline, i.e., drop off the oldest year's set of documents every five years. Caution: As a general rule, the IA Function should follow their organization's record retention policies when determining how long documents should be maintained.