DetectedIssue: date gap status is set to "closed"

With respect to Gaps In Care DetectedIssue.gapStatus, is there anywhere to indicate with the gap was closed. I see DetectedIssue.identified (when identified) but it is unclear as to whether this can be used to identify when the gap is “opened” as well as when it it “closed”.

Not in the core spec. You could propose introducing such an element - or at least a standard extension