--BLFL has been removed from SDTMIG v4.0

Rule

VAR-001

Category

Variables removed

Basis

Confirmed Traceable to the published specification text cited below.

Detectability

Define-XML conclusive The Define-XML settles this one way or the other. No further evidence is needed to know whether it applies.

Finding type

Impact

Applies to

SDTMIG 3.2, 3.3, 3.4

What changes in v4.0

Section 4.8, Assumptions for Findings, states in its Baseline Values subsection that "the variable --BLFL has been removed from SDTMIG v4.0". The specification tables agree: --BLFL appears in 25 v3.4 domain tables and in none of the v4.0 ones. --LOBXFL (Last Observation Before Exposure Flag), which the same subsection describes as having been introduced in SDTMIG v3.3 "to address the need for a consistent definition of a value that can serve as a reference with which to compare post-treatment values", appears in 27 v4.0 domains. --LOBXFL is NOT a replacement baseline flag. The same passage states that "the SDTM variable --LOBXFL can be copied to ADaM for traceability and transparency, but only the ADaM variable ABLFL would be used to signify baseline for analysis", and that the two coincide only "when the SAP specifies that the baseline used for analysis is the last non-missing value prior to RFXSTDTC in the DM domain".

What to do about it

Drop --BLFL, and make sure the two questions it was answering are answered separately afterwards. Where the flag marked the last observation before exposure, --LOBXFL carries that forward and the derivation is a timing one, anchored on the exposure reference start. Where it marked a study-specific analysis baseline, --LOBXFL does not carry it: that definition belongs to the SAP and to ADaM's ABLFL, so any analysis dataset or TFL that keyed off --BLFL needs its baseline definition restated and re-validated with the statistician. Establishing which of the two your --BLFL actually was is the first task and the one worth the statistician's time. This rule, VAR-002 and CORE-002 are one baseline-transition workstream: the same decision about which reference start applies, and about what your baseline actually meant, settles all three. Work them together rather than rule by rule.

What the scan can and cannot see

The variable is declared in this Define-XML, and Section 4.8 states the removal in prose rather than leaving it to be inferred from a table.