Vendor reconciliation
How samples are paired, what is compared, visit codes and extra columns.
Central labs, ECG readers, PK labs and imaging vendors send their data in transfers, and every transfer has to be reconciled with what the site entered in the EDC: is every sample there, does it belong to the right subject and visit, do the dates agree. Done by hand this is a VLOOKUP exercise repeated before every transfer and before database lock.
What to upload
- EDC sample log: the listing of the lab, ECG or PK collection form, with subject, visit, collection date and, if collected, time and sample (accession, requisition, kit) ID.
- Vendor transfer: one row per sample or one row per test. Rows with the same sample ID, or the same subject, visit and date, are folded into one sample.
- Last round’s report (optional): the Excel you downloaded last time, with your statuses, owners and comments.
Columns are recognised by name: CDISC names (LBDAT, LBTIM, LBREFID, EGDAT, PCDAT...) and the usual vendor names (Accession Number, Collection Date, Patient ID, Visit Code). Any column can be named by hand under “Matching and columns”. Subject numbers are compared without separators and prefixes: "101-001" and "101001" are the same subject.
How samples are paired
- same sample ID on both sides;
- same subject, visit and collection date;
- same subject and date, different visit;
- same subject and visit, dates within the window (±1 day by default).
Vendors code visits their own way (SCR, D1, W2). Type the correspondence once, as Screening=SCR; Day 1=D1, and keep it with your data transfer agreement.
What is compared
- Subject for samples paired by ID: a sample the vendor holds under another subject is critical, as is one sample ID used for several subjects.
- Visit, collection date and time (time within a tolerance, 30 minutes by default). A date difference beyond the window is critical.
- Extra columns you name, such as fasting status, sex or date of birth:
Fasting = FastingStatus. Y/N, yes/no and да/нет count as the same. - Unpaired samples: in vendor data only (results with no EDC record: critical) and in the EDC only (collected, no results yet, aged from the collection date).
Rounds
The discrepancy sheet of the Excel report has Status, Owner and Comment columns. Upload it next time as “Last round’s report”: your notes follow the same discrepancies, and those that are gone are listed as resolved.
Try it
Example files: edc_lab_samples.csv and central_lab_transfer.csv. Type the visit codes Screening=SCR; Day 1=D1; Week 2=W2 and the extra column Fasting = FastingStatus. You will see a sample the lab holds under another subject, a time and a fasting difference, a visit coded as unscheduled, a sample with no EDC record and one with no results.
Sources
- SCDM, Good Clinical Data Management Practices: chapters on external data transfers and data reconciliation.
- CDISC SDTM: LB, EG and PC domains, where the column names come from.