Prepared by: Ben Schöttker, German Cancer Research Center, Clinical Epidemiology and Ageing research, Heidelberg, Germany
Contents:
- Summary of GGT assessment in cohorts
- Harmonized GGT variable
- Availability of eligible data in cohorts for the harmonized GGT variable
- Additional comments
- Missing information
- References
1. Summary of GGT assessment in cohorts
Details of collected information about GGT measurement from the CHANCES cohorts are displayed in the attached Excel table.
Four cohorts can provide data (ESTHER, RES, Tromsø and Zutphen). Repeated measurements are available for ESTHER, Tromsø and Zutphen.
Cohorts show the following common ground:
- GGT measurement took place from serum samples stored at -80°C or have been measured immediately (< 48h) from taken blood samples.
- GGT measurement was performed in the total cohort.
Cohorts vary in the following:
- In ESTHER and Zutphen different assays have been applied and in Tromsø and Rotterdam the CHANCES contact person did neither know the apparatus used nor the assay type, yet.
2. Harmonized GGT variable
The following GGT variable has been defined in document Definitions of variables:
3. Availability of eligible data in cohorts for the harmonized GGT variable
- Codable for all four cohorts. Sample size estimation in CHANCES is shown in Table 9.
Table 9 – Number of available GGT measurements in CHANCES cohorts
| Cohort | Contact with data | n | Re-contact with data | n |
|---|---|---|---|---|
| ESTHER | BL | 9,728 | 5-year FUP 8-year FUP |
~ 5,000 ~ 5,000 |
| RES | Latest FU | ? | ||
| Tromsø | 3 | 21,782 | 4 | 27,092 |
| Zutphen | BL | 146 | 5-year FUP 10-year FUP |
? ? |
| Total | ~ 31,656 + RES | ~ 26,000* |
* Only one FUP of ESTHER counted and estimated that 21,000 of participants of Tromsø 3 have repeated measures in Tromsø 4.
3. Additional comments
Currently not enough is known about the applied assay types to judge the comparability of the measurements.
3. Missing information
- All detailed information from RES is missing.
- Serum used in Tromsø 3 and 4?
- GGT analyzed within 48 hours in Tromsö 4 as done in Tromsø 3?
- Have samples been cooled in time gap between blood collection and GGT measurement in Tromsø 3 and 4?
- Assay type in RES, Tromsø and Zutphen?
- Apparatus used in RES and Tromsø?
