TY  - JOUR
AU  - Gies, Anton
AU  - Niedermaier, Tobias
AU  - Weigl, Korbinian
AU  - Schrotz-King, Petra
AU  - Hoffmeister, Michael
AU  - Brenner, Hermann
TI  - Effect of long-term frozen storage and thawing of stool samples on faecal haemoglobin concentration and diagnostic performance of faecal immunochemical tests.
JO  - Clinical chemistry and laboratory medicine
VL  - 58
IS  - 3
SN  - 1437-4331
CY  - Berlin [u.a.]
PB  - De Gruyter
M1  - DKFZ-2019-02499
SP  - 390-398
PY  - 2020
N1  - 2020 Feb 25;58(3):390-398#EA:C120#LA:C070#
AB  - Background Faecal samples collected and stored frozen over years may be a valuable resource for efficient retrospective evaluation of faecal immunochemical tests (FITs). We aimed to assess how prolonged frozen storage and freeze-thaw cycles might affect measures of faecal haemoglobin (Hb) and diagnostic performance of FITs. Methods From 2005 through 2010, participants of screening colonoscopy (n = 2042) and clinical colorectal cancer (CRC) cases (n = 184) provided faecal samples in stool containers (60 mL). The samples were stored at -80 °C for up to 11 years and underwent three freeze-thaw cycles. Between each cycle, a defined amount of faeces was extracted using the manufacturer's sampling device of one or two FITs (RIDASCREEN, OC-Sensor). Faecal Hb concentration and diagnostic performance were calculated and compared across freeze-thaw cycles. Results For RIDASCREEN and the OC-Sensor, repeat measurements were available for 504 and 551 study participants, respectively. Hb concentrations correlated strongly (0.77 and 0.85, respectively) and diagnostic performance indicators were similar at the repeat measurements among the same FITs. For RIDASCREEN we found even slightly higher Hb levels, sensitivities and area under the curves (AUCs) after the third than after the first freeze-thaw cycle. For the OC-Sensor the Hb levels, sensitivities and AUCs were slightly lower after prolonged storage and one additional freeze-thaw cycle. Conclusions Measures of Hb and diagnostic performance were fairly stable, even after long-term frozen storage and multiple freeze-thaw cycles of raw faecal samples. Faecal samples collected in prospective screening studies and kept frozen at -80 °C before analysis seem useful for timely and efficient retrospective evaluation of FIT performance.
LB  - PUB:(DE-HGF)16
C6  - pmid:31655793
DO  - DOI:10.1515/cclm-2019-0878
UR  - https://inrepo02.dkfz.de/record/147382
ER  -