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@ARTICLE{Gies:147382,
      author       = {A. Gies$^*$ and T. Niedermaier$^*$ and K. Weigl$^*$ and P.
                      Schrotz-King$^*$ and M. Hoffmeister$^*$ and H. Brenner$^*$},
      title        = {{E}ffect of long-term frozen storage and thawing of stool
                      samples on faecal haemoglobin concentration and diagnostic
                      performance of faecal immunochemical tests.},
      journal      = {Clinical chemistry and laboratory medicine},
      volume       = {58},
      number       = {3},
      issn         = {1437-4331},
      address      = {Berlin [u.a.]},
      publisher    = {De Gruyter},
      reportid     = {DKFZ-2019-02499},
      pages        = {390-398},
      year         = {2020},
      note         = {2020 Feb 25;58(3):390-398#EA:C120#LA:C070#},
      abstract     = {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.},
      cin          = {C070 / C120 / HD01},
      ddc          = {610},
      cid          = {I:(DE-He78)C070-20160331 / I:(DE-He78)C120-20160331 /
                      I:(DE-He78)HD01-20160331},
      pnm          = {313 - Cancer risk factors and prevention (POF3-313)},
      pid          = {G:(DE-HGF)POF3-313},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:31655793},
      doi          = {10.1515/cclm-2019-0878},
      url          = {https://inrepo02.dkfz.de/record/147382},
}