Table 2.
Characteristics of the studies included in the systematic review
| Study | Study Design | Patient setting | Patient type | Patient population | Geographic location | Timing of data collection | Source of data | Number of subjects | Time window (months) | Mean Age (years) | Gender | |||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Total | Cases | Control | Male (%) | Female (%) | ||||||||||
| Kinar, 2016 10 | Retrospective cohort+case-control | Primary care | Anyone | Inclusion: Age 50-75. | Israel and UK | Israel: January 2003-June 2011 | Maccabi Healthcare Services (MHS) and the UK Health Improvement Network (THIN) | Israel: 606,403 | Israel: 3,315 | UK: 25,613 | 3-6 | Israel: 58.7 | Israel: 46.4 | Israel: 53.6 |
| Exclusion: Diagnosed with cancers other than CRC. | UK: January 2003-May 2012 | UK: 30,674 | UK: 5,061 | UK: 67.4 | UK: 49.2 | UK: 50.8 | ||||||||
| Kinar, 2017 14 | Retrospective cohort | Primary care | Anyone | Inclusion: Aged 50-75 on January 1, 2008, with≥1 FBC in the MHS during the six-month testing period. | Israel | July 2007-December 2007 | MHS and Israeli Cancer Registry | 112,584 | 133 | 97 | 6 | 60.9 | 44 | 56 |
| Exclusion: Cancer diagnosis before January 1, 2008, or no blood test during the testing period. | ||||||||||||||
| Birks, 2017 16 | Case-control+retrospective cohort | Primary care | Anyone | Inclusion: Patients >40 years old with≥1 FBC in their record. | UK | January 2000-April 2015 | Clinical Practice Research Datalink (CPRD) | 2,550,119 | 25,430 | NA | 18-24 | No CRC=60.5±14.0 | NA | NA |
| Exclusion: <12 months registered, <2 years follow-up, prior CRC or precursors, hemoglobin gene defects. | CRC=72.7±10.5 | |||||||||||||
| Hornbrook, 2017 15 | Retrospective case-control | Unclear | Asymptomatic | Inclusion: Eligible CRC cases with CBC before diagnosis. | United States | 1998-2013 | Kaiser Permanente Northwest | 17,095 | 900 | 16,195 | 0-6 and 6-12 | 58.0±11.8 | 44.1 | 55.9 |
| Region’s Tumor Registry | ||||||||||||||
| Ayling, 2018 21 | Prospective (PGC) and Retrospective cohort (RLH) | Secondary care | Symptomatic | Inclusion: IDA patients referred to Plymouth Gastroenterology Clinic for FIT evaluation; IDA patients referred to Royal London Hospital for colonoscopy. | UK | March 2014-March 2017 | Gastroenterology Clinic in Derriford Hospital, Plymouth, and Royal London Hospital medical records | 592 | NA | NA | NA | Plymouth | 48.14 | 51.86 |
| Male: 70.9 | ||||||||||||||
| Female: 69.1 | ||||||||||||||
| London | ||||||||||||||
| Male: 66 | ||||||||||||||
| Female: 60 | ||||||||||||||
| Exclusion: Patients with non-anemia causes. | ||||||||||||||
| Goshen, 2018 17 | Cohort prospective | Secondary care | Anyone | Inclusion: Ages 50-75 in MHS with CBC recorded between October 2015 and December 2016, without a colonoscopy in the past 10 years, and no FIT in the 18 months before the index CBC. | Israel | October 2015-December 2016 | MHS EMR and Israel Cancer Registry | 79671 | NA | NA | 1-6 and 7-12 | NA | NA | NA |
| Exclusion: Referred for FIT in the last 3 months but not completed, and prior cancer diagnosis. | ||||||||||||||
| Hilsden, 2018 6 | Retrospective cohort and case-control | Secondary care | Asymptomatic | Inclusion: Asymptomatic individuals, 50-75, had a screening colonoscopy from January 2013 to Jun 2015, with a CBC within a year, average CRC risk, and personal/family history of polyps/CRC. | Canada | January 2013-June 2015 | Alberta Health Services Forzani and MacPhail Colon Cancer Screening | 17676 | NA | NA | NA | NA | 46.6 | 53.4 |
| Exclusion: Positive FOBT, prior CRC, genetic predisposition, or no CBC within a year before colonoscopy. | ||||||||||||||
| Schneider, 2020 18 | Retrospective cohort+case-control | Unclear | Anyone | Inclusion: KPNC Health Plan members (1996-2015), aged ≥37, with ≥1 outpatient CBC. Cases: Ages 50-75, CBC, no prior/current CRC diagnosis, later diagnosed with CRC. Controls: Ages 50-75, randomly selected CBC, no CRC diagnosis. Both require a 6-month health plan membership and CBC before colonoscopy. | United States | January 199-December 2015 | Kaiser Permanente Northern California Health Plan | 308,721 | 6,019 | 302,702 | 0-6 and 6-12 | 58.5±7.7 | 48 | 52 |
| Ayling, 2021 22 | Prospective cohort | Secondary care | Symptomatic | Inclusion: Patients over 40, on urgent pathway for suspected CRC on May 1, 2020. | UK | May-October 2020 | Barts Health NHS Trust | 532 | NA | NA | 6 | 63 | 50.81 | 49.82 |
| Exclusion: No final diagnosis, declined investigations, inaccessible, overseas, unable to attend, awaiting definitive investigations, and invalid FIT. | ||||||||||||||
| Holt, 2023 19 | Case-control+retrospective cohort | Primary care | Anyone | Inclusion: Individuals >40 years, with one FBC in CPRD record (01/2000-28/04/2015) and associated ColonFlag score. | UK | January 2000-April 2015 | CPRD and National Cancer Registry | 1,893,641 | 18,130 | 270,750 | 18-24 | NA | NA | NA |
| Exclusion: <2 years follow-up, <12 months registered, or hemoglobin gene defect. | ||||||||||||||