Table 1. Study characteristics of seven colorectal cancer cohort data sets.

Cohort name	CRUX	CAPER	CRCDK	ALBERTA	CAP	DECCIRE	NACDPC
Project	Comparing rural and urban cancer care	Cancer prediction in Exeter	Colorectal cancer in Denmark	Not named	Cancer in primary care	Delay cancer colon i recto	National audit of cancer diagnosis in primary care
Reference	Robertson et al, 2004; Murchie et al, 2014	Hamilton et al, 2005; Stapley et al, 2006	Korsgaard et al, 2006a, 2006b; Iversen et al, 2009	Unpublished	Jensen et al, 2014a, 2014b	Esteva et al, 2007, 2013	Rubin et al, 2011; Lyratzopoulos et al, 2013
Population	Scotland	England	Denmark	Canada	Denmark	Spain	England
Region/county	Highland and Grampian regions	Devon county	Aarhus, Ringkoebing and Ribe counties	Province of Alberta	Aarhus County (CAP1) Central and Southern DK (CAP2) All of Denmark (CAP3)	Baleares, Galicia, Valencia, Catalunya and Aragón regions	1170 volunteering practices from 20 Cancer Networks representing 14% of all practices in England
Study period	Jan 1997–Dec 1998	Jan 1998–Dec 2002	Jan 2001–July 2002	Jan 2004–Dec 2008	Sept 2004–Aug 2005 (CAP1) Oct 2007–Sept 2008 (CAP2) May 2010–Aug 2010 (CAP3)	Sept 2006–Sept 2008	April 2009–April 2010
Study design	Registry-based	Registry-based	Patient-based	Registry-based	PCP-based	Patient-based	PCP-based
Identification	Scottish Cancer Registry	Exeter Cancer Registry	Hospital departments	Provincial Cancer Registry	Hospital Discharge Registry	Hospital departments	English Cancer Networks
Disease classification	ICD-10 C18, C19 and C20	ICD-O-3 8140, 8480, 8490, 8020	ICD-10 C18, C19 and C20	ICD-10 C18, C19 and C20	ICD-10 C18, C19 and C20	ICD-9 153–154	ICD-10 C18, C19 and C20
Validation	Histological confirmation	Histological confirmation	Histological confirmation (Pathology reports)	Histological confirmation	Histological confirmation (Danish Cancer Registry)	Histological confirmation (pathology reports)	Practice records including hospital correspondence
Data sources	Primary care records and governmental hospital admissions data	Electronic primary care record	Interviewer-administered patient questionnaires	Physician billings and hospital records	PCP-questionnaires requesting dates from electronic patient files and hospital discharge letters	Patient interviews combined with review of primary care and hospital records	PCP-audit tool requesting dates from practice records and hospital correspondence
Definitions	Algorithm	Case-Control review	Interview	Algorithm	Questionnaire	Interview and review	Audit
Date of presentation	Earliest recorded colorectal cancer symptom in the year before diagnosis	Earliest recorded colorectal cancer symptom in the year before date of diagnosis	‘When did you first present the above stated symptoms to a doctor?’	The earlier of: first recorded CRC symptom or PCP visit prior to first CRC procedure in the year before diagnosis	‘When did the patient first present to your practice with symptoms which you think are related to the current cancer diagnosis?’	Researchers browsed primary care records	First notification to any health-care professional working within the Primary Health-Care Team about a probable symptom or sign of cancer
Date of referral	Date of first PCP referral or date of emergency admission to hospital	Not collected	‘When were you referred to hospital for further investigation?’	Date of first PCP visit prior to colonoscopy or other CRC-related procedure	‘At which date did you/your practice decide to refer the patient for further investigation?’	Researchers browsed primary care records, but not in the Aragón region (n=214)	Referral to secondary care for further investigation or management of probable symptom or sign of cancer
Date of diagnosis	Scottish Cancer Registry incidence date	Date of positive histology or date given by the specialist	‘What decisive examination led to your current hospitalisation?’	Date in cancer registry which is almost always the date of first positive histology	Danish Cancer Registry incidence date	Date of positive histology (date of the first pathology report)	Not collected
Tumour stage	Dukes	Dukes	Dukes and TNM	TNM	TNM	TNM	SEER 2–4
Symptom data	17 CRC symptoms (ICPC)	11 CRC symptoms (ICPC)	17 CRC symptoms (patients’ first symptom experience)	12 CRC symptoms	11–22 cancer symptoms presented in primary care	9 CRC symptoms (patients’ first symptom experience)	11 CRC symptoms (ICPC)
Emergency admission	Type of first hospital visit=A&E and emergency admission according to hospital admission data	Surgical admission for suspected bowel obstruction or perforation with CRC diagnosed during admission	‘How were you admitted to the surgical department’ response: acute or sub-acute admission	Emergency admission with CRC-related issue within 7 days prior to diagnosis	Acute or sub-acute admission according to National Patient Registry NB: Not collected for the second and third subcohort (n=1569)	Route to diagnosis=emergency department according to hospital record	Type of referral=emergency according to primary care record (audit tool)

Abbreviations: CRC=colorectal cancer; ICD-10=International Classification of Diseases 10th revision; ICD-9 International Classification of Diseases 9th revision; ICD-O-3=WHO International Classification of Disease for Oncology; ICPC=International Classification of Primary Care; PCP=primary care physician; SEER=Surveillance, Epidemiology and End Results (cancer reporting standard of the National Cancer Institute); TNM=Tumour, node, metastasis.

Study characteristics of seven colorectal cancer cohort data set.