Table 1 Networks and practice sites in the Canadian Primary Care Sentinel Surveillance Network (1 July 2007–30 June 2012)

			Total in Network		Total Included in the Study
			#Sites	#Patients^a	#Sites^b	#Patients^a
British Columbia Primary Care Research Network (BCPCReN)	British Columbia	Vancouver, University of British Columbia	1	6541	1	6541
Alberta Family Practice Research Network (AFPRN)	Alberta	Edmonton, University of Alberta	5	16083	1	4602
Southern Alberta Primary Care Research Network (SAPCReN)	Alberta	Calgary, University of Calgary	5	21078	2	16275
Manitoba Primary Care Research Network (MaPCReN)	Manitoba	Winnipeg, University of Manitoba	3	16828	0	0
Deliver Primary Healthcare Information Project (DELPHI)	Ontario	London, Western University	8	14969	8	14966
University of Toronto Practice Based Research Network (UTOPIAN)	Ontario	Toronto, University of Toronto	13	34441	12	33148
Eastern Ontario Network (EON)	Ontario	Kingston, Queen’s University	2	17831	0	0
Maritime Family Practice Research Network (MARNET-FP)	Nova Scotia	Halifax, Dalhousie University	13	27823	0	0
Atlantic Practice Based Research Network (APBRN)	Newfoundland and Labrador	St. John’s, Memorial University of Newfoundland	7	21499	4	11726
Total			57	177093	28	87258

Note. Some practice sites and entire networks without any referral information were excluded.

↵a Patients with 2+ visits within a 12+ month period, and no missing data on age and sex.
↵b Sites were required to have >=90% of their referrals with a description of the type of referral being made were included.