TABLE 4.

Study 1: Multivariate logistic regression analysis of patient characteristics, physicians and institution setting associated with the use of open-access colonoscopy in Ontario, fiscal year 2006 (n=172,158)

Patients	OR (95% CI)	P
Age, years, median
<50	0.82 (0.78–0.86)	<0.0001
50–69	1.16 (1.06–1.23)	<0.0001
≥70	1 (N/A)	N/A
Sex
Female	1.05 (1.02–1.08)	0.0002
Male	1 (N/A)	N/A
Income quintile
Low	0.78 (0.74–0.82)	<0.0001
2	0.77 (0.74–0.81)	<0.0001
3	0.82 (0.79–0.85)	<0.0001
4	0.87 (0.84–0.90)	<0.0001
High	1 (N/A)	N/A
Comorbidity* (ADGs)
0–3	2.92 (2.81–3.04)	<0.0001
4–5	1.56 (1.50–1.62)	<0.0001
6–7	1.05 (1.00–1.09)	<0.0001
8+	1 (N/A)	N/A
Health region (Ontario)
Erie St Clair	0.44 (0.40–0.48)	<0.0001
South West	1.10 (1.04–1.17)	0.0017
Waterloo Wellington	0.27 (0.25–0.30)	<0.0001
Hamilton Niagara	0.49 (0.46–0.52)	<0.0001
Central West	0.50 (0.47–0.54)	<0.0001
Mississauga Halton	0.99 (0.93–1.05)	0.711
Toronto Central	1.04 (0.99–1.08)	0.1383
Central	0.73 (0.69–0.77)	<0.0001
Central East	0.38 (0.36–0.40)	<0.0001
Champlain	1.70 (1.58–1.82)	<0.0001
North Simcoe Muskoka	1.11 (1.04–1.18)	0.0027
North East	1 (N/A)	N/A
Physician
Specialty
Gastroenterology	1 (N/A)	N/A
Surgery	0.56 (0.54–0.58)	<0.0001
Internal medicine	0.71 (0.67–0.76)	<0.0001
Other practitioner†	1.67 (1.52–1.83)	<0.0001
Physician volume quintile‡
Low	1.05 (1.00–1.09)	0.04
2	0.80 (0.76–0.83)	<0.0001
3	0.78 (0.75–0.82)	<0.0001
4	0.76 (0.73–0.79)	<0.0001
High	1 (N/A)	N/A
Institution
Type
Academic	0.61 (0.58–0.64)	<0.0001
Community	0.15 (0.15–0.16)	<0.0001
Nonhospital	1 (N/A)	N/A

^*Comorbidity scored using number of aggregated diagnosis groups (ADGs) using the Johns Hopkins Case Mix System;

^†Other practitioners comprise all other specialties including family physicians and general practitioners;

^‡Mean annual number of colonoscopies (using the average annual number of colonoscopies performed by the physician in the five years before the colonoscopy). N/A Not applicable