Table 2.

Acute/subacute hospital-treated somatic disease incidents: crude incidence rate ratios and treatment contact rate ratios of inpatient days and outpatient hospital contacts

	IRR/TCRR (95% CI)	p Value
Before versus during OMT, during OMT as reference (incidence rate=1)
All incidents	1.6 (1.3 to 1.9)	<0.001
Drug-related*	4.2 (2.9 to 6.2)	<0.001
Overdoses	2.8 (1.6 to 5.0)	<0.001
Injecting-related	5.9 (3.1 to 11.4)	<0.001
Other	5.7 (2.8 to 11.9)	<0.001
Non-drug-related	0.7 (0.6 to 1.0)	0.02
Injuries	1.2 (0.9 to 1.5)	0.23
Inpatient days
Drug-related	6.3 (3.4 to 11.8)	<0.001
Non-drug-related	0.5 (0.3 to 1.0)	0.04
Injuries	2.1 (0.7 to 5.7)	0.17
All	1.7 (1.1 to 2.4)	0.01
Outpatient contacts
Drug-related	4.8 (2.7 to 8.3)	<0.001
Non-drug-related	0.7 (0.4 to 1.2)	0.18
Injuries	1.1 (0.7 to 1.6)	0.78
All	1.4 (1.0 to 1.8)	0.04
After versus during OMT, during OMT as reference (incidence rate=1)
All incidents	2.8 (2.1 to 3.9)	<0.001
Drug-related	11.1 (6.6 to 18.5)	<0.001
Overdoses	5.8 (2.7 to 12.3)	<0.001
Injecting-related	12.6 (4.3 to 36.8)	<0.001
Other	16.7 (6.5 to 42.7)	<0.001
Non-drug-related	1.4 (0.9 to 2.2)	0.15
Injuries	0.8 (0.3 to 1.8)	0.57
Inpatient days
Drug-related	25.2 (13.1 to 48.7)	<0.001
Non-drug-related	1.1 (0.5 to 2.3)	0.78
Injuries	4.6 (0.8 to 28.5)	0.98
All	5.9 (3.6 to 9.6)	<0.001
Outpatient contacts
Drug-related	10.6 (4.7 to 25.9)	<0.001
Non-drug-related	1.6 (0.7 to 3.7)	0.26
Injuries	1.1 (0.4 to 3.1)	0.87
All	2.0 (1.1 to 3.8)	0.03

The incidence rate ratios indicate the statistical significance of the changes in incidence rates demonstrated in table 1, estimated by Poisson regression (generalised estimating equations). Patient-years at risk: 1000 before, 813 during and 91 after OMT. Number of incidents: 605 before, 310 during and 106 after OMT.

IRR, incidence rate ratios; OMT, opioid maintenance treatment; TCRR, treatment contact rate ratios.

^*Subgroups in italic.