Table 3.

Associations between study variables and the incidence of severe complications of tramadol overdose based on a backward logistic regression model¹

Variable	OR (95% CI)	p-value
GCS score
<9	3.80 (2.00, 4.00)	<0.001
9-15	2.00 (0.15, 2.45)	0.024
>15	1.00 (reference)
Tramadol dose (mg)
>2,000	3.55 (2.37, 4.73)	<0.001
1,000-2,000	1.34 (0.02, 2.66)	0.039
<1,000	1.00 (reference)	-
In the process of quitting drug use
Yes	2.99 (1.22, 3.75)	<0.001
No	1.00 (reference)
Age (yr)
30-39	2.23 (1.26, 3.38)	0.013
40-49	3.23 (1.17, 4.28)	<0.001
≥65	1.00 (reference)
Sex
Male	4.21 (2.09, 5.48)	<0.001
Female	1.00 (reference)

GCS, Glasgow Coma Scale; OR, odds ratio; CI, confidence interval.

¹Logistic regression showed acceptable model fit (χ²(4)=4.463, p=0.043).