Table 2.

Multinomial logistic regression of dual waterpipe and cigarette use compared to exclusive cigarette use and compared to exclusive waterpipe use.

Variable	Dual versus exclusive cigarette use		Dual versus exclusive waterpipe use
	OR (95% CI)	P	OR (95% CI)	P
Age (years)
≤19	Referent		Referent
>19	0.49 (0.37–0.70)	<0.005	1.09 (0.66–1.82)	0.740
Ethnicity / Race
White	Referent		Referent
Black or African American	1.91 (0.96, 3.79)	0.066	0.88 (0.37, 2.09)	0.766
Asian	0.55 (0.29, 1.05)	0.070	0.65 (0.30, 1.44)	0.292
Othera	1.26 (0.74, 2.16)	0.398	0.38 (0.20, 0.72)	0.003
Year
2011	Referent		Referent
2010	1.65 (0.89, 3.06)	0.111	2.57 (1.20, 5.50)	0.015
2009	0.82 (0.43, 1.58)	0.561	2.72 (1.14, 6.49)	0.024
2008	1.33 (0.72, 2.43)	0.360	3.22 (1.48, 7.00)	0.003
2007	1.01 (0.51, 1.97)	0.988	2.63 (1.10, 6.31)	0.030
2006	0.81 (0.45, 1.46)	0.487	2.76 (1.31, 5.81)	0.007
Peers look cool-cigarette
Not cool	Referent		Referent
Cool	0.79 (0.51, 1.22)	0.293	2.81 (1.52, 5.21)	0.001
Very cool	1.16 (0.57, 2.35)	0.682	5.88 (1.21, 28.44)	0.028
Peers look cool-waterpipe
Not cool	Referent		Referent
Cool	1.69 (1.06, 2.71)	0.029	0.82 (0.45, 1.49)	0.516
Very cool	2.77 (1.46, 5.24)	0.002	0.78 (0.35, 1.76)	0.555
Peer influence-cigarette
None	Referent		Referent
Low	0.48 (0.26, 0.88)	0.018	5.46 (2.70, 11.04)	<0.005
Medium	0.48 (0.26, 0.89)	0.020	8.34 (3.98, 17.45)	<0.005
High	0.30 (0.16, 0.57)	<0.005	29.91 (11.70, 76.46)	<0.005
Peer influence-waterpipe
None	Referent		Referent
Low	2.36 (1.21, 4.61)	0.012	0.73 (0.31, 1.73)	0.471
Medium	5.07 (2.57, 9.99)	<0.005	0.52 (0.22, 1.22)	0.131
High	9.18 (4.41, 19.09)	<0.005	0.29 (0.12, 0.72)	0.007
Addiction from social use-waterpipe
None	Referent		Referent
Low	0.81 (0.49, 1.34)	0.413	0.85 (0.41, 1.73)	0.649
Medium	0.85 (0.50, 1.47)	0.569	0.78 (0.36, 1.66)	0.517
High	0.55 (0.30, 1.02)	0.059	0.45 (0.20, 0.97)	0.049

^aHispanic or Latino, American Indian, and Pacific Islander