Table 4.

Association of smoking status, serum cotinine level and the prevalence of osteopenia.

	OR (95% CI)
	Model 1	Model 2	Model 3
Log2-transformed cotinine, ng/mL	1.04 (1.03-1.05)	1.04 (1.03-1.05)	1.04 (1.03-1.05)
Cotinine categories
<0.05 ng/mL	1.00 [Reference]	1.00 [Reference]	1.00 [Reference]
0.05–2.99 ng/mL	0.96 (0.86-1.07)	0.94 (0.84-1.04)	0.95 (0.85-1.06)
≥3 ng/mL	1.65 (1.47-1.85)	1.59 (1.41-1.79)	1.60 (1.42-1.80)
P for trend	<0.001	<0.001	<0.001
Self-reported smoking status, %
Nonsmokers	1.00 [Reference]	1.00 [Reference]	1.00 [Reference]
Former smokers	0.99 (0.90-1.09)	1.01 (0.92-1.12)	1.04 (0.94-1.15)
Current smokers	1.72 (1.52-1.95)	1.69 (1.49-1.93)	1.70 (1.49-1.94)
P for trend	<0.001	<0.001	<0.001

Model 1 was adjusted as age, sex, and race;

Model 2 was adjusted as model 1 plus education level, drinking status, poverty, physical activity, and total energy intake.

Model 3 was adjusted as model 2 plus total cholesterol, high-density lipoprotein cholesterol, serum calcium, history of prednisone or cortisone, hypertension, diabetes, cardiovascular disease, and cancer.