Assessment of correlation between serum cotinine levels and bone mineral density among male tobacco users

Abstract

Osteoporosis is a progressive systemic skeletal disease causing reduced bone density. It is characterized by low density of bone tissue. Consequently, a bone becomes fragile with increased susceptibility to fracture. Tobacco exposure has been implicated as a risk factor for decreased bone density, which might result in osteoporosis. The early identification of individuals with low bone mineral density (BMD) and clinical risk factors, accurate diagnosis of osteoporosis and osteopenia, and initiation of appropriate treatment are crucial to reducing the incidence of fractures. Cotinine, a metabolite of nicotine, is commonly used as a marker for tobacco exposure. Objectives: The objective of the present study was to measure the serum cotinine levels and correlate these findings with BMD among male tobacco users either in smoke or smokeless form. Materials and Methods: A total of 120 subjects were included in the study and divided into 4 groups. Group I comprised 30 subjects with a history of tobacco chewing at least for a period of 1 year. Group II comprised 30 subjects with a history of tobacco smoking at least for a period of 1 year.Group III comprised 30 subjects with a history of both tobacco chewing and smoking at least for a period of 1 year. Group IV comprised 30 subjects with no habits of tobacco consumption either in smoke or smokeless form. Serum cotinine levels were assessed among all the four groups (Group I, Group II, Group III, and Group IV) using commercially available cotinine ELISA kit. The BMD was measured among all four groups by bone densitometry using ultrasound. Statistical analysis was done by one-way ANOVA test for comparison of BMD among study groups.Correlation was assessed between bone density, that is, t-score, and serum cotinine levels (in ng/ml) by Karl Pearson's correlation coefficient in four study groups. Chi-square test was done to know the association of BMD among the four groups. Results: The study result revealed that BMD was less among all the three groups when compared to control group (P = 0.2011), with indication of osteopenia. The mean density of bone was less among chewers (Group II) when compared to smokers (Group I) and subjects who used tobacco in both the form (Group III); also, the osteopenic subjects were more in the group who used tobacco in both form. The serum cotinine levels were significantly high among all the three groups when compared to control group (P = 0.00001). Conclusion: Thus, the present study affirms that use of tobacco affects the bone density among male tobacco users. This effect is more among those who use tobacco in smokeless form.