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 Table of Contents  
ORIGINAL ARTICLE
Year : 2019  |  Volume : 31  |  Issue : 3  |  Page : 217-221

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


1 Department of Oral Medicine and Radiology, Maratha Mandal's NGH Institute of Dental Sciences and Research Center, Belgaum, Karnataka, India
2 Department of Oral Medicine and Radiology, K.L.E. V.K. Institute of Dental Sciences, KLE University, Belgaum, Karnataka, India

Date of Submission26-Jul-2018
Date of Acceptance29-Nov-2018
Date of Web Publication30-Sep-2019

Correspondence Address:
Dr. Rohini Praveen Sarnaik
Department of Oral Medicine and Radiology, Maratha Mandal's NGH Institute of Dental Sciences and Research Centre, Belgaum - 590 001, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jiaomr.jiaomr_131_18

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   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.

Keywords: Bone mineral density, cotinine, men, tobacco


How to cite this article:
Sarnaik RP, Bagewadi AS, Keluskar VK. Assessment of correlation between serum cotinine levels and bone mineral density among male tobacco users. J Indian Acad Oral Med Radiol 2019;31:217-21

How to cite this URL:
Sarnaik RP, Bagewadi AS, Keluskar VK. Assessment of correlation between serum cotinine levels and bone mineral density among male tobacco users. J Indian Acad Oral Med Radiol [serial online] 2019 [cited 2019 Dec 14];31:217-21. Available from: http://www.jiaomr.in/text.asp?2019/31/3/217/268274




   Introduction Top


The use of tobacco is one of the greatest threats to universal health today. Approximately one-third of the adult population in the world use tobacco in some form. Amongst them, half die ahead of time. According to World Health Organization (WHO) in World Health Report under Oral Health Programme, Noncommunicable Disease Prevention, and Health Promotion, it is reported that 4.9 million people worldwide died in 2000 as a result of their addiction to nicotine.[1],[2]

Tobacco use causes several chronic diseases. Among these chronic diseases, it also has effects on bones including jaw bones and periodontium.[3],[4]

Tobacco consumption is known to cause decreased bone density, which might result in osteoporosis. Tobacco consumption may affect the bone mineral density (BMD) by its toxicity caused by nicotine and non-nicotine components on the bone cells and indirect effect through decreased intestinal calcium absorption.[5],[6] The physical disability caused by osteoporosis is greater than that of the cancer.[7],[8],[9],[10],[11]

Osteoporosis is a progressive systemic skeletal disease causing reduced bone density. It is characterized by low bone density of bone tissue. Consequently, bone becomes fragile with increased susceptibility to fracture. Osteoporosis can affect any bone in the body, like bones in the hip, spine, wrist, and tooth loss.[12],[13],[14],[15],[16],[17],[18]

The diagnosis of osteoporosis could be done by physical signs and symptoms, X-rays, bone scans, and BMD assessment. Among the several assessment of diagnostic method, ultrasound is an accurate, cost-effective, and easily available approach which has high sensitivity of 99% and specificity of 76%.[19],[20],[21],[22],[23],[24]

The word cotinine is another name of nicotine. Cotinine is used as an indicator or biomarker of exposure to tobacco smoke. It is used as an enhancer and an antipsychotic drug in scientific research. Cotinine is detectable from blood for several days after the use of tobacco. The level of cotinine in blood is proportionate to amount of exposure to tobacco. Therefore, cotinine content in the blood is a clear indicator of exposure to tobacco. Cotinine level assessment provides quantitative measures of exposure to tobacco consumption and is a reliable indicator.[25],[26],[27],[28]

Thus, the present study aimed to assess the effect of tobacco consumption on the BMD among males.


   Materials and Methods Top


Source of data

The study participants were selected from outpatient Department of Oral Medicine and Radiology of KLEVK Institute of Dental Sciences, Belgaum. A total of 120 male subjects in the age group of above 40 years, who consented to be part of study, were included. The study was approved by Ethical and Research Committee of KLE Vishwanath Katti Dental College, Belgaum.

Inclusion criteria

We included the subjects with the habits (smoking, chewing, and smoking with chewing) and divided them into following groups.

  • Group I: Thirty subjects with history of tobacco smoking at least for a period of 1 year
  • Group II: Thirty subjects with history of tobacco chewing at least for a period of 1 year
  • Group III: Thirty subjects with history of both tobacco chewing and smoking at least for a period 1 year
  • Group IV: Thirty subjects with no habits of tobacco consumption either in smoke or smokeless form.


Exclusion criteria

Subject with any systemic diseases such as diabetes, hypertension, and medications that affect bone metabolism like corticosteroids, and calcium supplements; and subject with carcinoma and renal impairment and those who were not willing to participate in the study excluded from the study.

Assessment of bone mineral density

BMD at the wrist region was measured by ultrasound of Sunlight Company from Meyer vitabiotics pharmaceuticals. Subjects were asked to sit comfortably in the chair and place their right-hand wrist on the machine. Subsequently, readings were recorded. Ultrasound uses sound waves to determine BMD in the wrist region [Figure 1].
Figure 1: Estimation of BMD at the wrist region

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BMD is categorized on the basis of t-scores as follows (WHO):[11]

  • Normal: t-score of − 1
  • Osteopenic: t-score of − 1 to − 2.5
  • Osteoporotic: t-score is below − 2.5.


t-Score is the bone density compared with that expected in a normal healthy adult of matched age and sex. The t-score is the number of units of standard deviations (SD) that the bone density is above or below the standard. Essentially, it compares the bone density with the best possible peak bone density.[26]

Assessment of serum cotinine

About 5 ml of venous blood was drawn from the cubital vein after following aseptic procedures. It was transferred to gel-coated tubes and transported to the laboratory. Each sample was then centrifuged for 10 min at 3000 rpm. The supernatant serum obtained was then processed for quantitative estimation of serum cotinine levels automated system.

Commercially available cotinine direct ELISA kit (Calbiotech Company) is intended for the measurement of cotinine in the serum [Figure 2].
Figure 2: Serum cotinine estimation kit

Click here to view


Statistical analysis

Distribution of respondents by age groups was calculated by their mean age. Comparison of three study groups (Group I, Group II, and Group III) was done with mean duration of habit by one-way ANOVA test. Pair-wise comparison of groups was done by Newman–Keuls multiple post-hoc procedures. Comparison of four study groups (Group I, Group II, Group III, and Group IV) with respect to bone density (i.e. t-score) was done by one-way ANOVA test. Comparison of three study groups (Group I, Group II, and Group III) with respect to log serum cotinine levels (in ng/ml) was done by one-way ANOVA test. Correlation between bone density, that is, t-score, and log serum cotinine levels (in ng/ml) was done by Karl Pearson's correlationcoefficient in four study groups (Group I, Group II, Group III, and Group IV). Chi-square test was done to know the association of BMD among the four groups.


   Results Top


The present study comprised 120 male subjects and was divided into 4 groups (Group I consisting of 30 tobacco chewers, Group II consisting of 30 tobacco smokers, Group III consisting of 30 subjects with chewing and smoking habit, and Group IV is a control group of 30 subjects without any habit of tobacco). All the subjects were assessed for BMD and serum cotinine levels. These levels were assessed and correlated between all the four groups. The population included in the study had a mean age of 52.35 ± 8.46 in the entire group. When the duration of habit was seen between groups, there were significant results seen between Group I and Group III, Group I, II, and Group III (P value being P = 0.0003 and 0.0004, respectively. Among all the groups, BMD was lower with chewers group, the mean values being −1.60 with SD of 0.80 when compared to control group (P = 0.0144*), followed by subjects with chewing and smoking habit and smokers group (P = 0.0290*). When cotinine levels were checked between all the groups, levels were high among chewers with mean value of 1278.34 ng/ml with SD of 2014.18 followed by smokers with cotinine value of 648.74 ng/ml (SD 471.29);among chewers and smokers, the value measured 852.79 ng/ml (SD 553.14) and control groups showed 262.92 ng/ml (SD482.29). When three study groups were compared (Group I, Group II, and Group III) with respect to bone density (i.e., t-score) by one-way ANOVA test, it showed there was significant decrease in the mean density of bone among three study groups (P< 0.05) with slight significant decrease in BMD among Group II(−1.60). When the status of BMD in four groups was compared, among smokers group(−1.30) and control group(−1.08), 10 subjects were normal, 19 subjects with osteopenia, and 1 subject with osteoporosis in smokers group. Maximum subjects were osteopenic among subject having both chewing and smoking habit(−1.52). Two subjects were osteoporotic with chewing habit [Table 1].
Table 1: Status of Bone Mineral Density in Four groups

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   Discussion Top


Tobacco is a major public health issue. Its use has been known since the first-century BC. The prevalence of tobacco use is higher among Indian males as compared to females. The use is more among older age groups as compared to the younger age groups. Many organs and body systems are adversely affected by tobacco use. The health risks are highest among heavy users either in smoke or smokeless form.[29]

Smoking and smokeless tobacco lead to mouth cancer, lung cancer, lung diseases, heart disease, premature birth, poor reproductive health in females, and premature death of person. In addition, to these chronic diseases, it also has an effect on bones including jaw bones and periodontium.[30],[31]

Tobacco consumption is known to cause decreased bone density, which might result in osteoporosis. The effect appears to be dose-dependent and it is partially reversible.[2],[4]

Most studies of bone density have been conducted only in women.[31] According Enchev Encho, osteoporosis in men due the use of tobacco has shown deleterious effect in men.[4],[32] Hence, the present study was undertaken to investigate the association between tobacco use and bone mineral density in elderly men.[32],[33],[34],[35]

All the subjects in the present study were in the mean age group of 52.35 ± 8.46. The age range was consistent with the study carried out by Prabhakar et al., that the habits are more prevalent among elderly Indian males when compared to females.[36]

According to study conducted by Jonathan et al., it was seen that there was a dose–response relationship observed between duration of smoking habit and BMD.[37]

In the present study, the mean duration of habit among all the groups is 21.6 years. Among subjects, the duration of smoking was 24.43 years, the duration of chewing was 24.83 years, and duration for both chewing and smoking habit was 15.57 years.

These data are consistent with study carried out by Betul et al., which claimed that BMD was lower among long-term use of smokeless tobacco when compared smokers.[29]

Cotinine is used as an indicator or biomarker of exposure to tobacco use. The level of cotinine in the blood is proportionate to the amount of exposure to tobacco. The harmful effect of tobacco has a long-lasting effect on BMD.

The concentration of cotinine, in different body fluids, is considered to be a better indicator of nicotine intake than self-reported use of tobacco products and thus may be used in quantification of tobacco consumption and nicotine.[37],[38],[39]

In this study, we evaluated the use of serum cotinin levels as a quantitative method to assess the level of tobacco use.

The absorbed dose of nicotine is best indicated by the concentration of cotinine in the blood. The relative stability of cotinine levels in blood over a timeis more when compared to saliva.[37],[40] Levels of cotinine in saliva and blood are highly correlated with saliva-to-blood ratios of 1.1:1.4 (correlation coefficients = 0.82, 0.95).

It was decided to measure cotinine in the serum due to its relative stability.

Our study shows that cotinine levels were stable over a time and high among all the three groups when compared to control with P value being 0.00001* which was significant.

Thus, measuring the serum cotinine can be used as reliable indicator of exposure of tobacco.

According to the epidemiology, smokeless tobacco has shown its potential effect on bone metabolism. Thus, tobacco users should be evaluated thoroughly for effects on BMD and risk for osteoporosis and fracture.[41],[42],[43],[44]

In the present study, BMD was less among all the three groups (P = 0.2011), with indication of osteopenia. Osteopenic subjects were more in the group having both chewing and smoking habit. But the mean density of bone was less among chewers when compared to smokers and subjects who used tobacco in both the form. This indicates that chewing form of tobacco has more ill effects on bones.

Similar results were found in a study conducted by Spangler et al., in which it showed that nicotine or another component from smokeless tobacco had adverse effect on bones.[6],[12]

Among the control group, 10 subjects were osteopenic. The probable cause for the subjects having ostepenia without having tobacco habit could be because of dietary insufficiency of calcium, vitamin D, or passive smoking.

Hence, it is important to identify individuals with low BMD by screening for osteoporosis, particularly among patients with tobacco habit and risk of osteoporosis.

The present study suggests that screening for tobacco exposure by serum cotinine ELISA method and use of densitometer method utilizing WHO t-score criteria is better means of screening. This method is cost-effective and feasible in identifying osteopenia and osteoporosis. Otherwise, it would remain undiagnosed and subsequently develop complications of osteoporosis. The method can be used for wider community surveys to identify the extent of problem.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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