Exhaled carbon monoxide level and smoking status in urban Khon Kaen adults.
BACKGROUND
Recent data has shown that a great number of Thai adults as well as people worldwide have died from smoking-related diseases. Measurements of exhaled carbon monoxide have been increasingly used to evaluate smoking status and cutoff levels of exhaled carbon monoxide and have been widely reported among other populations but not for the Thai people.


OBJECTIVE
The purpose of the present research was to study the proper cutoff level for exhaled carbon monoxide for detecting smoking status among urban Thai adults residing in Khon Kaen province, Thailand as well as to study the effect of baseline characteristics in modifying the cutoff level of exhaled carbon monoxide.


METHODS
Cross-sectional analytic study.


METHODS
The present study employed existing data whereby the study subjects comprised a total of 420 Thai adults, aged 15-70 years, residing in urban Khon Kaen province, Thailand during the year 2006. The data was obtained through interview and exhaled carbon monoxide measurement. The analyses employed descriptive, bivariate, and multivariable logistic regression.


RESULTS
Findings from the final multivariable logistic regression model revealed good relation between exhaled carbon monoxide levels and tobacco smoking status. Other variables in the model included age-group and the interaction between exhaled carbon monoxide and age-group. Further analysis showed a greater odds ratio in the older age-group, with the odds ratios (95% CI) being 2.50 (1.87, 3.34) and 1.46 (1.31, 1.63) in the older (41-70 years) and younger (15-40 years) age-groups, respectively. In addition, proper cutoff of exhaled carbon monoxide for the older age-group was suggested as 7 ppm, while 8 ppm was more appropriate for the younger age-group. Based on the findings, a baseline characteristic for age modified cutoff level of carbon monoxide was established


CONCLUSIONS
Differences in baseline characteristics should be considered in evaluating smoking status when choosing the cutoff level of exhaled carbon monoxide for any population.
Chatrchaiwiwatana
Supaporn
S
Faculty of Dentistry, Khon Kaen University, Khon Kaen, Thailand.
Ratanasiri
Amornrat
A
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002248:Carbon Monoxide / Q000032:analysis / Q000378:metabolism*; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D005260:Female; D006304:Health Status; D006306:Health Surveys; D006801:Humans; D007407:Interviews as Topic; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D012372:ROC Curve; D012680:Sensitivity and Specificity; D012907:Smoking / Q000009:adverse effects / Q000378:metabolism*; D013785:Thailand; D014505:Urban Population / Q000706:statistics & numerical data*; D055815:Young Adult
D002248:Carbon Monoxide