Misclassification probability as obese or lean in hypercaloric and normocaloric diet

The aim of the present study was to determine the classification error probabilities, as lean or obese, inhypercaloric diet-induced obesity, which depends on the variable used to characterize animal obesity. Inaddition, the misclassification probabilities in animals submitted to normocaloric diet were also evaluated.Male Wistar rats were randomly distributed into two groups: normal diet (ND; n=31; 3,5 Kcal/g) and hypercaloric diet (HD; n=31; 4,6 Kcal/g). The ND group received commercial Labina rat feed and HDanimals a cycle of five hypercaloric diets for a 14-week period. The variables analysed were body weight, body composition, body weight to length ratio, Lee index, body mass index and misclassification probability. A 5% significance level was used. The hypercaloric pellet-diet cycle promoted increase of body weight, carcass fat, body weight to length ratio and Lee index. The total misclassification probabilities ranged from 19.21% to 40.91%. In conclusion, the results of this experiment show that misclassification probabilities occur when dietary manipulation is used to promote obesity in animals. This misjudgement ranges from 19.49% to 40.52% in hypercaloric diet and 18.94% to 41.30% in normocaloric diet.

Relation between cotinine in the urine and indices based on self-declared smoking habits

<p><b>OBJECTIVES</b>The reliability of surveys on smoking habits based on questionnaires was investigated, using the urinary cotinine content as an objective index.</p><p><b>METHODS</b>The subjects tested were 2,849 office workers of middle age, who responded to questions concerning their smoking status, and also their urinary cotinine was measured by the HPLC method.</p><p><b>RESULTS</b>The boundary value between smokers and non-smokers, determined by the histogram independent of the questionnaire, was 63.1 and 79.4 ng/mg of creatinine for males and females, respectively. The rate of misclassification of the non-smokers and former smokers as smokers was 1.3% for males and 1.8% for females, whereas that of current smokers as non-smokers was 6.3% and 2.1%. We also assessed the effect of smoke inhalation on the urinary cotinine value, and found a significant difference for males in the cotinine value by the presence of inhalation and also its depth.</p><p><b>CONCLUSIONS</b>The rate of misclassification in this study was considered to be comparatively low. Several studies have also assessed the reliability of the questionnaire on smoking habits, and found different misclassification rates, indicating the dependence on the race and number of subjects tested. To our knowledge, there were only a few surveys on smoking among large groups, particularly in Japan, such as this one, therefore the results obtained in this study are meaningful.</p>

Relation between Cotinine in the Urine and Indices Based on Self-Declared Smoking Habits

Objectives: The reliability of surveys on smoking habits based on questionnaires was investigated, using the urinary cotinine content as an objective index. Methods: The subjects tested were 2,849 office workers of middle age, who responded to questions concerning their smoking status, and also their urinary cotinine was measured by the HPLC method. Results: The boundary value between smokers and non-smokers, determined by the histogram independent of the questionnaire, was 63.1 and 79.4 ng/mg of creatinine for males and females, respectively. The rate of misclassification of the non-smokers and former smokers as smokers was 1.3% for males and 1.8% for females, whereas that of current smokers as non-smokers was 6.3% and 2.1%. We also assessed the effect of smoke inhalation on the urinary cotinine value, and found a significant difference for males in the cotinine value by the presence of inhalation and also its depth. Conclusions: The rate of misclassification in this study was considered to be comparatively low. Several studies have also assessed the reliability of the questionnaire on smoking habits, and found different misclassification rates, indicating the dependence on the race and number of subjects tested. To our knowledge, there were only a few surveys on smoking among large groups, particularly in Japan, such as this one, therefore the results obtained in this study are meaningful.