A test of recently proposed BMI standards with respect to old age

The purpose of this study was to investigate the effects of age on the relationship between BMI and multiple coronary risk factors, and to determine whether the BMI classification by NHLBI and WHO is applicable as a predictor of coronary risk factors in older (>65 years) as well as in younger (<65 years) men and women. Effects of age on ten coronary risk factors were examined. Sex differences in the slopes of BMI on risk factors were compared between younger and older subjects in order to examine the effects of age on these relationships. The frequency of risk factor abnormality in individual BMI groups (18.5-24.9, 25.0-29.9, 30.0+) was examined for four age-sex groups. The significance of an age group-BMI interaction term was tested by the logistic regression model to see whether there is a significant difference in the relationship between BMI and the individual risk factor abnormalities between younger and older subjects. Older subjects had significantly higher values for most risk factors than younger subjects. The slopes of BMI on risk factors were different between younger and older subjects for fasting glucose, total, HDL- and LDL-cholesterol in men, and for diastolic blood pressure, total and LDL-cholesterol in women. The proportion of subjects with abnormal risk factor levels in each of the three BMI groups was higher in older than in younger subjects for most risk factors. There was generally a progressive worsening of the risk factor levels with increasing BMI in both age groups. There was no consistent age difference in the relationship between BMI groups and the frequency of risk factor abnormality. We conclude that, although age increases the frequency of most cardiovascular risk factor abnormalities, in general, it does not affect the trend of the relationship between the risk factors and the normal, overweight and obese BMI groups defined by NHLBI and WHO. Therefore, these BMI categories are applicable as predictors of risk factor levels in older as well as in younger men and women.