Table 5.

Example of How a Sequence of Specified Category Misclassifications of Body Mass Index Changed the Direction of the Mortality Hazard Ratio^a for Overweight in the Restricted Sample^b of Men, Using Data From National Health and Nutrition Examination Survey II (1976–1980), III (1988–1994), and Continuous (1999–2010), United States

Number of BMI Misclassifications	Referentc to Low	Referent to Overweight	Overweight to Referent	Class I Obese to Overweight	HR for Overweight
None	No	No	No	No	0.85
1	No	Yes	No	No	0.97
2	No	Yes	Yes	No	1.08
3	No	Yes	Yes	Yes	1.17
4	Yes	Yes	Yes	Yes	1.24

Abbreviations: BMI, body mass index; HR; hazard ratio.

^a Hazard ratios from Cox proportional hazards models, with age as the timeline and adjusted for survey, smoking status, racial/ethnic group, and alcohol consumption. The reference category was BMI of 22.5–24.9.

^b The restricted sample was limited to participants who reported never smoking, who reported no history of heart disease or cancer, and who were examined when younger than age 70 years.

^c BMI was calculated as weight (kg)/height(m)². BMI classifications were as follows: <22.5 (low), 22.5–24.9 (reference), 25.0–29.9 (overweight), 30.0–34.9 (class I obesity), and ≥35.0 (class II–III obesity).