BRISTOL, England—The positive association between a high body mass index (BMI) and all-cause and cardiovascular mortality may be underestimated, while the positive association of a low BMI and respiratory disease and lung cancer mortality may be overstated, according to a new study from the University of Bristol (BMJ. 2009 Dec 22;339:b5043. doi: 10.1136/bmj.b5043).
Researchers used children’s BMI as a predictor of their parents’ BMI to avoid problems of reverse causality in this cohort study with more than one million Swedish parent-son pairs.
They found parental mortality from diabetes, coronary heart disease and kidney cancer had the strongest positive associations with offspring BMI. However, in contrast to the inverse association of own BMI with lung cancer and respiratory disease mortality seen in other studies, there was a positive association between offspring BMI and lung cancer mortality in both mothers and fathers and between offspring BMI and respiratory mortality in both parents.
Associations of own BMI and offspring BMI with all-cause, cardiovascular disease (CVD) related, and non-cardiovascular disease related mortality were compared in a subset of father-son pairs (n=72,815). When offspring BMI was used as a variable for paternal BMI, the causal association between BMI and paternal CVD mortality was stronger than that indicated by the directly observed association between own BMI and CVD mortality.