Assessing the Possible Direct Effect of Birth Weight on Childhood Blood Pressure: A Sensitivity Analysis

作者：Chiolero Arnaud^*; Paradis Gilles; Kaufman Jay S

来源：American Journal of Epidemiology, 2014, 179(1): 4-11.

DOI：10.1093/aje/kwt228

• birth weight
• blood pressure
• collider-stratification bias
• direct effects
• sensitivity analyses

To estimate the possible direct effect of birth weight on blood pressure, it is conventional to condition on the mediator, current weight. Such conditioning can induce bias. Our aim was to assess the potential biasing effect of U, an unmeasured common cause of current weight and blood pressure, on the estimate of the controlled direct effect of birth weight on blood pressure, with the help of sensitivity analyses. We used data from a school-based study conducted in Switzerland in 20052006 (n 3,762; mean age 12.3 years). A small negative association was observed between birth weight and systolic blood pressure (linear regression coefficient (bw) 0.3 mmHg/kg, 95 confidence interval: 0.9, 0.3). The association was strengthened upon adjustment for current weight ((bw|C) 1.5 mmHg/kg, 95 confidence interval: 2.1, 0.9). Sensitivity analyses revealed that the negative conditional association was explained by U only if U was relatively strongly associated with blood pressure and if there was a large difference in the prevalence of U between lowbirth weight and normalbirth weight children. This weakens the hypothesis that the negative relationship between birth weight and blood pressure arises only from collider-stratification bias induced by conditioning on current weight.

• 出版日期2014-1-1