Date of Defense:
March 1, 2012
Objectives: To examine the relationship between atrial fibrillation (AF) and birth weight (BW) in the Atherosclerosis Risk in Communities (ARIC) cohort and determine if the relationship differs byrace while adjusting for other possible predictors of the association.
Methods: Prospective follow up analysis of incident cases of AF in an ongoing longitudinal cohort study comparing 9016 individuals with different BW groups. We used Cox proportional hazard ratios with 95% confidence intervals to determine the hazard ratios (HR) of AF among the BW groups. We also stratified by gender and race to determine the effects of these covariates.
Results: We found reduction in the risk of AF by increasing BW groups. Compared to individuals in the low BW category, the HR of AF adjusted for cardiovascular risk factors were 0.72(95% confidence interval (CI) 0.54, 0.96) for medium BW and 0.63(95% CI 0.45, 0.89) for the high BW categories (p=0.02). In the white population, the HRs were 0.74 (95% CI 0.53, 1.02) for medium BW, and 0.59 (95% CI 0.40, 0.87) for high BW (p=0.02), compared to those with low BW. The association was not significant in the African American population after adjusting for the cardiovascular risk factors (HR 0.65, 95% CI 0.36, 1.2.0, for medium HR 0.96, 95%CI 0.45, 2.32 for high vs. low BW) (p=0.15). In men, the hazard ratios were medium BW 0.57(95% CI 0.37, 0.88) and high BW 0.51(95% CI 0.33, 0.83) (p=0.02) compared to low BW.
Conclusion: The high and medium BW categories were associated with a lower risk of AF particularly in men and whites in the ARIC cohort. The strength of association was independent of known predictors of AF such as hypertension or diabetes.