November 30, 2015

Dec. 1st: Biostatistics Journal Club

The Biostatistics Journal Club will meet on Tuesday, December 1st, 2015!

The place is: COPH 2280

The time is: 12:00 – 1:00pm.

Our speaker will be: Reid D. Landes, Ph.D..


Objectives: To investigate effects of low to moderate levels of ionizing radiation on incident atrial fibrillation (AF), while accounting for other risk factors.

Methods: We followed 7379 atomic bomb survivors participating in the Radiation Effects Research Foundation’s Adult Health Study approximately every 2 years from 1967 – 2009. Altogether, participants contributed 176,687 person-years. At the time of the atomic bombings, participants ranged in age from 0 – 67 years old. A quarter of the participants were exposed to between 500 – 3500 mGy, and 39% under 5 mGy. AF diagnoses were based on biennial standard 12-leads electrocardiogram and history taking. We modeled incident AF with Cox’s proportional hazards regression, estimating radiation effects while accounting for other AF risk factors.

Results: Accounting only for sex and city (Hiroshima, Nagasaki), 1 Gy of radiation was not estimated to increase the risk of AF, but rather reduce AF risk by 0.88 (95% CI: 0.69 – 1.10). Adding other risk factors, the estimated AF risk for 1 Gy radiation was still below 1, at 0.85 (95% CI: 0.67 – 1.06). Though some of the risk factors were not evenly distributed across those with no, low, and high radiation exposures, there was no evidence that radiation effects depended on these other risk factors (i.e., no interactions with radiation).

Conclusions: Low to moderate doses (<3.5 Gy) of radiation do not appear to increase the risk of atrial fibrillation.