The Use of Electronic Medical Record Data to Analyze the Association Between Atrial Fibrillation and Birth Month

Objectives: The pineal gland completes cell differentiation and growth during infancy, with the secretory capacity for melatonin also determined during this time. Notably, melatonin secretion may be involved in the association between cardiovascular disease risk and birth month. Here, we investigated the association between atrial fibrillation in cardiovascular disease and birth month. This association might present valuable information on the environment during infancy that can reduce future disease risk. Methods: We retrospectively extracted birth date data from 6,016 patients with atrial fibrillation (3,876 males; 2,140 females) from our electronic medical records. The number of live births in Japan fluctuates seasonally. Therefore, we corrected the number of patients for each birth month based on a Japanese population survey report. Then a test of the significance of the association between atrial fibrillation and birth month was performed using a chi-square test. In addition, we compared the results of an analysis of patient data with that of simulated data that showed no association with birth month. Results: The deviations of birth month were not significant (overall: p = 0.631, males: p = 0.842, females: p = 0.333). The number of female patients born in the first quarter of the year was slightly higher than those born in the other quarters of the year ( p = 0.030). However, by comparing the magnitudes of dispersion in the simulated data, it seems that this finding was mere coincidence. Conclusion: An association between atrial fibrillation and birth month could not be confirmed in our Japanese study. This might be due to differences in ethnicity.