Persistent prevalence of polycythemia among evacuees 4 years after the Great East Japan Earthquake: A follow-up study

We previously reported that the lifestyle of evacuees significantly increased the prevalence of polycythemia compared with non-evacuees at an average of 1.6 years (2011–2012) from the previous annual health checkup before the Great East Japan Earthquake (GEJE). Here we analyzed how the prolonged evacuation affected the prevalence of polycythemia an average of 2.5 years (2013–2014) after the previous data. Subjects were individuals aged 40–90 years living in the vicinity of the Fukushima Daiichi Nuclear Power Plant in Fukushima Prefecture who had attended the annual health checkups since 2008. The prevalence of polycythemia and changes in its defining factors of red blood cell count (RBC), hemoglobin (Hb) level, hematocrit (Ht) level were compared between before and after the GEJE in 7713 individuals (3349 men and 4364 women) receiving follow-up examinations both 2011–2012 and 2013–2014. RBC, Hb levels and Ht levels in 2011–2012 were higher among evacuees than non-evacuees in both men and women. However, all levels in 2013–2014 were on the decline from those in 2011–2012. On the other hand, among evacuees, Hb and Ht levels continued to be higher than before the GEJE in both men and women evacuees. The prevalence of polycythemia, which was diagnosed if one of the defining factors was beyond the standard value, was significantly higher among evacuees than non-evacuees regardless of the presence or the absence of overweight/obesity, smoking, and hypertension. Therefore, prolonged evacuation is a cause of polycythemia even 3 to 4 years after the GEJE and regular health management of evacuees is important.